Probing Molecular Electronic Structure Using High Harmonic Generation TomographyChelsey Crosse
The structure of valence electronic orbitals of a molecule determines the majority of chemical properties. Generation of high-order harmonic frequencies from atomic sources has been directly related to the electronic structure of the atom, (1) and extended as far as tomographic reconstruction of linearly symmetric polyatomic molecular systems with some success. (2,3,4)
However, because of the increased resolution of these reconstructions, discrimination of fine details of the orbital reconstructions reveals some inconsistencies in the orbital shapes when compared with past models & theoretical calculations. (2) There are several proposed corrections to the Strong Field Approximation (SFA) that currently underlies tomographic reconstruction as well as all other experiments that use high harmonic generation (HHG) to probe molecular systems. (5,6,7)
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1. Lewenstein et al. Phys Rev A 49 (3) 1994.
2. Salieres, Maquet, Haessler, Caillat, Taieb. Rep. Prog. Phys. 75 (2012) 062401.
3. Li, Liu, Yang, Song, Zhao, Lu, Li, Xu. Opt. Ex. 21 (6) 2013. 7599.
4. Torres et al. Phys Rev. Lett. 98 (2007) 203007.
5. Diveki et. al. J. Chem Phys. 414 (2013) 121.
6. Yip, Palacios, Rescigno, McCurdy, Martin. J. Chem Phys 414 (2013) 112.
7. Spanner, Patchkovskii. J. Chem. Phys. 414 (2013) 10.
Plenary lecture of the XIII SBPMat (Brazilian MRS) meeting, given on September 30th 2014 by Karl Leo, professor of optoelectronics at Dresden University of Technology (Germany) and director of the Solar and Photovoltaic Engineering Research Center at KAUST (Saudi Arabia).
Plenary lecture of the XIII SBPMat (Brazilian MRS) meeting, given on September 30th, 2014, in João Pessoa (Brazil) by Sir Colin Humphreys, Professor at University of Cambridge (U.K.).
Flexible and Ultrasoft Inorganic 1D Semiconductor and Heterostructure Systems...Pawan Kumar
Low dimensionality and high flexibility are key demands for flexible electronic semiconductor devices. SnIP, the first atomic-scale double helical semiconductor combines structural anisotropy and robustness with exceptional electronic properties. The benefit of the double helix, combined with a diverse structure on the nanoscale, ranging from strong covalent bonding to weak van der Waals interactions, and the large structure and property anisotropy offer substantial potential for applications in energy conversion and water splitting. It represents the next logical step in downscaling the inorganic semiconductors from classical 3D systems, via 2D semiconductors like MXenes or transition metal dichalcogenides, to the first downsizeable, polymer-like atomic-scale 1D semiconductor SnIP. SnIP shows intriguing mechanical properties featuring a bulk modulus three times lower than any IV, III-V, or II-VI semiconductor. In situ bending tests substantiate that pure SnIP fibers can be bent without an effect on their bonding properties. Organic and inorganic hybrids are prepared illustrating that SnIP is a candidate to fabricate flexible 1D composites for energy conversion and water splitting applications. SnIP@C3N4 hybrid forms an unusual soft material core–shell topology with graphenic carbon nitride wrapping around SnIP. A 1D van der Waals heterostructure is formed capable of performing effective water splitting.
Probing Molecular Electronic Structure Using High Harmonic Generation TomographyChelsey Crosse
The structure of valence electronic orbitals of a molecule determines the majority of chemical properties. Generation of high-order harmonic frequencies from atomic sources has been directly related to the electronic structure of the atom, (1) and extended as far as tomographic reconstruction of linearly symmetric polyatomic molecular systems with some success. (2,3,4)
However, because of the increased resolution of these reconstructions, discrimination of fine details of the orbital reconstructions reveals some inconsistencies in the orbital shapes when compared with past models & theoretical calculations. (2) There are several proposed corrections to the Strong Field Approximation (SFA) that currently underlies tomographic reconstruction as well as all other experiments that use high harmonic generation (HHG) to probe molecular systems. (5,6,7)
---------------------------------------------------------------------
1. Lewenstein et al. Phys Rev A 49 (3) 1994.
2. Salieres, Maquet, Haessler, Caillat, Taieb. Rep. Prog. Phys. 75 (2012) 062401.
3. Li, Liu, Yang, Song, Zhao, Lu, Li, Xu. Opt. Ex. 21 (6) 2013. 7599.
4. Torres et al. Phys Rev. Lett. 98 (2007) 203007.
5. Diveki et. al. J. Chem Phys. 414 (2013) 121.
6. Yip, Palacios, Rescigno, McCurdy, Martin. J. Chem Phys 414 (2013) 112.
7. Spanner, Patchkovskii. J. Chem. Phys. 414 (2013) 10.
Plenary lecture of the XIII SBPMat (Brazilian MRS) meeting, given on September 30th 2014 by Karl Leo, professor of optoelectronics at Dresden University of Technology (Germany) and director of the Solar and Photovoltaic Engineering Research Center at KAUST (Saudi Arabia).
Plenary lecture of the XIII SBPMat (Brazilian MRS) meeting, given on September 30th, 2014, in João Pessoa (Brazil) by Sir Colin Humphreys, Professor at University of Cambridge (U.K.).
Flexible and Ultrasoft Inorganic 1D Semiconductor and Heterostructure Systems...Pawan Kumar
Low dimensionality and high flexibility are key demands for flexible electronic semiconductor devices. SnIP, the first atomic-scale double helical semiconductor combines structural anisotropy and robustness with exceptional electronic properties. The benefit of the double helix, combined with a diverse structure on the nanoscale, ranging from strong covalent bonding to weak van der Waals interactions, and the large structure and property anisotropy offer substantial potential for applications in energy conversion and water splitting. It represents the next logical step in downscaling the inorganic semiconductors from classical 3D systems, via 2D semiconductors like MXenes or transition metal dichalcogenides, to the first downsizeable, polymer-like atomic-scale 1D semiconductor SnIP. SnIP shows intriguing mechanical properties featuring a bulk modulus three times lower than any IV, III-V, or II-VI semiconductor. In situ bending tests substantiate that pure SnIP fibers can be bent without an effect on their bonding properties. Organic and inorganic hybrids are prepared illustrating that SnIP is a candidate to fabricate flexible 1D composites for energy conversion and water splitting applications. SnIP@C3N4 hybrid forms an unusual soft material core–shell topology with graphenic carbon nitride wrapping around SnIP. A 1D van der Waals heterostructure is formed capable of performing effective water splitting.
Harvesting Hot Holes in Plasmon-Coupled Ultrathin Photoanodes for High-Perfor...Pawan Kumar
The harvesting of hot carriers produced by plasmon decay to generate electricity or drive a chemical reaction enables the reduction of the thermalization losses associated with supra-band gap photons in semiconductor photoelectrochemical (PEC) cells. Through the broadband harvesting of light, hot-carrier PEC devices also produce a sensitizing effect in heterojunctions with wide-band gap metal oxide semiconductors possessing good photostability and catalytic activity but poor absorption of visible wavelength photons. There are several reports of hot electrons in Au injected over the Schottky barrier into crystalline TiO2 and subsequently utilized to drive a chemical reaction but very few reports of hot hole harvesting. In this work, we demonstrate the efficient harvesting of hot holes in Au nanoparticles (Au NPs) covered with a thin layer of amorphous TiO2 (a-TiO2). Under AM1.5G 1 sun illumination, photoanodes consisting of a single layer of ∼50 nm diameter Au NPs coated with a 10 nm shell of a-TiO2 (Au@a-TiO2) generated 2.5 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias, rising to 3.7 mA cm–2 in the presence of a hole scavenger (methanol). The quantum yield for hot-carrier-mediated photocurrent generation was estimated to be close to unity for high-energy photons (λ < 420 nm). Au@a-TiO2 photoelectrodes produced a small positive photocurrent of 0.1 mA cm–2 even at a bias of −0.6 V indicating extraction of hot holes even at a strong negative bias. These results together with density functional theory modeling and scanning Kelvin probe force microscope data indicate fast injection of hot holes from Au NPs into a-TiO2 and light harvesting performed near-exclusively by Au NPs. For comparison, Au NPs coated with a 10 nm shell of Al2O3 (Au@Al2O3) generated 0.02 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias. These results underscore the critical role played by a-TiO2 in the extraction of holes in Au@a-TiO2 photoanodes, which is not replicated by an ordinary dielectric shell. It is also demonstrated here that an ultrathin photoanode (<100 nm in maximum thickness) can efficiently drive sunlight-driven water splitting.
Noble Metal Free, Visible Light Driven Photocatalysis Using TiO2 Nanotube Arr...Pawan Kumar
Bulk g-C3N4 is an earth-abundant, easily synthesizable, and exceptionally stable photocatalyst with an electronic bandgap of 2.7 eV. Herein, the concepts of P-doping and size quantization are combined to synthesize highly fluorescent P-doped carbon nitride quantum dots (CNPQDs) with a bandgap of 2.1 eV. CNPQDs are hosted on anatase-phase and rutile-phase TiO2 nanotube array scaffolds, and examined as photoanodes for sunlight-driven water-splitting and as photocatalysts for surface catalytic reactions. Square-shaped rutile phase TiO2 nanotube arrays (STNAs) decorated with CNPQDs (CNPQD-STNA) generate 2.54 mA cm−2 photocurrent under AM1.5 G simulated sunlight. A champion hydrogen evolution rate of 22 µmol h−1 corresponds to a Faradaic efficiency of 93.2%. In conjunction with Ag nanoparticles (NPs), the CNPQD-STNA hybrid is also found to be an excellent plexcitonic photocatalyst for the visible light-driven transformation of 4-nitrobenzenethiol (4-NBT) to dimercaptoazobenzene (DMAB), producing reaction completion at a laser power of 1 mW (532 nm) while Ag NP/TNA and Ag NP/STNA photocatalysts cannot complete this transformation even at 10 mW laser power. The results point the way forward for photochemically robust, noble metal free, visible light harvesting photoacatalysts based on nanostructured heterojunctions of graphenic frameworks with TiO2.
Photovoltaics: Fundamental Concepts and novel systems
Energy levels -bands
Doping of semiconductors
Energy band alignments between different phases
Space charge layers
p-n junctions, Schottky barriers
p-n cells, Si cells, thin film cells
Schottky cells (solid and liquid junction)
p-i-n cells
Fundamental limits of photovoltaic cells
How to overcome/ bypass these limits
New generation cells (brief survey)
PV stability, efficiencies and economics
https://www.linkedin.com/in/preeti-choudhary-266414182/
https://www.instagram.com/chaudharypreeti1997/
https://www.facebook.com/profile.php?id=100013419194533
https://twitter.com/preetic27018281
Please like, share, comment and follow.
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If any query then contact:
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Thanking-You
Preeti Choudhary
The Effects of Nitrogen and Oxygen Atmosphere on the Photoconductivity of Tri...journalBEEI
Organic materials were previously used as insulators in electrical technology. These materials, however, are currently used as conductors once their photoconductivity is confirmed and studied. From the literature, it has shown that the photoconductivity of trimethyl phenyl diamine (TPD) increases in the air and decreased in the atmosphere of the vacuum. To the best of our knowledge, there is no detailed study of the effects of gas in the air that affect TPD photoconductivity. In this study we investigate the effects of nitrogen (N2) and oxygen (O2) gases on photoconductivity, degradation and residual decay of photoconductivity for thin film TPD. The results of the study show that in the atmosphere of O2, TPD produces about seven times higher photoconductivity compared to N2 conditions. It also shows that, N2 and O2 provide more effective response time during photoconductivity residual decay. Photoconductivity degradation occurs in all conditions and its recovery takes more than 65 hours.
Plenary lecture given by Prof. Hajo Freund (Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany) on September 11, 2017 in Gramado (Brazil) during the XVI B-MRS Meeting.
Efficient charge transfer induced organic/inorganic based hybrid heterojunction of Ppy/GaN nanorods for high-performance self-powered UV photodetection
Study of Measurement of luminescence life time of the Nd3+ ions in the 6-FDA/...IJERA Editor
Luminescence life time measurements of the Nd3+ ions in the 6-FDA/UVR and Al2o3 hosts were performed
using a Laser diode emitting at 800nm as the excitation source. Optical losses in both materials have been
studied and compared absorption bands of Nd3+ have been observed at 580nm ,745nm, 800nm and 870nm .
Based on which Judd- ofelt analysis has been applied to study the transition properties of Nd3+ ions in the two
hosts. Photoluminescence spectra of Nd3+ have been experimentally studied and emission around 880nm,
1060nm and 1330nm is observed, which indicates that Nd3+ ions are active in these two hosts.
Harvesting Hot Holes in Plasmon-Coupled Ultrathin Photoanodes for High-Perfor...Pawan Kumar
The harvesting of hot carriers produced by plasmon decay to generate electricity or drive a chemical reaction enables the reduction of the thermalization losses associated with supra-band gap photons in semiconductor photoelectrochemical (PEC) cells. Through the broadband harvesting of light, hot-carrier PEC devices also produce a sensitizing effect in heterojunctions with wide-band gap metal oxide semiconductors possessing good photostability and catalytic activity but poor absorption of visible wavelength photons. There are several reports of hot electrons in Au injected over the Schottky barrier into crystalline TiO2 and subsequently utilized to drive a chemical reaction but very few reports of hot hole harvesting. In this work, we demonstrate the efficient harvesting of hot holes in Au nanoparticles (Au NPs) covered with a thin layer of amorphous TiO2 (a-TiO2). Under AM1.5G 1 sun illumination, photoanodes consisting of a single layer of ∼50 nm diameter Au NPs coated with a 10 nm shell of a-TiO2 (Au@a-TiO2) generated 2.5 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias, rising to 3.7 mA cm–2 in the presence of a hole scavenger (methanol). The quantum yield for hot-carrier-mediated photocurrent generation was estimated to be close to unity for high-energy photons (λ < 420 nm). Au@a-TiO2 photoelectrodes produced a small positive photocurrent of 0.1 mA cm–2 even at a bias of −0.6 V indicating extraction of hot holes even at a strong negative bias. These results together with density functional theory modeling and scanning Kelvin probe force microscope data indicate fast injection of hot holes from Au NPs into a-TiO2 and light harvesting performed near-exclusively by Au NPs. For comparison, Au NPs coated with a 10 nm shell of Al2O3 (Au@Al2O3) generated 0.02 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias. These results underscore the critical role played by a-TiO2 in the extraction of holes in Au@a-TiO2 photoanodes, which is not replicated by an ordinary dielectric shell. It is also demonstrated here that an ultrathin photoanode (<100 nm in maximum thickness) can efficiently drive sunlight-driven water splitting.
Noble Metal Free, Visible Light Driven Photocatalysis Using TiO2 Nanotube Arr...Pawan Kumar
Bulk g-C3N4 is an earth-abundant, easily synthesizable, and exceptionally stable photocatalyst with an electronic bandgap of 2.7 eV. Herein, the concepts of P-doping and size quantization are combined to synthesize highly fluorescent P-doped carbon nitride quantum dots (CNPQDs) with a bandgap of 2.1 eV. CNPQDs are hosted on anatase-phase and rutile-phase TiO2 nanotube array scaffolds, and examined as photoanodes for sunlight-driven water-splitting and as photocatalysts for surface catalytic reactions. Square-shaped rutile phase TiO2 nanotube arrays (STNAs) decorated with CNPQDs (CNPQD-STNA) generate 2.54 mA cm−2 photocurrent under AM1.5 G simulated sunlight. A champion hydrogen evolution rate of 22 µmol h−1 corresponds to a Faradaic efficiency of 93.2%. In conjunction with Ag nanoparticles (NPs), the CNPQD-STNA hybrid is also found to be an excellent plexcitonic photocatalyst for the visible light-driven transformation of 4-nitrobenzenethiol (4-NBT) to dimercaptoazobenzene (DMAB), producing reaction completion at a laser power of 1 mW (532 nm) while Ag NP/TNA and Ag NP/STNA photocatalysts cannot complete this transformation even at 10 mW laser power. The results point the way forward for photochemically robust, noble metal free, visible light harvesting photoacatalysts based on nanostructured heterojunctions of graphenic frameworks with TiO2.
Photovoltaics: Fundamental Concepts and novel systems
Energy levels -bands
Doping of semiconductors
Energy band alignments between different phases
Space charge layers
p-n junctions, Schottky barriers
p-n cells, Si cells, thin film cells
Schottky cells (solid and liquid junction)
p-i-n cells
Fundamental limits of photovoltaic cells
How to overcome/ bypass these limits
New generation cells (brief survey)
PV stability, efficiencies and economics
https://www.linkedin.com/in/preeti-choudhary-266414182/
https://www.instagram.com/chaudharypreeti1997/
https://www.facebook.com/profile.php?id=100013419194533
https://twitter.com/preetic27018281
Please like, share, comment and follow.
stay connected
If any query then contact:
chaudharypreeti1997@gmail.com
Thanking-You
Preeti Choudhary
The Effects of Nitrogen and Oxygen Atmosphere on the Photoconductivity of Tri...journalBEEI
Organic materials were previously used as insulators in electrical technology. These materials, however, are currently used as conductors once their photoconductivity is confirmed and studied. From the literature, it has shown that the photoconductivity of trimethyl phenyl diamine (TPD) increases in the air and decreased in the atmosphere of the vacuum. To the best of our knowledge, there is no detailed study of the effects of gas in the air that affect TPD photoconductivity. In this study we investigate the effects of nitrogen (N2) and oxygen (O2) gases on photoconductivity, degradation and residual decay of photoconductivity for thin film TPD. The results of the study show that in the atmosphere of O2, TPD produces about seven times higher photoconductivity compared to N2 conditions. It also shows that, N2 and O2 provide more effective response time during photoconductivity residual decay. Photoconductivity degradation occurs in all conditions and its recovery takes more than 65 hours.
Plenary lecture given by Prof. Hajo Freund (Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany) on September 11, 2017 in Gramado (Brazil) during the XVI B-MRS Meeting.
Efficient charge transfer induced organic/inorganic based hybrid heterojunction of Ppy/GaN nanorods for high-performance self-powered UV photodetection
Study of Measurement of luminescence life time of the Nd3+ ions in the 6-FDA/...IJERA Editor
Luminescence life time measurements of the Nd3+ ions in the 6-FDA/UVR and Al2o3 hosts were performed
using a Laser diode emitting at 800nm as the excitation source. Optical losses in both materials have been
studied and compared absorption bands of Nd3+ have been observed at 580nm ,745nm, 800nm and 870nm .
Based on which Judd- ofelt analysis has been applied to study the transition properties of Nd3+ ions in the two
hosts. Photoluminescence spectra of Nd3+ have been experimentally studied and emission around 880nm,
1060nm and 1330nm is observed, which indicates that Nd3+ ions are active in these two hosts.
Dr. Harold Weinstock presents an overview of his program, Quantum Electronic Solids, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.
Energy storage phosphors @ Phosphor Global Summit 2019Philippe Smet
Presentation on opportunities and limitations of energy storage phosphors, which can be used for glow-in-the-dark roads or safety illumination. Loss mechanisms in phosphors. Presented at the Phosphor Global Summit and Quantum Dot Forum 2019 in San Diego, La Jolla, California. March 19-21.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Study of highly broadening Photonic band gaps extension in one-dimensional Me...IOSR Journals
In this paper, we show theoretically that the reflectance spectra of one dimensional multilayer metal-organic periodic structure (1D MOPS) can be enhanced due to the addition of the organic constituents. We have used simple transfer matrix method to calculate the absorption, transmittance and reflectance of the 1D MOPS systems. The organic component like N,N’-bis-(1-naphthyl)-N,N’diphenyl-1; 1biphenyl-4; 4diamine (NPB) absorbs the light in ultra-violet, visible and infrared electromagnetic region and the structure with Ag-metal also having the tendency to absorb the light by the plasmaonic action and their refractive can be calculated from Drude equation. The reflectance spectra of multilayer 1D MOPS containing a variable number periodic of Ag/N,N’-bis-(1-naphthyl)-N,N’diphenyl-1; 1biphenyl-4; 4diamine (NPB) structure are calculated taking optical constant of NPB and Ag. The optical band gap and reflectance spectra of 1D MOPS of the considered structure is obtained in the visible and near infrared regions either with the variation of the metal layer thickness or thickness of the organic layer. From the results under investigation through TMM, tunability in the optical band gap was observed either change in thickness of the other layer 1/ or 2 or the angle of the incident. Due to optical absorption of the light in the different region of electromagnetic spectrum due to either N,N’-bis-(1-naphthyl)-N,N’diphenyl-1; 1biphenyl-4; 4diamine (NPB) or silver metal, the optical band gap of 1DMOPS shows the shift of band edges of λL and λR from ultra-violet to visible and the infrared with change the optical constant.
Cation distribution of Ni2+ and Mg2+ ions improve structure and Magnetic Prop...AI Publications
In the present work, ferromagnetic Ni is slightly substituted for diamagnetic Mg spinal ferrites. The effect of Ni doping on the structural and magnetic properties of ferrites material in the form of NixMg1-xFe2O4 (x = 0.1,0.15,0.2,0.25, .0.3,0.35) has been the study. The Sol-gel auto Combustion method used to combine these substances uses urea as fuel. Sintered samples were shown using X-ray diffraction, Fourier Transform Infrared spectroscopy (FTIR) and a vibrating magnetometer sample. X-ray diffraction revealed that all the composite samples were pure cubic spinel arrays with a Fd3m space band and a permanent lattice that varied with Ni concentrations. the distribution of Ni2 + ions and Mg2+ ions in spinel ferrites indicates various changes in parameters such as tetrahedral ionic radius (rA), octahedral ionic radius (rB), hopping length (LA and LB). Fourier Transform Infrared (FT-IR) simulations showed wire vibration at the tetrahedral site and Octahedral site. spinel ferrites M-H curves are recorded at room temperature indicating normal hysteresis loop indicating the magnetic field.
Kilohertz-Rate MeV Ultrafast Electron Diffraction for Time-resolved Materials...Yi Lin
Ultrafast electron diffraction (UED) enables direct insight into structural dynamics of solids. Relativistic MeV-scale electron beams yield access to high-momentum scattering and preserve beam coherence, yet their application at high repetition rates for high-sensitivity UED has been limited. We discuss the High Repetition-rate Electron Scattering (HiRES) instrument at Berkeley Lab and its first applications to UED of metallic films and quantum materials. HiRES employs a state-of-the-art photoinjector with RF bunch compression to generate high-brightness, relativistic 0.75 MeV electron pulses with up to 105-106 el./pulse and with highest achievable coherence length of 10 nm. The resulting high momentum range (±10 Å-1) yields access over multiple Brillouin zones. The sub-500 fs electron pulses are provided at 0.1-250 kHz repetition rate, and combined with optical pumping via a 1.03 µm fiber amplifier enable UED of cryogenically cooled materials. We will show examples of first experiments including transient Debye-Waller dynamics in ultrathin metals at kHz repetition rate as well as studies of charge density waves in 2D materials.
Work at LBNL was supported by the DOE Office of Basic Energy Sciences.
Similar to Mid-IR Pulse Generation Using Cr2+:ZnSe (20)
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Generating a custom Ruby SDK for your web service or Rails API using Smithyg2nightmarescribd
Have you ever wanted a Ruby client API to communicate with your web service? Smithy is a protocol-agnostic language for defining services and SDKs. Smithy Ruby is an implementation of Smithy that generates a Ruby SDK using a Smithy model. In this talk, we will explore Smithy and Smithy Ruby to learn how to generate custom feature-rich SDKs that can communicate with any web service, such as a Rails JSON API.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
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All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
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Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
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- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
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2. OUTLINE
• Applications of mid-IR pulse generation
• Review of optical properties
• Material properties
• Comparison of Ti3+:Al2O3 and Cr2+:ZnSe
1
• Benefits and considerations
3. APPLICATIONS
• mid-IR frequency combs
• Non-invasive medical diagnosis
• Non-destructive chemical probing
• Free space communication
• Environmental/atmospheric sensing
DeLoach, Page, Wilke, Payne, Krupke. IEEE J. Quant. Elec. 32, 6 (1996).
2
• Access to important spectroscopic regions through
OPA/OPO
6. t
BROAD SE BANDWIDTH
Gauthier and Boyd. “Fast Light, Slow Light and Optical Precursors: What Does It All Mean?” Photonics Spectra (2007).
5
Schematic of interference of different wavelengths to produce a pulse.
13. Host Crystal
Active Ions
ANATOMY of an ION DOPED CRYSTAL
Yoshida. “Process for producing a heavily nitrogen doped ZnSe crystal.” US Patent 5891243. Feb 11, 1998.
12
Schematic of a host crystal with two different active ion dopants.
15. Electronic Field
STARK EFFECT SPLITTING
Courtney, Spellmeyer, Jiao, Kleppner Phys Rev A 51 (1995).
14
Schematic of splitting of electronic energy levels in an electronic field.
22. DAMAGE
• Thermal damage
• high thermal conductance
• mechanically stable at high temperatures
• chemically stable at high temperatures
• Photo-reactivity
21
• chemically stable under exposure to high intensity light
23. MATERIAL PROPERTIES
FOR
• BROAD SE BANDWIDTH
• HIGH INTENSITY
• quantum efficiency
• stimulated emission cross section
• STABILITY
22
• Perturbations
• Damage
29. CHALLENGES
• Still under development
• Expensive optics
• Pulses are not near the theoretical limit yet
28
• Cr2+:ZnSe is difficult to manufacture
30. put characteristics in CW (13W and developed commercial, quantitative (accuracy o
issues Cr:ZnSe [40], 10W Cr:ZnS [41]) and gainmes of operation (20mJ Cr:ZnSe [42], better than 3%) and fast thermo-diffusion proce
dopant is 4.7 mJ Fe:ZnSe [43]).
with suppressed sublimation in Zn/Cd and Se/S sublatt
crystals are uniformly doped through the thickness of up
low scattering loss of 1-2% per cm for samples with
Consistently high optical quality of fabricated thermo
Using post-growth thermal
Fe:ZnSe polycrystals with low depolarization factor ena
diffusion:
Cr:ZnSe femtosecond oscillator [38], ultra-broad tunability
• Difficult to predict final for CW lasers based on polycrystalline Cr:ZnSe and Cr:Z
dopant levels
up-to-date output characteristics in CW (13W Cr:ZnSe
• Dopant is not
switched regimes of operation (20mJ Cr:ZnSe [42], 4.7 mJ
MANUFACTURING
homogeneous
•
Host crystal sublimation
•
Poor repeatability
Recent results:
•
“uniform” doping at 7mm
depth
• Scattering loss Cr:ZnSe1Thermo-diffusion doped of
and Cr:ZnS crystals. Cr:ZnS crystals with undoped
2 %/cm
ere fabricated by post-growth directed diffusion of active ions in the crystal.
29
TM doped II-VI ceramics
antage of laser ceramics Mirov,in advanced ceramic processing enabling affordable
Mirov, Fedorov, Martyshkin, Moskalev, is Gapontsev. Opt. Mat. Exp. 1, 5 (2011).
Thank you for having me speak on the properties of chromium doped zinc selenide that make fast pulse generation possible.I hope to illuminate some of the potential benefits of the material as well as important differences from other ultrafast source materials.
I will first explain why ultrafast mid-IR sources are of interest,Then I will give a brief review of the propertiesof Kerr lens mode-locked ultrafast laser sources.Then I’ll move on to describe the spectroscopic, chemical and physical material mechanisms that make ultrafast pulse generation possible.It will then be useful to show how these processes combine in titanium doped sapphire to create ultrafast pulses;and how spectroscopic differences manifest as pulse differences in other materials, for example chromium doped zinc selenide.
Identify and quantify molecules absorbing in this regionNon-intrusive medical diagnosticsnon-destructiveIndustrial process controlEnvironmental monitoring/atmospheric sensingWavelength longer than 3mm needed, many organic compounds have vibronic transitions in this region. Cr:CdSe goes to 3.6Free space communicationOil prospectingInfrared countermeasures (DOD)Monitoring of munitions disposal (DOD)Stand-off detection of explosion hazards (DOD)[DeLoach et al, IEEE J. Quantum Electron. 32, 6 (1996).]Direct & overtone spectroscopyMolecular fingerprint region<<WHY ARE SHORT PULSES NECESSARY? HIGHER RESOLUTION?>><<ANY APPLICATIONS THAT ARE NOT CHEMICAL?>>
Cr:CdSe (2.26-3.61)Fe:ZnS (3.49-4.65)
There are three key optical requirements to generate short pulses using Kerr lens mode locking:a broad optical bandwidthhigh pulse intensityand laser cavity stability.
We have seen this image a few times in this class, but here it is again.Broad bandwidth is required to localize the pulse by interference.Constructive interference must be present between frequencies at one time to create a pulseDestructive interference must occur to minimize noise outside of the pulse.To create maximum constructive interference, each frequency must be in phase at one time—this is called “mode locking”.(add x axis)
These short length, high intensity pulses can be preferentially selected using the Kerr lens effect, described by this equation.The Kerr lens effect describes the different refractive index of a material experienced by high intensity light:Because the zeroth-order term is significantly larger than the second-order termThe refractive index is dependent on optical intensity,More intense light will be focused into the laser cavityLess intense light will be rejected.n2 = 1.2ee-18 m2/W [Cizmeciyan et al, apphys b 106 (2012).
This figure shows the use of the Kerr lens effect in selecting pulses.The Kerr lens effect can be used to preferentially select high intensity pulses and exclude continuous, random phase light.This process is called “Kerr lens mode-locking.”To use Kerr lens mode-locking, the laser source materials must withstand these high intensity pulses, so they must be very stable
This schematic shows a laser cavity supporting several frequencies as is necessary to generate ultrafast pulses.Because the cavity must be properly aligned to stimulate emission of pulses and mode lock the different frequencies, the lasing material must be stable under conditions of operation. This is especially challenging because the circulating pulse has very high intensity, making damage prevention important.
With bandwidth, intensity and cavity stability in mind, we will now move into the material properties that make pulse generation possible.
Looking at laser sources in this figure, there are a lot to choose from.Line sources like Ruby would not be able to generate short pulses because they do not emit at a wide enough range of frequencies.
While the industry standard, Ti:sapph, emits at a range of 460 nm. What mechanism allows Ti:sapph to support such a broad bandwidth?Looking at all of the broad band sources, about 30% of the materials are ion doped crystals. These crystals are good candidates for ultrafast pulse generation because they canparticipate in Kerr lens mode-locking and withstand high intensity pulses better than their dye and gas counterparts.
This figure shows the structure of an ion doped crystal. An ion doped crystal consists of:an emitting active ion—like chromium, titanium, or iron—suspended in the host material—anda transparent host crystal—like sapphire, borosilicate, zinc selenide—corresponding to the emission wavelength.
This figure shows a standard, four level laser.The electronic orbitals that are available within the active ion determine at which frequencies the material will absorb and emit radiation. To emit a wide bandwidth of different frequencies, a range of different energy states must be present at the first and second energy levels.
This figure shows the D orbitals of hydrogen. In the active ion, just like in hydrogen, the first and second laser levels also have multiple orbitals of the same energy. These are called degenerate orbitals. Like in hydrogen, these orbitals all have different shapes.If those orbitals are subjected to an electric field, they will experience different changes in potential energy.This will cause the energy degenerate orbitals to split into orbitals of different energy.----- Meeting Notes (5/14/13 13:45) -----The stark effect can be used to increase these energy levels by splitting degenerate energy levels.
Combining all of these effects in our doped crystal, the crystal host acts as an effective electric field.The first and second levels of the active ionare split into multiple energy levelswhich will have many possible emission energiesleading to a broad distribution of frequencies of emitted light and a broad bandwidth
<<second order non linearity for ZnSe (pV/m) = 30>>
Quantum efficiency is effected by these processes and is a good indicator of the total<<STIUMLATION/DIPOLE TRANSITION STATE COUPLING?>>
Low maximum phonon frequency: decreases non-radiative decay rate and increases quantum yield what is the mechanism for that?Energy migration due to (a) resonant transitions (b) self-quenching by cross-relaxation and (c) self-quenching by up-conversion. These processes are nearly absent in Cr2+:ZnSe.“Another important advance is reflected by numerous articles on processes between excited state levels as can be seen in Fig. 6 in which migration due to resonant transitions, self-quenching by cross-relaxation, and self-quenching by up-conversion mechanisms are shown. This recent discovery of the infrared tunability seen in both Fe2+-doped ZnSe … is the consequence of such advance in the infrared range with selenides … .”
Stability is a combination of minimizing perturbations to the system during use and preventing damage of the components.
Small changes to the system during use are mostly due to temperature change.Prevent thermal changes to the refractive index of the crystal (dn/dT) that cause thermal lensing and would change optical path length<<Photobleaching?>>
How does chromium doped zinc selenide compare to industry standard?
Note that this range in wavelength is not a wide range in frequency: DO THE MATH (~1/10th the frequency bandwidth)Bandgap for ZnSe is 2.8 eVTetrehedral coordination of the active ions gives ~twice smaller crystal field splittingSapphire is octrahedral<<strong electron-phonon coupling significant broadening?>>
1.973-3.339 mm reported by Mirov et al1.880-3.349 mm reported by cizmeciyan
Vibrational lifetimes are ~100fs (except in the gas phase)Heavy anions provide low energy optical phonon cut-off, non-radiative decay via phonons is less likely and gives high fluorescence yieldMax phonon for ZnSe is 250 cm-1
18 is a reasonably high thermal conductivity and can be workable.70 is a relatively high thermal lensing parameter, does need to be given some attention by proper thermal management but can generally be compensated for with low thermal load due to absence of excited state absorption and up-conversion in ZnSe, as illustrated by optical quantum efficiency
Expensive optics- Dispersion compensation using CaF2 and MgF2, slabs of BK7 and YAG
DopingDuring growth (physical vapor transport) [Su et al j. cryst. Growth 207, 1-2 (1999).; Rai et al. J applphys 83, 11 (1998); Korostelin et al j alloy comp 371, 25-30 (2004)]Progress in PVT, but never better than post growth diffusionDifficult to achieve homogenous impurity distribution with predictable concentration, especially at high doping conc.After growth by diffusion8.35ee18 ion/mLMetal film deposited on the surface900-1100 deg. C, 7-10 daysCr/Fe or vapor phase annealingSeal metal and substrate in different parts of low pressure ampouleHeat metal to ionizeDiffuse into substrateDrawbacksDifficult to fabricate crystals with exact dopant levelsNon-uniform dopingSublattice sublimationPoor repeatabilityMirov et al opt. mat. Exp 1,5 (2011) reports“Uniform” doping at 7mm depthLow scattering loss 1-2%/cmZnSe crystalstwin-type stacking faults (interlayers of hexagonal phase in the cubic matrix) 0-2% of the crystalNo twins observed in Cr2+ doped crystals at minimum concentration of 3ee19 /mL [Kulakov et al, Neorg. Mater. 12, 10 (1976).Cz growth requires high T & P, not commercially viableBridgman growth—melt & cool with seed crystal—sometimes has uncontrolled contamination & leads to parasitic absorptions.
Thank you for your time.
Hosts are chosen to transmit the stimulated emission, not to emit, so they need to have a wide range of transmittance in the region of stimulated emission. The electronic transitions that lead to absorption and emission take place within the active ion.<<Outside of the transmission region, absorption is usually dissipated as phonon vibration in the host rather than being reemited. Some resonant transitions may exist, like the peaks in borosilicate.>>----- Meeting Notes (5/14/13 13:45) -----Pause for slides, introduce graphs.