This document discusses using pair distribution function (PDF) analysis on a standard laboratory X-ray diffraction system to analyze nanocrystalline and amorphous materials. PDF analysis provides structural information about short- and long-range atomic ordering. Experiments were conducted using different samples, including silicon carbide, nanocrystalline anatase, silicon powder, and vanadium oxide xerogel. The results demonstrate that meaningful PDF profiles can be obtained from laboratory X-ray sources, allowing extraction of structural information for comparison with literature data.
Beyond the Elements XRD Mineralogy & XRF Analysis for Advanced Mud LoggingOlympus IMS
More information on Olympus XRF and XRD solutions: http://bit.ly/1pZ3zBo
A presentation from the webinar Beyond the Elements XRD Mineralogy & XRF Analysis for Advanced Mud Logging.
Learn how XRD and XRF analyzers help maximize the efficiency of drilling operations by quickly finding commercially viable target zones for better production and improved ROI.
Understand rock type indicating oil and gas bearing zones and identify mineralogical trends to keep the drill in the shale pay zone with real-time XRD and XRF analysis.
On-site analysis provides faster results and reduces costs from sending fewer samples to the outside lab. We will review techniques for on-site analysis to make informed geo-steering decisions.
Watch the webinar associated with this presentation: http://bit.ly/1ohxid8
Contact us: http://bit.ly/1rDmq94
Sign up for our newsletter: http://bit.ly/1j5FOTy
X ray
Md. Waliullah Wali
Dept. of pharmacy
Southeast University
Outline
XRD
X-ray diffraction (XRD) is an analytical technique looking at X-ray scattering from crystalline materials. Each material produces a unique X-ray "fingerprint" of X-ray intensity versus scattering angle that is characteristic of it's crystalline atomic structure.
X-ray diffraction procedures
apply only to crystalline
Materials.
Principles of XRD
X-ray diffraction is based on constructive interference of monochromatic X-rays and a crystalline sample.
The interaction of the incident rays with the sample produces constructive interference (and a diffracted ray) when conditions satisfy Bragg's Law (nλ=2d sin θ).
XRD Techniques
XRD Techniques
Applications of XRD
Limitations of XRD
XRF
X-Ray Fluorescence is defined as “The emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays. The phenomenon is widely used for elemental analysis.”
X-ray fluorescence procedures
applied to the material
in any physical state,
solid, liquid and gas.
Principles of XRF
The XRF method depends on fundamental principles that are common to several other instrumental methods involving interactions between electron beams and X-rays with samples, including, X-ray spectroscopy (e.g. SEM – EDS), X-ray diffraction (XRD) and wavelength dispersive spectroscopy (microprobe WDS).
XRF Techniques
Applications of XRF
Advantages of XRF
Limitation of XRF
0
References
1. Elements of physical chemistry by S Glasstone
2. Atkins physical chemistry
3. Pharmaceutical chemistry by LG Chattem
4. Brady, John B., and Boardman, Shelby J., 1995, Introducing Mineralogy Students to X-ray Diffraction Through Optical Diffraction Experiments Using Lasers. Jour. Geol. Education, v. 43 #5, 471-476.
5. Brady, John B., Newton, Robert M., and Boardman, Shelby J., 1995, New Uses for Powder X-ray Diffraction Experiments in the Undergraduate Curriculum. Jour. Geol. Education, v. 43 #5, 466-470.
6. Buhrke, V. E., Jenkins, R., Smith, D. K., A Practical Guide for the Preparation of Specimens for XRF and XRD Analysis, Wiley, 1998.
Beyond the Elements XRD Mineralogy & XRF Analysis for Advanced Mud LoggingOlympus IMS
More information on Olympus XRF and XRD solutions: http://bit.ly/1pZ3zBo
A presentation from the webinar Beyond the Elements XRD Mineralogy & XRF Analysis for Advanced Mud Logging.
Learn how XRD and XRF analyzers help maximize the efficiency of drilling operations by quickly finding commercially viable target zones for better production and improved ROI.
Understand rock type indicating oil and gas bearing zones and identify mineralogical trends to keep the drill in the shale pay zone with real-time XRD and XRF analysis.
On-site analysis provides faster results and reduces costs from sending fewer samples to the outside lab. We will review techniques for on-site analysis to make informed geo-steering decisions.
Watch the webinar associated with this presentation: http://bit.ly/1ohxid8
Contact us: http://bit.ly/1rDmq94
Sign up for our newsletter: http://bit.ly/1j5FOTy
X ray
Md. Waliullah Wali
Dept. of pharmacy
Southeast University
Outline
XRD
X-ray diffraction (XRD) is an analytical technique looking at X-ray scattering from crystalline materials. Each material produces a unique X-ray "fingerprint" of X-ray intensity versus scattering angle that is characteristic of it's crystalline atomic structure.
X-ray diffraction procedures
apply only to crystalline
Materials.
Principles of XRD
X-ray diffraction is based on constructive interference of monochromatic X-rays and a crystalline sample.
The interaction of the incident rays with the sample produces constructive interference (and a diffracted ray) when conditions satisfy Bragg's Law (nλ=2d sin θ).
XRD Techniques
XRD Techniques
Applications of XRD
Limitations of XRD
XRF
X-Ray Fluorescence is defined as “The emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays. The phenomenon is widely used for elemental analysis.”
X-ray fluorescence procedures
applied to the material
in any physical state,
solid, liquid and gas.
Principles of XRF
The XRF method depends on fundamental principles that are common to several other instrumental methods involving interactions between electron beams and X-rays with samples, including, X-ray spectroscopy (e.g. SEM – EDS), X-ray diffraction (XRD) and wavelength dispersive spectroscopy (microprobe WDS).
XRF Techniques
Applications of XRF
Advantages of XRF
Limitation of XRF
0
References
1. Elements of physical chemistry by S Glasstone
2. Atkins physical chemistry
3. Pharmaceutical chemistry by LG Chattem
4. Brady, John B., and Boardman, Shelby J., 1995, Introducing Mineralogy Students to X-ray Diffraction Through Optical Diffraction Experiments Using Lasers. Jour. Geol. Education, v. 43 #5, 471-476.
5. Brady, John B., Newton, Robert M., and Boardman, Shelby J., 1995, New Uses for Powder X-ray Diffraction Experiments in the Undergraduate Curriculum. Jour. Geol. Education, v. 43 #5, 466-470.
6. Buhrke, V. E., Jenkins, R., Smith, D. K., A Practical Guide for the Preparation of Specimens for XRF and XRD Analysis, Wiley, 1998.
Invited lecture of the Simposium N "Surface Engineering - functional coatings and modified surfaces" at the XIII SBPMat (Brazilian MRS) meeting, in João Pessoa (Brazil). The lecture took place on September 30th, 2014.
The speaker was Professor Christoph Genzel, from the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), in Germany, where he heads the Department of Microstructure and Residual Stress Analysis and he coordinates a group of diffraction and scattering. Genzel is also Associate Professor at the Technische Universität Berlin.
Abstract
Terahertz sub-surface imaging offers an effective solution for surface and 3D imaging because of minimal
sample preparation requirements and its ability to “see” below the surface. Another important property is the ability
to inspect on a layer-by layer basis via a non-contact route, non-destructive route. Terahertz 3D imager designed
at Applied Research and Photonics (Harrisburg, PA) has been used to demonstrate reconstructive imaging with a
resolution of less than a nanometer. Gridding with inverse distance to power equations has been described for 3D
image formation. A continuous wave terahertz source derived from dendrimer dipole excitation has been used for
reflection mode scanning in the three orthogonal directions. Both 2D and 3D images are generated for the analysis
of silver iodide quantum dots’ size parameter. Layer by layer image analysis has been outlined. Graphical analysis
was used for particle size and layer thickness determinations. The demonstrated results of quantum dot particle
size checks well with those determined by TEM micrograph and powder X-ray diffraction analysis. The reported
non-contact measurement system is expected to be useful for characterizing 2D and 3D naomaterials as well as for process development and/or quality inspection at the production line.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Analysis Of Carbon Nanotubes And Quantum Dots In A Photovoltaic Device Slide ...M. Faisal Halim
Francis' presentation to Louis Stokes Association for Minority Participation. Since I co-authored this work I think I have the right to a copy. I was the graduate student Francis was working with.
Design of a Selective Filter based on 2D Photonic Crystals Materials IJECEIAES
Two dimensional finite differences temporal domain (2D-FDTD) numerical simulations are performed in cartesian coordinate system to determine the dispersion diagrams of transverse electric (TE) of a two-dimension photonic crystal (PC) with triangular lattice. The aim of this work is to design a filter with maximum spectral response close to the frequency 1.55 μm. To achieve this frequency, selective filters PC are formed by combination of three waveguides W 1 K A wherein the air holes have of different normalized radii respectively r 1 /a=0.44, r 2 /a=0.288 and r /a= 0.3292 (a: is the periodicity of the lattice with value 0.48 μm). Best response is obtained when we insert three small cylindrical cavities (with normalized radius of 0.17) between the two half-planes of photonic crystal strong lateral confinement.
This is the project report for my internship at HBCSE-TIFR. The project describes a low-cost method for analysing the spectrum of LEDs and determining the wavelength.
Optical Fiber Device For Coupling A Composite-Type Optical Fiber Scope And Pu...IJRES Journal
An optical fiber coupling device for plant maintenance was developed. Pulse laser processing with the coupling device can serve three functions: spectral analysis, laser processing, and visual observation. All of these functions can be operated remotely via a single composite-type optical fiber scope. The optical fiber scope enables both laser energy delivery and target image transmission with simultaneous counter-propagation, which can make a probing device very compact. Therefore, this device would permit laser processing in a narrow space, allowing in situ monitoring for plant maintenance. The functionalities of the coupling device for cleaning a metal surface and for remote spectral analysis were tested and reported. Finally, possible applications and desired technologies for the coupling device were discussed, including its use in a nuclear power plant sensing system for detecting seismic vibration.
Consistently High Voc Values in p-i-n Type Perovskite Solar Cells Using Ni3+-...Pawan Kumar
Leading edge p-i-n type halide perovskite solar cells (PSCs) severely underperform n-i-p PSCs. p-i-n type PSCs that use PEDOT:PSS hole transport layers (HTLs) struggle to generate open-circuit photovoltage values higher than 1 V. NiO HTLs have shown greater promise in achieving high Voc values albeit inconsistently. In this report, a NiO nanomesh with Ni3+ defect grown by the hydrothermal method was used to obtain PSCs with Voc values that consistently exceeded 1.10 V (champion Voc = 1.14 V). A champion device photoconversion efficiency of 17.75% was observed. Density functional theory modeling was used to understand the interfacial properties of the NiO/perovskite interface. The PCE of PSCs constructed using the Ni3+-doped NiO nanomesh HTL was ∼34% higher than that of conventional compact NiO-based perovskite solar cells. A suite of characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy, intensity-modulated photocurrent spectroscopy, intensity-modulated photovoltage spectroscopy, time-resolved photoluminescence, steady-state photoluminescence, and Kelvin probe force microscopy provided evidence of better film quality, enhanced charge transfer, and suppressed charge recombination in PSCs based on hydrothermally grown NiO nanostructures.
Ultrafast response of metal-semiconductor hybrid.pptxSabinaGurung12
This thesis presents an extensive study of self-organizatized synthesis of hybrid
nanostructure and their characterization using a combination of spectroscopic and microscopic
techniques, supported by theoretical modelling. Apart from the various potential applications of the
hybrid nanostructures reported, this thesis also provides an insight on the synergistic interaction
between Ag NP and CdTe QD. The future interest of this work involves utilization of these hybrid
nanostructure colloid for various applications like in optoelectronics and solar cells by transforming
the colloidal sample into thin films.
C3N5: A Low Bandgap Semiconductor Containing an Azo-linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction down to 1.76 eV. XRD, He-ion imaging, HR-TEM, EELS, PL, fluorescence lifetime imaging, Raman, FTIR, TGA, KPFM, XPS, NMR and EPR clearly show that the properties of C3N5 are distinct from pristine carbon nitride (g-C3N4). When used as an electron transport layer (ETL) in MAPbBr3 based halide perovskite solar cells, C3N5 outperformed g-C3N4, in particular generating an open circuit photovoltage as high as 1.3 V, while C3N5 blended with MAxFA1–xPb(I0.85Br0.15)3 perovskite active layer achieved a photoconversion efficiency (PCE) up to 16.7%. C3N5 was also shown to be an effective visible light sensitizer for TiO2 photoanodes in photoelectrochemical water splitting. Because of its electron-rich character, the C3N5 material displayed instantaneous adsorption of methylene blue from aqueous solution reaching complete equilibrium within 10 min, which is significantly faster than pristine g-C3N4 and other carbon based materials. C3N5 coupled with plasmonic silver nanocubes promotes plasmon-exciton coinduced surface catalytic reactions reaching completion at much low laser intensity (1.0 mW) than g-C3N4, which showed sluggish performance even at high laser power (10.0 mW). The relatively narrow bandgap and 2D structure of C3N5 make it an interesting air-stable and temperature-resistant semiconductor for optoelectronic applications while its electron-rich character and intra sheet cavity make it an attractive supramolecular adsorbent for environmental applications.
Few-mode optical fiber surface plasmon resonance sensor with controllable ra...IJECEIAES
A few-mode optical fiber surface plasmon resonance sensor with graphene layer is investigated, firstly, with the aim of studying the behavior of the guided modes and, secondly, with the aim of determining the range of the measured refractive index for some selected few-mode fibers. The results show that as the number of modes propagated in the fiber increases, the maximum sensitivity of a particular mode decreases while the range of the measured refractive index of that mode increases. Also, it is shown that the range can be easily tuned with sensitivity consideration by only adjusting the operating wavelength without any modification of the sensor, which is desirable from practical point of view. In addition, it is shown that the core diameter of the fiber should be chosen according to sensitivity and range needing, where a compromise between them must be found. The study presented in this paper can significantly help in developing new sensing techniques, such as multi-parameter sensing, by monitoring the various responses of the modes. Also, it can be used to customize the sensor for specific sensing applications in various fields, especially to measure refractive indices in subranges of 1.38 to 1.46.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Comparative structure of adrenal gland in vertebrates
Pa nalytical pdf
1. Pair distribution
function analysis
The Analytical X-ray Company
Total scattering experiments
using high-energy X-rays on
a laboratory system
Summary
Analyzing powder diffraction data
of nanocrystalline and amorphous
materials using the atomic pair
distribution function (PDF) method
provides useful information about
the long- and short-range ordering
of the atoms in the materials. We
have developed the application
of PDF analysis on a standard
laboratory system employing an
X-ray tube with either a silver or a
molybdenum anode as X-ray source.
Data obtained from a variety of
samples are shown. Meaningful
results have been achieved, that
allowed extracting structural
information for comparison with
data reported in literature.
Introduction
Recent years have shown an increased
interest in the study of nanocrystalline
materials due to their specific properties
for application in e.g. semiconductors,
pharmaceuticals and polymers.
Structural information about these
materials is present as broad, not well
defined features in a diffractogram.
Analysis of nanomaterials therefore
requires a total scattering approach,
including both Bragg peaks and diffuse
scattering. One of the most promising
analytical methods used is atomic pair
distribution function (PDF) analysis.
Originally, this method was used to
study primarily amorphous and highly
disordered materials. More recently,
it has been used for the analysis of
nanostructured materials. Since the
method requires short wavelengths
to obtain high resolution in real space
(well defined interatomic distances),
often the measurements are performed
at synchrotron facilities, making use of
both the high photon energies and the
high photon flux that these facilities
offer.
We have investigated the possibility to
apply the pair distribution technique
on an in-house system, using Ag or
Mo Kα radiation. This application note
describes typical results on nanocrystals,
liquids and amorphous materials.
G[Å]-2
r [Å]
10 2 3 4 5 6
XRD APPLICATION NOTE
Schematic representation of the construction
of the atomic pair distribution function from a
square array of atoms [2]. The colored circles (a)
indicate the distance from a central atom where
a neighboring atom can be found. The arrows
indicate the corresponding peaks in the pair
distribution function.
(a)
(b)
2. Pair distribution function analysis
The pair distribution function G(r) describes the probability of finding two atoms separated by a distance r in the
material under investigation. The PDF method extracts structure-related information from powder diffraction data [3].
Since the technique takes both Bragg and diffuse scattering into account, it provides information not only about the
long-range (>10 nm) atomic ordering but also about the short-range ordering in materials. The method is performed in
the following steps:
(i) the diffraction pattern is corrected for background (using a separate diffraction measurement of an empty sample
container), Compton scattering, detector dead time, absorption, diffraction geometry and polarization;
(ii) the corrected X-ray diffraction data is scaled into electron units and the reduced structure function [4] is calculated;
(iii) the structure function is Fourier transformed to obtain the atomic pair distribution function:
G(r) = 4πr (ρ(r) - ρ0)
in which ρ(r) is the local atom number density, and ρ0 is the mean atom number density.
Since the method does not assume periodicity in the material, it is widely applied for the study of nanocrystalline and
amorphous materials. The data can be used for full-profile fitting to refine structural models [5].
Empyrean goniometer
with programmable
divergence slit and
incident beam anti-
scatter slit, capillary
spinner, programmable
receiving slit with
programmable
anti-scatter slit and
scintillation detector
PreFIX mounting
The optics and sample
stage are designed
according to the PreFIX
concept; they are
interchangeable with all
other available modules
for Empyrean without
the need for
realignment. The
capillary spinner stage
uses a goniometer head
to allow precise
alignment of the
capillary tube on the
goniometer axis.
Beam path of the used configuration
Instrumental configurations
X-ray diffraction measurements were
performed on a PANalytical Empyrean
system equipped with a programmable
divergence slit, a capillary spinner, a
dedicated anti-scatter device, and either
X’Celerator detector or a scintillation
detector with a programmable
receiving slit. The X-ray source was a
tube with either silver or molybdenum
anode delivering Kα radiation with a
wavelength of 0.0561 or 0.0709 nm,
respectively.
Additional shielding was applied to
the optical path in order to achieve a
feature-free background.
The samples were prepared in glass
capillaries with a diameter of 2 mm.
Scans along the 2θ axis were made up to
an angle of 160 degrees corresponding
to a scattering vector Q of 22 A-1 when
a silver anode is used. The scattering
vector is given by:
Q = 4π sinθ / λ
Initial data treatment, including
background subtraction and optional
Kα2 stripping, was done using X’Pert
HighScore.
For PDF analysis and fitting, we used the
software RAD [6] and PDFgui [5].
Experimental
setup Instrument Empyrean
X-ray tube Empyrean Tube with silver (Ag) or molybdenum (Mo)
anode, long fine focus
Incident beam optics Divergence slit with incident beam anti-scatter slit and
rhodium (Rh) or zirconium (Zr) beta-filters, focusing
beam X-ray mirrors
Sample stage Capillary spinner
Reflection-transmission spinner
Flat sample stage
Diffracted beam optics Programmable receiving slit with programmable
anti-scatter slit or a dedicated anti-scatter device
Detector X’Celerator, scintillation detector
Scan parameters Typically 2 - 160° 2θ, 0.06° step size
Total scan time 8-24 hours depending on the material and the
configuration used for the experiment
3. Results and
discussion
Intensity[counts]F(Q)[Å-1]
(Q) [Å-1]
2 theta [deg.] (Ag radiation)
62500
40000
22500
10000
2500
0
10 20 30 40 50
Empty container
Experiment data
60 70 80 90 100 110 120 130
-20
-10
0
10
20
30
40
0 5 10 15 20
Intensity[counts]F(Q)[Å-1]
(Q) [Å-1]
2 theta [deg.] (Ag radiation)
62500
40000
22500
10000
2500
0
10 20 30 40 50
Empty container
Experiment data
60 70 80 90 100 110 120 130
-20
-10
0
10
20
30
40
0 5 10 15 20
Radial distance [Å]
10
5
0
-5
10 20 30 40 50 60
Gdiff
Gobs
Gcalc
G(r)[Å-2]
Radial distance [Å]
Gdiff
Gobs
Gcalc
10
5
0
-5
5 10 15 20 25
a
b
c
d a: ¼<111>
b: ½<110>
c: <100>
d: ¼<331>
Gdiff
Gobs
Gcalc
G(r)[Å-2]
Samples of different nature – crystalline,
nanocrystalline, amorphous solid
and liquid – were selected to test
the applicability of PDF analysis on a
standard XRD system. The results of
these experiments are described below.
Silicon carbide
Figure 1a shows a diffraction pattern
of silicon carbide powder in a capillary,
together with a measurement of an
empty capillary. The reduced structure
function obtained from the corrected
intensity data is shown in Figure 1b.
After Fourier transformation the PDF as
shown in Figure 2 was obtained. Figure
2b shows the short distances of the PDF
in more detail. The maxima in this graph
could be identified as the interatomic
distances Si-C, Si-Si and C-C, derived
from the sphalerite crystal structure
of SiC [6]. The relation between the
orientation and the interatomic
distances in SiC is shown in Table 1.
Figure 1. (a) XRD
measurement and
(b) reduced structure
function of silicon
carbide
Figure 2. Experimental
(circles) and calculated
atomic PDF (red line)
of SiC
SiC crystal
structure
Table 1. Interatomic distances of SiC calculated
determined from the experimental PDF (Fig.2)
(a)
(a)
(b)
(b)
Atoms Orientation Interatomic
distance [Å]
Si - C ¼ <111> 1.89
Si - Si, C - C ½ <110> 3.08
Si - C ¼ <311> 3.61
Si - Si, C - C <100> 4.36
Si - C ¼ <331> 4.75
Si - Si, C - C ½ <211> 5.34
4. Variable counting time
Measurements performed for PDF
analysis typically require long-range
scans up to high 2θ angles, where the
diffracted intensities are low. Variable
counting time (VCT) methods can be
applied to spend longer counting times
at the high-angle, low-intensity region
of the diffractogram at the cost of
time spent on the low-angle region.
Schematically the redistribution of
measurement times is shown in Figure 3.
The total measurement time is the same
for both situations.
In order to investigate the improvement
of data quality at high Q-values,
measurements were performed on
nanocrystalline anatase (TiO2) with an
average particle size of 15 nm using
constant and variable measurement
times according to the scheme given in
Figure 3. The resulting diffractograms
and reduced structure functions are
shown in Figure 4 and 5 respectively.
Figure 3. Constant counting time (left) and variable counting time (right) as a function of 2θ angle
Figure 4. XRD
measurements on
nanocrystalline anatase
measured using (a)
constant counting
time and (b) variable
counting time
Results and
discussion ctd.
(b)
20 40 60 80 100 120 140
20 40 60 80 100 120 140
2theta [deg.]
0
50000
100000
150000
200000
Intensity[counts]
2theta [deg.]
0
10000
20000
30000
Intensity[counts]
(a)
5. Figure 5. Reduced
structure functions
of anatase, measured
using variable and
constant counting
times
The noise level at high Q-values of the
variable counting time measurement
is improved in comparison with the
constant counting time measurement
allowing the observation of additional
structure-related features. No reduction
in data quality has been observed in
the low Q-range. The experimental PDF
derived from the VCT experiment is in
good agreement with the calculated
PDF, as is shown in Figure 6.
Anatase - constant counting time
-5
0
5
10
0 5 10 15 20
Anatase - variable counting time
-5
0
5
10
0 5 10 15 20
F(Q)[Å-1]F(Q)[Å-1]G(r)[Å-2]
Radial distance [Å]
4
2
0
-1
0 10 20 30 40
Gdiff
Gobs
Gcalc
3
1
-2
-3
Figure 6.
Experimental
(circles) and
calculated atomic
PDF (red line) of
nanocrystalline
anatase
6. Focusing mirrors for high-energy X-rays
(Ag and Mo)
The graded multilayer focusing X-ray
mirror is a beam conditioner, which
is able to convert the divergent X-ray
beam from a tube in line focus position
to an intense monochromatic beam that
is focused onto the goniometer circle.
Experimental configurations for PDF
analysis using slit and mirror optics are
graphically compared in Figure 7 and 8.
Results and discussion ctd.
Figure 8: configuration with a focusing X-ray mirror using convergent X-ray beam
Sample in horizontal
orientation
Line- or point
detector - X’Celerator
or scintillation counter
Line- or point
detector - X’Celerator
or scintillation counter
Figure 7: standard configuration using divergent X-ray beam
7. The performance of the focusing X-ray
mirror for diffraction measurements in
transmission geometry (including PDF
analysis) was tested using silicon powder
(NIST SRM 640b) prepared in a 0.3 mm
glass capilary. Experiments showed that
the intensity and angular resolution
of the diffraction data collected with
the focusing mirror for Mo radiation
are suitable for PDF analysis as well as
traditional diffraction applications, such
as phase analysis.
Figure 9: silicon 640b: raw measurements. Data collected using a focusing mirror for Mo radiation
(λ = 0.7093 Å)
Figure 10: experimental PDF of silicon (blue dots) compared with a calculated PDF using the known
structure of Si (red line).
Figure 11: angular resolution is comparable to focusing mirror for Cu radiation.
10 20 30 40 50 60 70 80 90 100 110 120 130 140
0
10000
40000
90000
160000
Intensity[coutns]
Experimental data
Empty capillary 0.3 mm
2theta [deg]
6000
4000
2000
Intensity[counts]
21.6 21.7 21.8 21.9 22.0 22.1 22.2 22.3 22.4 22.5 22.6
21.9962 (°), 6800.6 (counts)
0.0474 (°)
2theta [deg]
10
5
0
-5
G(r)(Å-2
)
Radial distance [Å]
10 20 30 40 50 60
Gdiff
Gobs
Gcalc
-10
70
10 20 30 40 50 60 70 80 90 100 110 120 130 140
0
10000
40000
90000
Intensity[
2theta [deg]
6000
4000
2000
Intensity[counts]
21.6 21.7 21.8 21.9 22.0 22.1 22.2 22.3 22.4 22.5 22.6
21.9962 (°), 6800.6 (counts)
0.0474 (°)
2theta [deg]
10
5
0
-5
G(r)(Å-2
)
Radial distance [Å]
10 20 30 40 50 60
Gdiff
Gobs
Gcalc
-10
7010 20 30 40 50 60 70 80 90 100 110 120 130 140
0
10000
40000
90000
160000
Intensity[coutns]
Experimental data
Empty capillary 0.3 mm
2theta [deg]
6000
4000
2000
Intensity[counts]
21.6 21.7 21.8 21.9 22.0 22.1 22.2 22.3 22.4 22.5 22.6
21.9962 (°), 6800.6 (counts)
0.0474 (°)
2theta [deg]
10
5
0
-5
G(r)(Å-2
)
Radial distance [Å]
10 20 30 40 50 60
Gdiff
Gobs
Gcalc
-10
70
8. Figure 12. XRD
measurement of
vanadium oxide
xerogel using Mo
radiation. Background
intensity has been
subtracted from the
data.
Figure 13. Reduced
structure function
of vanadium oxide
xerogel
Figure 14. Atomic PDF
of vanadium oxide
xerogel. Experimental
(circles) and calculated
(red line)
Vanadium oxide xerogel
Vanadium oxide xerogel (V2O5 nH2O)
does not form crystals, that can be
analyzed with the use of traditional
crystallographic methods. The
diffraction pattern (see Figure 12) only
shows a combination of Bragg-like
peaks and broad diffuse features. The
reduced structure function is shown in
Figure 13.
The PDF, derived from the measurement
was compared with the PDF obtained
from a structure model described by
Petkov et al. [8]. This model describes
the crystallites consisting of bilayers of
V2O5, made of square pyramidal VO5
units and separated by water molecules.
PDF analysis in Figure 14 shows a good
fit at distances in the intralayer region
(r < 11 Å) and a not so good agreement
in the interlayer region
(r > 11 Å). The same observation by
Petkov et al. [8] was attributed
to the fact that the bilayer slabs
are not perfectly stacked, but are
turbostratically disordered.
Results and
discussion ctd.
-2
2 6 10 14 184 8 12 16 20
0
2
4
6
-5
0 2 4 6 8 10 12 14 16
0
5
10
100
0 20 40 60 80 100 120 140
1000
10000
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å-1
]
G(r)[Å
-2
]
Interatomic distance r [Å-1
]
8
6
4
2
0
-2
-4
0 5 10 15 20
Gtrunc
Gdiff
Gcalc
-2
2 6 10 14 184 8 12 16 20
0
2
4
6
-5
0 2 4 6 8 10 12 14 16
0
5
10
100
0 20 40 60 80 100 120 140
1000
10000
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å
-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å-1
]
G(r)[Å-2
]
Interatomic distance r [Å-1
]
8
6
4
2
0
-2
-4
0 5 10 15 20
Gtrunc
Gdiff
Gcalc
-2
2 6 10 14 184 8 12 16 20
0
2
4
6
-5
0 2 4 6 8 10 12 14 16
0
5
10
100
0 20 40 60 80 100 120 140
1000
10000
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å
-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å-1
]
G(r)[Å
-2
]
Interatomic distance r [Å-1
]
8
6
4
2
0
-2
-4
0 5 10 15 20
Gtrunc
Gdiff
Gcalc
9. Figure 16. Atomic PDF
of fumed silica
Figure 1. Fumed silica
powder prepared in a
glass capillary
Amorphous solids
Fumed silica powder was used as an
example of applying PDF analysis
to amorphous materials. Traditional
structure analysis does not give much
information; only a few ’humps‘ can
be seen in the scan in Figure 15a.
After calculating the reduced structure
function in Figure 15b more structure
can be observed.
PDF analysis of these data helps
to reveal the short range order by
determining average distances between
the nearest neighbouring atoms.
The PDF in Figure 16 shows five clear
peaks that could be determined as first
and second order Si-Si, O-O or Si-O
interatomic distances in silica as given by
Mozzi and Warren [9].
Figure 15b. Reduced
structure function
calculated from the
experimental data
from Figure 15a.
Figure 15a. XRD
measurement of
fumed silica (red
line) and empty glass
capillary (blue line)
performed with Mo
radiation
-2
1
1
2
3 4
5
2 3 4 5 6 7 8
-1
0
1
2
3
4
5
-2
0 2 4 6 8 10 12 14 16
0
2
-1
100
0 20 40 60 80 100 120 140
1000
10000
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å]
-2
1
1
2
3 4
5
2 3 4 5 6 7 8
-1
0
1
2
3
4
5
-2
0 2 4 6 8 10 12 14 16
0
2
-1
100
0 20 40 60 80 100 120 140
1000
10000
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å]
-2
1
1
2
3 4
5
2 3 4 5 6 7 8
-1
0
1
2
3
4
5
-2
0 2 4 6 8 10 12 14 16
0
2
-1
100
0 20 40 60 80 100 120 140
1000
10000
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å]
(a)
(b)
10. Liquids
As in amorphous materials, liquids
do not have a periodic arrangement
of the atoms, and therefore no sharp
diffraction maxima are observed in the
diffractogram. Figure 18a shows the
XRD measurement of tap water as an
example. PDF analysis helps to observe
the average distance betweens atoms.
Calculation of the reduced structure
function from this diffractogram reveals
the structural information, as can be
seen in Figure 18b.
The PDF in Figure 19 shows a relatively
narrow peak for the first O-O distance
(ca. 2.8 Å). The maxima for the second
and third coordination spheres are less
sharp. These results are in accordance
with the synchrotron data reported by
Hura et al. [10].
Figure 19. Atomic PDF
of liquid water
Results and
discussion ctd.
Figure 18b. Reduced
structure function
calculated from the
experimental data
from Figure 17a.
Figure 18a. XRD
measurement of liquid
water (red line) and
empty glass capillary
(blue line) performed
with Mo radiation
-1
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å
-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å]
-3
1
1
2 3
2 3 4 5 6 7 8 9 10
-2
-1
0
1
2
3
4
-2
0 2 4 6 8 10 12 14 16
0
2
4
100
0 20 40 60 80 100 120 140
1000
10000
-1
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å
-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å]
-3
1
1
2 3
2 3 4 5 6 7 8 9 10
-2
-1
0
1
2
3
4
-2
0 2 4 6 8 10 12 14 16
0
2
4
100
0 20 40 60 80 100 120 140
1000
10000
-1
Intensity[arb.units]F(Q)[Å-1
]G(r)[Å
-2
]
2theta [deg]
Scattering vector Q [Å-1
]
Interatomic distance r [Å]
-3
1
1
2 3
2 3 4 5 6 7 8 9 10
-2
-1
0
1
2
3
4
-2
0 2 4 6 8 10 12 14 16
0
2
4
100
0 20 40 60 80 100 120 140
1000
10000
(a)
(b)
Figure 20. Water
sample prepared in a
glass capillary
11. Conclusion
Results of PDF analysis on a range of samples measured on a standard
laboratory XRD system, equipped with an X-ray tube with a silver or
molybdenum anode, were shown. Meaningful results were achieved, that
allowed for comparison with data reported in literature. Empyrean allows
performing experiments with both high-energy X-ray radiation and a wide 2θ
measurement range and this permitted to obtain data with good quality up to
scattering vectors of 17Å-1 (Mo anode) or 22Å-1 (Ag anode). Larger Q-vectors
can be obtained by using X-rays with higher energy at synchrotron facilities
although in practice values higher than 30 A-1 are rarely used.
The flexibility and the accessibility of the Empyrean system make it the ideal
tool for preparation and pre-screening for valuable synchrotron beam time.
References
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4. Klug, H. P. & Alexander, L. E., 1974, X-ray Diffraction Procedures for
Polycrystalline Materials (New York, NY, USA: Wiley).
5. Farrow, C. L., Juhas, P., Liu, J. W., Bryndin, D., Bozin, E. S., Bloch, J.,
Proffen, Th. & Billinge, S. J. L., 2007, J. Phys.: Condens. Matter, 19,
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Acknowledgements
The authors gratefully acknowledge
Prof. V. Petkov, Central Michigan
University, Mt. Pleasant, MI, USA
and Prof. B. Palosz, Institute of High
Pressure Physics, Polish Academy of
Sciences, Warsaw, Poland respec-
tively for providing the vanadium
oxide xerogel and silicon carbide
samples described in this paper.