This document summarizes a study on the size-reduction effect on the photophysical properties of nano-crystals of [Ru(bpy)3][NaCr(ox)3] and the functionalization of their surface. Key points include:
1) Nano-crystals of various sizes from 140nm to 2.5μm were synthesized using a reverse micelle technique to control size. Smaller nano-crystals showed faster energy transfer from core to surface and shorter luminescence decay times.
2) Fluorescence line narrowing spectroscopy showed the crystalline environment at the surface is slightly different than the bulk. Time-resolved spectra indicate directional energy transfer from core to surface.
3)
Plenary lecture of the XIV SBPMat Meeting, given by Prof. Nader Engheta (University of Pennsylvania) on September 28, 2015, in Rio de Janeiro (Brazil).
Plenary lecture of the XIV SBPMat Meeting, given by Prof. Nader Engheta (University of Pennsylvania) on September 28, 2015, in Rio de Janeiro (Brazil).
Electron Diffusion and Phonon Drag Thermopower in Silicon NanowiresAI Publications
The field of thermoelectric research has undergone a renaissance and boom in the fast two decades, largely fueled by the prospect of engineering electronic and phononic properties in nanostructures, among which semiconductor nanowires (NWs) have served both as an important platform to investigate fundamental thermoelectric transport phenomena and as a promising route for high thermoelectric performance for device applications. In this report we theoretical studied the carrier diffusion and phonon-drag contribution to thermoelectric performance of silicon nanowires and compared with the existing experimental data. We observed a good agreement between theoretical data and experimental observations in the overall temperature range from 50 – 350 K. Electron diffusion thermopower is found to be dominant mechanism in the low temperature range and shows linear dependence with temperature.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
NANO281 is the University of California San Diego NanoEngineering Department's first course on the application of data science in materials science. It is taught by Professor Shyue Ping Ong of the Materials Virtual Lab (http://www.materialsvirtuallab.org).
Los días 22 y 23 de junio de 2016 organizamos en la Fundación Ramón Areces un simposio internacional sobre 'Materiales bidimensionales: explorando los límites de la física y la ingeniería'. En colaboración con el Massachusetts Institute of Technology (MIT), científicos de este prestigioso centro de investigación mostraron las propiedades únicas de materiales como el grafeno, de solo un átomo de espesor, y al mismo tiempo más resistente que el acero y mucho más ligero.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
A thirty-four billion solar mass black hole in SMSS J2157–3602, the most lumi...Sérgio Sacani
From near-infrared spectroscopic measurements of the Mg II emission line doublet, we estimate the black hole (BH) mass of the quasar, SMSS J215728.21–360215.1, as being (3.4 ± 0.6) × 1010 M⊙ and refine the redshift of the quasar to be z = 4.692. SMSS J2157 is the most luminous known quasar, with a 3000 Å luminosity of (4.7 ± 0.5) × 1047 erg s−1 and an estimated bolometric luminosity of 1.6 × 1048 erg s−1 , yet its Eddington ratio is only ∼0.4. Thus, the high luminosity of this quasar is a consequence of its extremely large BH – one of the most massive BHs at z > 4.
An alternative way to calculate spin ground state of organometallic complexes. Shown for more than one metallic centers and complex formalism, For more please feel free to mail me.
If you are looking for an effective & secure way to find the best driving instructor, Visit our website. We can help you to find an approved instructor.
Electron Diffusion and Phonon Drag Thermopower in Silicon NanowiresAI Publications
The field of thermoelectric research has undergone a renaissance and boom in the fast two decades, largely fueled by the prospect of engineering electronic and phononic properties in nanostructures, among which semiconductor nanowires (NWs) have served both as an important platform to investigate fundamental thermoelectric transport phenomena and as a promising route for high thermoelectric performance for device applications. In this report we theoretical studied the carrier diffusion and phonon-drag contribution to thermoelectric performance of silicon nanowires and compared with the existing experimental data. We observed a good agreement between theoretical data and experimental observations in the overall temperature range from 50 – 350 K. Electron diffusion thermopower is found to be dominant mechanism in the low temperature range and shows linear dependence with temperature.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
NANO281 is the University of California San Diego NanoEngineering Department's first course on the application of data science in materials science. It is taught by Professor Shyue Ping Ong of the Materials Virtual Lab (http://www.materialsvirtuallab.org).
Los días 22 y 23 de junio de 2016 organizamos en la Fundación Ramón Areces un simposio internacional sobre 'Materiales bidimensionales: explorando los límites de la física y la ingeniería'. En colaboración con el Massachusetts Institute of Technology (MIT), científicos de este prestigioso centro de investigación mostraron las propiedades únicas de materiales como el grafeno, de solo un átomo de espesor, y al mismo tiempo más resistente que el acero y mucho más ligero.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
A thirty-four billion solar mass black hole in SMSS J2157–3602, the most lumi...Sérgio Sacani
From near-infrared spectroscopic measurements of the Mg II emission line doublet, we estimate the black hole (BH) mass of the quasar, SMSS J215728.21–360215.1, as being (3.4 ± 0.6) × 1010 M⊙ and refine the redshift of the quasar to be z = 4.692. SMSS J2157 is the most luminous known quasar, with a 3000 Å luminosity of (4.7 ± 0.5) × 1047 erg s−1 and an estimated bolometric luminosity of 1.6 × 1048 erg s−1 , yet its Eddington ratio is only ∼0.4. Thus, the high luminosity of this quasar is a consequence of its extremely large BH – one of the most massive BHs at z > 4.
An alternative way to calculate spin ground state of organometallic complexes. Shown for more than one metallic centers and complex formalism, For more please feel free to mail me.
If you are looking for an effective & secure way to find the best driving instructor, Visit our website. We can help you to find an approved instructor.
I gave 1 hour seminar at ANSTO (Australian Nuclear Science and Technology Organization) to introduce my approach to magnetism. I see myself as an experimental physicist who is studying magnetism by using neutron scattering techniques. Throughout my career, I had learned local structure analysis (PDF), magnetic structural analysis, and inelastic neutron scattering technique to investigate superconductor, multiferroics, antiferromagnets, helimagnets, and frustrated magnets. I was trying to explain my approach to magnetism as an experiment physicist to both professional scientists and novices.
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Presentation given at the workshop "High-Resolution Submillimeter Spectroscopy of the Interstellar Medium and Star Forming Regions — From Herschel to ALMA and Beyond" held in Zakopane, Poland, May 2015: https://fox.ncac.torun.pl/export/herschel2alma/?slcn=main
It describes how different properties of materials changes when reduced to nano. Property includes electrical, optical, mechanical, magnetic, thermal etc.
How Carbon Nanotubes Collapse on Different Ag Surface?ijrap
The collapse and stability of carbon nanotubes (CNTs) on noble metal silver different surfaces were studied
using molecular mechanics and molecular dynamics simulations. From the results, it can be seen that the
CNTs can collapse spontaneously onto different silver surface [(1 0 0), (1 1 0), (1 1 1)] due to the van der
Waals force between them. Furthermore, the CNT collapsing on (1 0 0) and (1 1 1) surface are much easier
than that on (1 1 0) surface. Moreover, the results show that the collapsed CNTs exhibit as linked graphene
ribbons and have the largest area to contact with the Ag surface, which greatly enhances adhesion between
the CNTs and the Ag surface and keeps the system much more stable.
How Carbon Nanotubes Collapse on Different Ag Surface? ijrap
The collapse and stability of carbon nanotubes (CNTs) on noble metal silver different surfaces were studied
using molecular mechanics and molecular dynamics simulations. From the results, it can be seen that the
CNTs can collapse spontaneously onto different silver surface [(1 0 0), (1 1 0), (1 1 1)] due to the van der
Waals force between them. Furthermore, the CNT collapsing on (1 0 0) and (1 1 1) surface are much easier
than that on (1 1 0) surface. Moreover, the results show that the collapsed CNTs exhibit as linked graphene
ribbons and have the largest area to contact with the Ag surface, which greatly enhances adhesion between
the CNTs and the Ag surface and keeps the system much more stable.
X-raydiffraction has a very significant role in crystal determination.. specially in the field of Pharmaceutical analysis.
It contains the requirement for M.pharm 1st year according to RGUHS syllabus.
1. Study of the Size-Reduction Effect on the
Photophysical Properties of [Ru(bpy)3][NaCr(ox)3]
Nano-Crystals and Functionalization of their Surface
Elia Previtera
November 24, 2016
Département de Chimie Physique, Université de Genève
Hauser Group
4. Nano-Size Materials
At least one dimensions between 1 and 100 nm
X
At least one physical or chemical size-
dependent property
M.L. Grieneisen, M. Zhang, Small 2011, 7, No. 20, 2836-2839.
What is What in the Nanoworld: A Handbook on Nanoscience and Nanotechnology
2012.
3
5. Energy Transfer and Migration
..
... .
..
Homo-Energy Transfer or Energy Migration
Hetero-Energy Transfer
..
..
. .
. .
..
. .
.
. .
.
..
... .
..
4
7. Non-radiative Energy Transfer and Migration
HOMO
LUMO
Förster
AcceptorDonor*
Dexter
AcceptorDonor*
kEET
F
∝
1
RDA
⎛
⎝
⎜⎜
⎞
⎠
⎟⎟
6
kEET
Ex
∝exp −
2RDA
RDA
0
⎛
⎝
⎜⎜
⎞
⎠
⎟⎟
HOMO
LUMO
10 Å < Rc
F < 80 Å 1 Å < Rc
Ex < 10 Å
6
8. Non-radiative Energy Transfer and Migration
ΩDA
= gD
(E)gA
(E)dE∫
Spectral overlap integral
ΩDA
λ
Emi(A)Emi(D)Abs(D) Abs(A)
I
gD gA
7
9. Energy Transfer and Migration in Natural Antennae
6 CO2 + 6 H2O C6H12O6 + 6 O2
Respiration
Photosynthesis
Sunlight Energy stored
Energy storedEnergy released
Nature, 1995, 374, 517. 8
10. Energy Transfer and Migration in Natural Antennae
Photosynthetic unit of Rhodopseudomonas acidophila
Nature, 1995, 374, 517. 9
11. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3]
Anionic Chiral 3D Polymeric Oxalate Networks
[NaCr(ox)3][Ru(bpy)3]
Na++
D3
[Cr(ox)3]3-
Crystal system
Cubic
Z = 4
Chiral Spacegroup
P213
Site symmetry of
all metal ions
C3
S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 10
12. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3]
Anionic Chiral 3D Polymeric Oxalate Networks
[NaCr(ox)3][Ru(bpy)3]
Na++
D3
[Cr(ox)3]3-
Crystal system
Cubic
Z = 4
Chiral Spacegroup
P213
Site symmetry of
all metal ions
C3
S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 11
13. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3]
Anionic Chiral 3D Polymeric Oxalate Networks
[NaCr(ox)3][Ru(bpy)3]
Na++
D3
[Cr(ox)3]3-
Crystal system
Cubic
Z = 4
Chiral Spacegroup
P213
Site symmetry of
all metal ions
C3
S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 12
14. 3D oxalate network: [Ru(bpy)3][NaCr(ox)3]
[Ru(bpy)3]2+: antenna
Oxalate Networks to Study Photo-Induced Energy Transfer
Bulk: efficient energy migration in the 2E state of Cr(III)
[NaCr(ox)3]2- network: energy migration
Is there any influence of the crystal size on the energy migration
within the 2E state of the [Cr(ox)3]3- chromophores?
hν
Energy Transfer
Milos. M. et al., Coor. Chem. Rev., 252, 2000, 2540 13
15. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3]
Tetrahedral microcrystalline particles with side length 4 µm
S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521.
5 µm
14
16. How to Synthesize Nanocrystals?
Ø Synthesis by the Reverse Micelles technique
Aqueous phase: Solubilization of
[Ru(bpy)3]Cl2
.6H2O and K3[Cr(ox)3].3H2O
Surfactant: Sodium bis(2-ethylhexyl)
Sulfosuccinate (AOT)
Solvent: n-Heptane
TEM à Tetrahedral Shape of Nanocrystals
Centrifugation and
washing in EtOH
15
17. Size Controlled Micro- and Nanocrystals
Tetrahedral Shape of Nanoparticles
ImageJ
Large Size Distribution
16
1000 nm
18. Size & Volume Weighted Distribution
Iluminescence ≈ a3
a
17Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
< Size > =
Σa
Number of NPs < Size Signal > =
Σ(a x a3)
Total a3
19. Size Controlled Micro- and Nano-crystals
Ø Modification of the water-to-surfactant ratio (Wo)
Wo =
[H2O]
[Surfactant]
Size Control of final product!
Wo= 2 Wo= 5 Wo= 8
2.5 µm MPs changing Wo and lowering the
concentration of reactants inside micelles
(Wo= 8 and 0.025 M)
Previtera E. et al., Adv. Mater. 2015, 27, 1832. 18
21. Chromium (III): d3 in C3 Symmetry
Ligand field states
4A2(t2g
3)
4T2(t2g
2eg
1)
4A2
2E
Oh C3 + Hso
R1 R2
D (2E) = 13.7 cm-1
D (4A2) = 1.3 cm-1
hν hν
Spin-flip
Δr ≈ 0
t2g → eg
Δr ≈ 0.1 Å2E(t2g
3)
ISC
t2g
eg
t2g
eg
t2g
eg
E
RCr-O
Ms = ± 3/2
Ms = ± 1/2
20
22. Solid State Spectroscopy Background
Homogeneous line width and inhomogeneous band broadening
Lorentzian with the
homogeneous linewidth
Γhom
2E
4A2
R1
D
A perfect crystal
Electronic origin of Chromium (III)
Andreas Hauser, Lecture Notes. 21
23. Solid State Spectroscopy Background
Homogeneous line width and inhomogeneous band broadening
Lorentzian with the
homogeneous linewidth
Γhom
2E
4A2
R1
D
A perfect crystalA real crystal
Electronic origin of Chromium (III)
Gaussian profile with the
i n h o m o g e n e o u s b a n d
broadening
Γinh
Andreas Hauser, Lecture Notes. 22
24. Excitation Spectra of Cr3+ R-Lines
Previtera E. et al., Adv. Mater. 2015, 27, 1832. 23
25. Excitation Spectra of Cr3+ R-Lines
Previtera E. et al., Adv. Mater. 2015, 27, 1832. 24
27. Solid State Spectroscopy Background
Laser selective
excitation
non-resonant
fluorescence
2E
4A2
R1
D
resonant fluorescence
In the absence of any other
processes only the excited subset
emits.
The principle of Fluorescence Line Narrowing Spectroscopy (FLN)
Andreas Hauser, Lecture Notes. 26
29. FLN Spectra
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
Ø Energy Transfer Core à Surface
28
30. FLN Spectra across the R1 Absorption
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
Size: 140 nm
Ø Smaller numbers of members in the FLN multiline pattern at lower energy
29
31. FLN Spectra across the R1 Absorption
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
Size: 670 nm Size: 2.5 µm
Ø Smaller numbers of members in the FLN multiline pattern at lower energy
30
32. ZFS as Function of FLN Excitation Wavelength
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
Ø Crystalline environment of the [Cr(ox)3]3- chromophores at the
surface is slightly different to that of the complexes in the bulk
31
33. Time Resolved FLN Spectra
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
hν’
Energy migration inside 2E of Cr(III)
Cr3+
2E
4A2
hν
4A2
2E
Cr3+ Cr3+ Cr3+
4T2
Core Surface
32
34. Luminescence Decay Kinetics
Ø Directional Energy Transfer from the Core to the Surface
Previtera E. et al., Adv. Mater. 2015, 27, 1832.
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
Multi line pattern
decay
(at 14394 cm-1)
τ4 µm = 1.3 ms
τ2.5 µm = 155 µs
τ670 nm = 132 µs
τ140 nm = 57 µs
Broad band rise to
maximum intensity
(at 14371 cm-1)
220 µs for 2.5 mm
180 µs for 670 nm
60 µs for 140 nm
Broad band rise to
maximum intensity
(at 14351 cm-1)
400 µs for 2.5 mm
360 µs for 670 nm
180 µs for 140 nm
33
l
35. How far does the energy travel?
Ø Average distance travelled by the energy is of the order of a few hundreds nm
RC resonant process à up to 30 Å
Ø l = 140 nm à d = 30 nm
10 steps for energy migration
Core à Surface
Ø l = 670 nm à d = 138 nm
46 steps for energy migration
Core à Surface
Ø l = 2.5 µm à d = 510 nm
170 steps for energy migration
Core à Surface
Previtera E. et al., Adv. Mater. 2015, 27, 1832.
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
34
37. Conclusions
• Size-controlled micro- and nano-crystals of [Ru(bpy)3][NaCr(ox)3]
• Directional Energy Transfer from the Core to the Surface
• Average distance travelled by the energy is of the order of few hundreds nm
Previtera E. et al., Adv. Mater. 2015, 27, 1832.
Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979
36
l
38. Control of the surface state
$ Growth of oxalate network shell with
cavities filled with energy acceptor
[Cr(bpy)3]3+
$ Direct chemical grafting of Ln3+ complexes
(Ln3+ = Er3+, Eu3+, Yb3+)
37
46. Conclusions
• It is possible to grow an Oxalate network shell of good crystalline quality
containing in its cavities the energy acceptor [Cr(bpy)3]3+.
• No evidence of energy transfer towards the shell in RuCr@CrCr was found.
45
47. Direct chemical grafting of Ln3+ complexes
Up-Conversion Nanoparticles
Nature Materials 2011. 46
48. Direct chemical grafting of Ln3+ complexes
365 nm
a) b)
[Rh(bpy)3][NaAl(ox)3]ClO4 + [Eu(hfac)3dig] [Rh(bpy)3][NaAl(ox)3]ClO4@[Eu(hfac)3] + dig
Preliminary Test
47
hfac = hexafluoroacetylacetonate
dig = diglyme or bis(2-methoxyethyl)ether
49. Direct chemical grafting of Ln3+ complexes
[Rh(bpy)3][NaAl(ox)3]ClO4 + [Eu(hfac)3dig] [Rh(bpy)3][NaAl(ox)3]ClO4@[Eu(hfac)3] + dig
48
50. Direct chemical grafting of Ln3+ complexes
Reactants Size
nm
[Ru(bpy)3][NaCr(ox)3]
RuCr
220
[Eu(hfac)3dig]
Eu
-
[Er(hfac)3dig]
Er
-
[Yb(hfac)3dig]
Yb
-
RuCr + [Ln(hfac)3dig] RuCr@[Ln(hfac)3] + dig
49
hfac = hexafluoroacetylacetonate
dig = diglyme or bis(2-methoxyethyl)ether
58. • Improving of the NPs’ surface.
• Quenching of the broad band luminescence.
• Efficient excitation energy transfer from the 2E excited states of
the [Cr(ox)3]3- ions located at the surface towards the
lanthanides complexes grafted at the NPs’ surface.
• Good indication of down conversion luminescence related to
the lanthanides transitions 4I9/2à4I15/2 and 2F5/2à2F7/2 for
Erbium and Ytterbium.
• No up-conversion luminescence.
Conclusions
57
59. Outlook
• Direct chemical grafting of [Gd(hfac)3dig]
6P3/2
5/2
7/2
8S7/2
32200cm-1
• Enhancing of the lifetime of the surface [Cr(ox)3]3- chromophores?
• Would direct excitation of [Gd(hfac)3] complexes grafted at the surface give
directional energy transfer towards the chromophores located at the surface or
further into the core? 58
60. • This work contributes to the expansion of the basic
knowledge about nano-size materials.
• The energy can travel few hundreds of nanometers in
NCs. This important basic knowledge can be useful for
future applications in solar energy harvesting and
conversion.
• This work demonstrates that also particles with sizes
bigger than 100 nm can show size-dependent properties.
General Conclusions
59
61. Acknowledgements
Prof. Hauser
Dr. Lawson Daku
Dr. Chakraborty
Dr. Suffren
Dr. Sun
Teresa Delgado Perez
Andrea Missana
Catherine Ludy
Nahid Jeddi
Patrick Barman
Dominique Lovy
Laurent Devenoge
Hauser’ Group:
Prof. Decurtins
Prof. Hagemann
Dr. Tissot
Jury members:
Dr. Moury
Dr. Olchowka
Dr. Bierwagen
Manish Sharma
Daniel Sethio
Angelina Gigante
Hagemann’ Group:
Prof. Piguet
Dr. Nozary
Piguet’ Group:
Dr. Varnholt
Dr. Lawson Daku
Dr. Chakraborty
Dr. Moury
Andrea Missana
Manish Sharma
Corrections:
60