scholarly journals Relaxation dynamics of deeply supercooled confined water in l,l-diphenylalanine micro/nanotubes

2015 ◽  
Vol 17 (48) ◽  
pp. 32126-32131 ◽  
Author(s):  
P. M. G. L. Ferreira ◽  
M. S. Ishikawa ◽  
S. Kogikoski ◽  
W. A. Alves ◽  
H. Martinho
Keyword(s):  
Temperature Dependence ◽  
Low Frequency ◽  
Confined Water ◽  
Relaxation Dynamics ◽  
Phonon Modes ◽  
Raman Active Phonon

The temperature dependence (10–290 K) of the low-frequency (20–150 cm−1) Raman-active phonon modes of deeply supercooled confined water in l,l-diphenylalanine micro/nanotubes was analyzed.

Temperature Dependence of the Air/Water Interface Revealed by Polarization Sensitive Sum-Frequency Generation Spectroscopy

2018 ◽  
Author(s):  
Daniel R. Moberg ◽  
Shelby C. Straight ◽  
Francesco Paesani
Keyword(s):  
Temperature Dependence ◽  
Low Frequency ◽  
Potential Energy Function ◽  
Md Simulations ◽  
Sum Frequency Generation ◽  
Water Molecules ◽  
Water Interface ◽  
Sum Frequency ◽  
Air Water Interface ◽  
Frequency Generation

<div> <div> <div> <p>The temperature dependence of the vibrational sum-frequency generation (vSFG) spectra of the the air/water interface is investigated using many-body molecular dynamics (MB-MD) simulations performed with the MB-pol potential energy function. The total vSFG spectra calculated for different polarization combinations are then analyzed in terms of molecular auto-correlation and cross-correlation contributions. To provide molecular-level insights into interfacial hydrogen-bonding topologies, which give rise to specific spectroscopic features, the vSFG spectra are further investigated by separating contributions associated with water molecules donating 0, 1, or 2 hydrogen bonds to neighboring water molecules. This analysis suggests that the low frequency shoulder of the free OH peak which appears at ∼3600 cm−1 is primarily due to intermolecular couplings between both singly and doubly hydrogen-bonded molecules. </p> </div> </div> </div>

scholarly journals Low-frequency optical phonon modes and carrier mobility in the halide perovskite CH3NH3PbBr3 using terahertz time-domain spectroscopy

2017 ◽  
Vol 111 (20) ◽  
pp. 201903 ◽  
Author(s):  
Daming Zhao ◽  
Jonathan M. Skelton ◽  
Hongwei Hu ◽  
Chan La-o-vorakiat ◽  
Jian-Xin Zhu ◽  
...  
Keyword(s):  
Time Domain ◽  
Optical Phonon ◽  
Carrier Mobility ◽  
Low Frequency ◽  
Terahertz Time Domain Spectroscopy ◽  
Phonon Modes ◽  
Time Domain Spectroscopy ◽  
Halide Perovskite

Temperature dependence of the low-frequency surface impedance of metals near the extreme anomalous limit

1978 ◽  
Vol 17 (4) ◽  
pp. 1721-1737 ◽  
Author(s):  
A. Manz ◽  
J. Black ◽  
Kh. Pashaev ◽  
D. L. Mills
Keyword(s):  
Temperature Dependence ◽  
Surface Impedance ◽  
Low Frequency

Temperature dependence of low-frequency optical phonons in TlInS2

2015 ◽  
Vol 12 (6) ◽  
pp. 826-829 ◽  
Author(s):  
Raul Paucar ◽  
YongGu Shim ◽  
Kazuki Wakita ◽  
Oktay Alekperov ◽  
Nazim Mamedov
Keyword(s):  
Temperature Dependence ◽  
Low Frequency ◽  
Optical Phonons

Temperature-Dependence of Zone-Center Phonon Modes in 4H-SiC

2004 ◽  
Vol 457-460 ◽  
pp. 649-652 ◽  
Author(s):  
Caroline Blanc ◽  
Julien Pernot ◽  
Jean Camassel
Keyword(s):  
Temperature Dependence ◽  
Phonon Modes

Interaction of Point Defects in Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 115-122
Author(s):  
J. H. Bilgram ◽  
H. Gränicher
Keyword(s):  
Experimental Data ◽  
Dielectric Properties ◽  
Temperature Dependence ◽  
Point Defects ◽  
Low Frequency ◽  
Defect Concentration ◽  
Dielectric Measurements ◽  
Long Time ◽  
Nmr Techniques ◽  
Bjerrum Defect

AbstractThe interaction of point detects in ice has been neglected for a long time. Experimental data obtained from dielectric measurements on HF-doped crystals stimulated a new evaluation of the possibility of an interaction between Bjerrum defects and ions. In a previous paper it has been shown that this leads us to assume the existence of aggregates of Bjerrum defects and ions. In this paper these aggregates and Bjerrum defects are used to explain the dielectric properties of ice, especially the temperature dependence of the product of the high and low frequency conductivity σ0σ∞.The interaction of Bjerrum defects and impurity molecules leads to a dependence of the concentration of frenkel pairs on Bjerrum-defect concentration. At HF concentrations above the native Bjerrum-defect concentration the formation of a Frenkel pair is enhanced. This leads to the fast out-diffusion which has been studied in highly doped crystals by means of NMR techniques.

Calculation of NQR v's and T1-1' s being proportional to T4 and T5 , respectively

1990 ◽  
Vol 45 (3-4) ◽  
pp. 536-540
Author(s):  
Mariusz Máckowiak ◽  
Costas Dimitropoulos
Keyword(s):  
Temperature Dependence ◽  
Relaxation Rate ◽  
Spin System ◽  
Low Frequency ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Lattice Vibrations ◽  
Spin Lattice ◽  
Simplifying Assumptions ◽  
The One

Abstract The second-order Raman phonon process for a multilevel spin system is shown to give a quadru-polar spin-lattice relaxation rate T1-1varying as T5 at very low temperatures. This relaxation rate for quadrupole spins is similar to the one discussed for a paramagnetic spin system having a multilevel ground state. The temperature dependence of T1 is discussed on the basis of some simplifying assumptions about the nature of the lattice vibrations in the Debye approximation. This type of relaxation process has been observed below 20 K in tetramethylammonium hydrogen bis-trichloroacetate for the 35Cl T1-1 . Below 20 K the NQR frequency in the same crystal reveals a T4 temperature dependence due to the induced modulations of the vibrational and librational coordinates by the low-frequency acoustic phonons.

scholarly journals Continuum limit of the vibrational properties of amorphous solids

2017 ◽  
Vol 114 (46) ◽  
pp. E9767-E9774 ◽  
Author(s):  
Hideyuki Mizuno ◽  
Hayato Shiba ◽  
Atsushi Ikeda
Keyword(s):  
Large Scale ◽  
Continuum Limit ◽  
Scaling Law ◽  
Mean Field ◽  
Low Frequency ◽  
Amorphous Solids ◽  
Mode Analysis ◽  
Vibrational Modes ◽  
Phonon Modes ◽  
The Continuum

The low-frequency vibrational and low-temperature thermal properties of amorphous solids are markedly different from those of crystalline solids. This situation is counterintuitive because all solid materials are expected to behave as a homogeneous elastic body in the continuum limit, in which vibrational modes are phonons that follow the Debye law. A number of phenomenological explanations for this situation have been proposed, which assume elastic heterogeneities, soft localized vibrations, and so on. Microscopic mean-field theories have recently been developed to predict the universal non-Debye scaling law. Considering these theoretical arguments, it is absolutely necessary to directly observe the nature of the low-frequency vibrations of amorphous solids and determine the laws that such vibrations obey. Herein, we perform an extremely large-scale vibrational mode analysis of a model amorphous solid. We find that the scaling law predicted by the mean-field theory is violated at low frequency, and in the continuum limit, the vibrational modes converge to a mixture of phonon modes that follow the Debye law and soft localized modes that follow another universal non-Debye scaling law.

Quantum Dynamics of Exciton Transport and Dissociation in Multichromophoric Systems

2021 ◽  
Vol 72 (1) ◽  
pp. 591-616 ◽  
Author(s):  
Wjatscheslaw Popp ◽  
Dominik Brey ◽  
Robert Binder ◽  
Irene Burghardt
Keyword(s):  
Charge Transfer ◽  
Quantum Dynamics ◽  
Low Frequency ◽  
Functional Materials ◽  
Phonon Modes ◽  
Quantum Dynamical ◽  
Exciton Migration ◽  
Exciton Transport ◽  
Charge Transfer Excitons ◽  
Vibronic Couplings

Due to the subtle interplay of site-to-site electronic couplings, exciton delocalization, nonadiabatic effects, and vibronic couplings, quantum dynamical studies are needed to elucidate the details of ultrafast photoinduced energy and charge transfer events in organic multichromophoric systems. In this vein, we review an approach that combines first-principles parameterized lattice Hamiltonians with accurate quantum dynamical simulations using advanced multiconfigurational methods. Focusing on the elementary transfer steps in organic functional materials, we address coherent exciton migration and creation of charge transfer excitons in homopolymers, notably representative of the poly(3-hexylthiophene) material, as well as exciton dissociation at polymer:fullerene heterojunctions. We emphasize the role of coherent transfer, trapping effects due to high-frequency phonon modes, and thermal activation due to low-frequency soft modes that drive a diffusive dynamics.

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