Skeletal and Lattice Vibrations of Crystals of Dihalogenobis(pyridine)zinc(II)

1974 ◽  
Vol 52 (11) ◽  
pp. 2005-2015 ◽  
Author(s):  
P. T. T. Wong
Keyword(s):  
Single Molecule ◽  
Room Temperature ◽  
Normal Modes ◽  
Low Frequency ◽  
Far Infrared ◽  
Liquid Nitrogen Temperature ◽  
Lattice Vibrations ◽  
Individual Molecule ◽  
Stretching Vibrations ◽  
The Individual

Detailed measurements of the low-frequency Raman spectra of the crystals of [ZnPy2Cl2] and [ZnPy2Br2] at room temperature, where Py is the pyridine molecule, and the far-infrared spectrum of the crystal of [ZnPy2Cl2] at liquid nitrogen temperature have been made. The vibrational frequencies for the single molecule and for the complete crystal of these two complexes have been calculated and compared with the observed spectra, and the distribution of the potential energy of the normal modes has also been calculated to assist the refinement of the calculation and the interpretation of the spectra. Apparently, the skeletal Zn–ligand vibrations of the individual molecule couple with the lattice vibrations in the crystal, except for the normal modes at 326 cm−1 for [ZnPy2Cl2] and at 250 cm−1 for [ZnPy2Br2] which are dominated by the Zn–halogen stretching vibrations. Reasonably good Zn–ligand stretching force constants were obtained. The nature of the coordination bonds of these complexes has been discussed.

Far Infrared Group Frequencies. V. Oximes and Aldoximes

1973 ◽  
Vol 27 (1) ◽  
pp. 22-26 ◽  
Author(s):  
S. M. Craven ◽  
F. F. Bentley ◽  
D. F. Pensenstadler
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectra ◽  
Low Frequency ◽  
Far Infrared ◽  
Torsional Vibrations ◽  
Lattice Vibrations ◽  
Dilute Solutions ◽  
Solid Samples ◽  
Bending Modes ◽  
Bond Stretch

The low frequency infrared spectra from 450 to 75 cm−1 of seven oximes and five aldoximes have been recorded for pure samples and for dilute solutions in cyclohexane. An intense characteristic band is present in the solution spectra at 367 ± 10 cm−1. This characteristic band shifts to 275 ± 10 cm−1 in the spectra of the OD compounds. The 367 ± 10 cm−1 and 275 ± 10 cm−1 bands are assigned to OH and OD torsional vibrations. A comparison of the solution spectra with spectra of the solid samples indicated that the OH … N hydrogen bond stretch of oximes and aldoximes occurs in 300 to 200 cm−1 region. Strong bands also are present in 140 to 100 cm−1 region which are due to OH … N bending modes or perhaps lattice vibrations.

scholarly journals Room temperature excitation spectroscopy of single quantum dots

2011 ◽  
Vol 2 ◽  
pp. 516-524 ◽  
Author(s):  
Christian Blum ◽  
Frank Schleifenbaum ◽  
Martijn Stopel ◽  
Sébastien Peter ◽  
Marcus Sackrow ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Single Molecule ◽  
Room Temperature ◽  
Cdse Nanocrystals ◽  
Photoluminescence Excitation ◽  
Single Quantum ◽  
Excitation Spectra ◽  
Detection Scheme ◽  
Single Quantum Dots ◽  
The Individual

We report a single molecule detection scheme to investigate excitation spectra of single emitters at room temperature. We demonstrate the potential of single emitter photoluminescence excitation spectroscopy by recording excitation spectra of single CdSe nanocrystals over a wide spectral range of 100 nm. The spectra exhibit emission intermittency, characteristic of single emitters. We observe large variations in the spectra close to the band edge, which represent the individual heterogeneity of the observed quantum dots. We also find specific excitation wavelengths for which the single quantum dots analyzed show an increased propensity for a transition to a long-lived dark state. We expect that the additional capability of recording excitation spectra at room temperature from single emitters will enable insights into the photophysics of emitters that so far have remained inaccessible.

Far-Infrared and Raman Spectra of Ammonium Fluoride and Ammonium Fluoride—d4

1970 ◽  
Vol 24 (1) ◽  
pp. 16-20 ◽  
Author(s):  
J. R. Durig ◽  
D. J. Antion
Keyword(s):  
Thin Films ◽  
Raman Spectra ◽  
Infrared Spectra ◽  
Low Frequency ◽  
Far Infrared ◽  
Ammonium Fluoride ◽  
Isotopic Shift ◽  
Lattice Vibrations ◽  
Infrared And Raman Spectra ◽  
Far Infrared Spectra

The far-infrared spectra of thin films of NH4F and ND4F and the Raman spectra of polycrystalline samples of both compounds have been recorded at −170°C. Two low-frequency lattice vibrations were observed in each spectrum and these have been assigned as optical translations on the basis of their isotopic shift factors. Librational modes were not observed in any of the spectra.

Low Frequency Lattice Absorption in RbAg4I5 Solid Electrolyte

1973 ◽  
Vol 28 (6) ◽  
pp. 1042-1043 ◽  
Author(s):  
G. Eckold ◽  
K. Funke
Keyword(s):  
Solid Electrolyte ◽  
Frequency Band ◽  
Low Frequency ◽  
Far Infrared ◽  
High Amplitude ◽  
Lattice Vibrations ◽  
Infrared Transmission

Far infrared transmission and reflexion measurements were performed on polycrystalline samples of α-RbAg4I5 solid electrolyte. As in α-AgI, an anomalous broad low frequency ab­sorption band centred at 5 · 1011 Hz is found in addition to the lattice absorption at ca. 3 · 1012 Hz. Since it is rather tempera­ture insensitive, the low frequency band indicates the exis­tence of very slow high amplitude lattice vibrations in this material.

Infrared Absorption by Granular Metals

1990 ◽  
Vol 195 ◽  
Author(s):  
D.B. Tanner ◽  
Y.H. Kim ◽  
C.L. Carr
Keyword(s):  
Infrared Absorption ◽  
Electric Dipole ◽  
Low Frequency ◽  
Far Infrared ◽  
Percolation Transition ◽  
Metallic Particles ◽  
Tenfold Increase ◽  
Normal Metals ◽  
Theoretical Predictions ◽  
The Individual

ABSTRACTThe infrared properties of granular metals and superconductors are qualitatively in accord with effective medium ideas, with insulating behavior below a percolation transition and metallic response above. An exception is the far-infrared absorption at low metallic concentrations, which is much stronger than theoretical predictions. Measurements of superconductors and of normal metals in different hosts suggest that this absorption is predominately electric dipole rather than the magnetic dipole (eddy current) absorption which is expected to be the dominant low-frequency loss in highly conducting particles. Measurements of clustered and non-clustered samples suggest that the strong far-infrared absorption does not arise from the clustering together of the individual metallic particles, although clustering does lead to about a tenfold increase in absorption.

Far Infrared Characterization of Single and Double Walled Carbon Nanotubes

2011 ◽  
Vol 1284 ◽  
Author(s):  
S. G. Chou ◽  
Z. Ahmed ◽  
G.G. Samsonidze ◽  
J. Kong ◽  
M. S. Dresselhaus ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Room Temperature ◽  
Low Frequency ◽  
Far Infrared ◽  
Diameter Distribution ◽  
Thermal Excitation ◽  
Polyethylene Matrix ◽  
Swcnt Sample ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

ABSTRACTHigh resolution far infrared absorption measurements were carried out for single walled and double walled carbon nanotubes samples (SWCNT and DWCNT) encased in a polyethylene matrix to investigate the temperature and bundling effects on the low frequency phonons associated with the low frequency circumferential vibrations. At a temperature where kBT is significantly lower than the phonon energy, the broad absorption features as observed at room temperature become well resolved phonon transitions. For a DWCNT sample whose inner tubes have a similar diameter distribution as the SWCNT sample studied, a series of sharp features were observed at room temperature at similar positions as for the SWCNT samples studied. The narrow linewidth is attributed to the fact that the inner tubes are isolated from the polyethylene matrix and the weak inter-tubule interactions. More systematic studies will be required to better understand the effects of inhomogeneous broadening and thermal-excitation on the detailed position and lineshape of the low frequency phonon features in carbon nanotubes.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

scholarly journals High-Pressure Spectroscopy Study of Zn(IO3)2 Using Far-Infrared Synchrotron Radiation

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Akun Liang ◽  
Robin Turnbull ◽  
Enrico Bandiello ◽  
Ibraheem Yousef ◽  
Catalin Popescu ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Synchrotron Radiation ◽  
Infrared Radiation ◽  
Room Temperature ◽  
Far Infrared ◽  
Low Pressure ◽  
Pressure Response ◽  
Spectroscopy Study ◽  
Far Infrared Radiation

We report the first high-pressure spectroscopy study on Zn(IO3)2 using synchrotron far-infrared radiation. Spectroscopy was conducted up to pressures of 17 GPa at room temperature. Twenty-five phonons were identified below 600 cm−1 for the initial monoclinic low-pressure polymorph of Zn(IO3)2. The pressure response of the modes with wavenumbers above 150 cm−1 has been characterized, with modes exhibiting non-linear responses and frequency discontinuities that have been proposed to be related to the existence of phase transitions. Analysis of the high-pressure spectra acquired on compression indicates that Zn(IO3)2 undergoes subtle phase transitions around 3 and 8 GPa, followed by a more drastic transition around 13 GPa.

scholarly journals A role for the fusogen eff-1 in epidermal stem cell number robustness in Caenorhabditis elegans

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sneha L. Koneru ◽  
Fu Xiang Quah ◽  
Ritobrata Ghose ◽  
Mark Hintze ◽  
Nicola Gritti ◽  
...  
Keyword(s):  
Stem Cell ◽  
Caenorhabditis Elegans ◽  
Cell Fate ◽  
Single Molecule ◽  
Phenotypic Variability ◽  
Low Frequency ◽  
Time Lapse ◽  
Cell Number ◽  
Seam Cell ◽  
Neuronal Tissues

AbstractDevelopmental patterning in Caenorhabditis elegans is known to proceed in a highly stereotypical manner, which raises the question of how developmental robustness is achieved despite the inevitable stochastic noise. We focus here on a population of epidermal cells, the seam cells, which show stem cell-like behaviour and divide symmetrically and asymmetrically over post-embryonic development to generate epidermal and neuronal tissues. We have conducted a mutagenesis screen to identify mutants that introduce phenotypic variability in the normally invariant seam cell population. We report here that a null mutation in the fusogen eff-1 increases seam cell number variability. Using time-lapse microscopy and single molecule fluorescence hybridisation, we find that seam cell division and differentiation patterns are mostly unperturbed in eff-1 mutants, indicating that cell fusion is uncoupled from the cell differentiation programme. Nevertheless, seam cell losses due to the inappropriate differentiation of both daughter cells following division, as well as seam cell gains through symmetric divisions towards the seam cell fate were observed at low frequency. We show that these stochastic errors likely arise through accumulation of defects interrupting the continuity of the seam and changing seam cell shape, highlighting the role of tissue homeostasis in suppressing phenotypic variability during development.

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