Far-infrared absorption in liquid nitrogen: a theoretical study

1985 ◽  
Vol 63 (1) ◽  
pp. 76-83 ◽  
Author(s):  
C. G. Joslin ◽  
S. Singh ◽  
C. G. Gray
Keyword(s):  
Liquid Nitrogen ◽  
Single Molecule ◽  
Theoretical Study ◽  
Far Infrared ◽  
Intermolecular Potential ◽  
Line Shapes ◽  
Absolute Intensities ◽  
Induction Mechanism ◽  
Rotation Spectrum ◽  
Small Anisotropy

We present a simple theory of the far-infrared collision-induced absorption spectrum of liquid nitrogen. Assuming a quadrupolar induction mechanism, and neglecting the small anisotropy in the N2 intermolecular potential, we represent the spectral profile as the convolution of a single-molecule free-rotation spectrum with an intermolecular translational component. Information theory is used to estimate the least-biased form for the latter, based on our knowledge of its zeroth and second spectral moments (the calculation of M0tr and M2tr is illustrated in the Appendix). In this way we avoid the need to make questionable assumptions about the system dynamics. Our theory contains no adjustable parameters, yet the computed line shapes are in excellent agreement with the available experimental data. Absolute intensities are underestimated by about 40%.

Collision-induced absorption in the fundamental band of nitrogen gas

1987 ◽  
Vol 65 (12) ◽  
pp. 1629-1635 ◽  
Author(s):  
C. G. Joslin
Keyword(s):  
Single Molecule ◽  
Intermolecular Potential ◽  
Substantial Contribution ◽  
Spectral Profile ◽  
Nitrogen Gas ◽  
Spectral Moments ◽  
Anisotropic Component ◽  
Vibration Rotation ◽  
Small Anisotropy ◽  
Good Agreement

Compressed nitrogen gas absorbs weakly in the vicinity of its vibrational fundamental frequency (ωvib = 2330 cm−1), with an intensity proportional to the square of the density. This absorption arises through vibrational modulation of the quadrupole-induced collisional dipole moment of a pair of N2 molecules. By neglecting the small anisotropy in the N2 intermolecular potential, we represent the spectral profile as the convolution of a single-molecule vibration–rotation band with a two-molecule translational component. Information theory is used to estimate the "least biased" form for the latter, based on our knowledge of its first four nonvanishing spectral moments. Our theory contains no adjustable parameters, yet yields results in good agreement with experiment. Our analysis shows that the anisotropic component of the molecular polarizability makes a fairly substantial contribution, about 12%, to the spectral intensity.

A Theoretical Study of Nonlinear Multi-Channel Graphene Components for the Near and Far-Infrared

2020 ◽  
Author(s):  
Thomas Christopoulos ◽  
Odysseas Tsilipakos ◽  
Vasileios G. Ataloglou ◽  
Emmanouil E. Kriezis
Keyword(s):  
Theoretical Study ◽  
Far Infrared

scholarly journals Experimental and theoretical study of Aspartic acid

2019 ◽  
Keyword(s):  
Aspartic Acid ◽  
Single Molecule ◽  
Dft Calculation ◽  
Theoretical Study ◽  
Quantum Mechanical ◽  
Experimental Ir ◽  
Vibrational Bands ◽  
Computational Research ◽  
Ir And Raman ◽  
Dielectric Environment

The aim of this research is to detect zwittterionic structure of the aspartic acid and confirm the experimental spectra with quantum chemical calculations. The experimental IR and Raman spectra of aspartic acid powder show no vibrational bands of OH and NH stretching in expected spectral region. We assume that zwitterionic structure of aspartic acid is responsible for lowering the frequencies of these vibrations. An extensive experimental and computational research supports this assumption. Our DFT calculation strongly suggests the need for the dielectric environment in order to stabilize the zwitterionic structure of a single molecule. The network of intermolecular hydrogen bonding between aspartic acid molecules provides this dielectric environment. The DFT quantum mechanical calculations corroborate this assumption by optimizing a four-member group of molecules, which also gives an explanation of broad IR spectrum lines.

Far infrared spectroscopy and empirical intermolecular potential for α‐ and γ‐N2 under pressure

1981 ◽  
Vol 74 (5) ◽  
pp. 2675-2685 ◽  
Author(s):  
F. Fondère ◽  
J. Obriot ◽  
Ph. Marteau ◽  
M. Allavena ◽  
H. Chakroun
Keyword(s):  
Infrared Spectroscopy ◽  
Far Infrared ◽  
Intermolecular Potential ◽  
Far Infrared Spectroscopy

Theoretical Study of Far-Infrared Spectra of Some Palladium and Platinum Halide Complexes

2002 ◽  
Vol 106 (15) ◽  
pp. 3819-3822 ◽  
Author(s):  
Lin Zhang ◽  
Hua Wei ◽  
Yu Zhang ◽  
Zijian Guo ◽  
Longgen Zhu
Keyword(s):  
Infrared Spectra ◽  
Theoretical Study ◽  
Far Infrared ◽  
Halide Complexes ◽  
Far Infrared Spectra

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.

Physical Analysis of Structural Transformation in Ge-Incorporated a-SbxSe100-x System

2011 ◽  
Vol 316-317 ◽  
pp. 45-53 ◽  
Author(s):  
Sunanda Sharda ◽  
Neha Sharma ◽  
Pankaj Sharma ◽  
Vineet Sharma
Keyword(s):  
Structural Transformation ◽  
Chalcogenide Glasses ◽  
Theoretical Study ◽  
Far Infrared ◽  
Structural Transformations ◽  
Physical Parameters ◽  
Physical Analysis ◽  
Melt Quenching ◽  
Structural Environment ◽  
Rigidity Percolation

Chalcogenide glasses are suitable for far-infrared and imaging applications. In the present study, Sb10Se90-xGex (x=0, 19, 21, 23, 25, 27) system has been chosen to study structural transformations via physical parameters. Bulk samples with x = 0, 19, 21, 23, 25 and 27 have been prepared using the melt-quenching technique. A theoretical study of the ternary glass system revealed that there was a significant change in the structural environment of the system due to rigidity percolation, which took place as Se was replaced by Ge, and hence resulted in changes in other physical parameters of the system.

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