“…The following values were obtained : U++ = 182.5 cm-1, and U-* = 74.5 cm-1. These values are in good agreement with those obtained by Datta andBarrow (1965, 1968) using a grating instrument, namely vmax=122 cm-1, v++=180 cm-1 and v-+=78 cm-1 for hydrogen chloride in cyclohexane at 35 "C.…”
Equations of rotational motion for rigid linear and symmetrical-top molecules which rotate without any interaction with the surrounding molecules are solved to obtain the dipole correlation function and the imaginary part of the complex permittivity of a non-interacting ensemble of such molecules. The calculated values of the absorption coefficients are compared with the experimental values obtained from far-infrared spectra of hydrogen chloride (a linear molecule) dissolved in various inert solvents, and of ammonia (a symmetrical-top molecule) dissolved in sulphur hexafluoride. For these comparisons, the far-infrared spectrum of hydrogen chloride dissolved in cyclohexane at 25 degrees C was measured, and other spectra were taken from the literature. The theoretically derived spectra were calculated using only reported values of moments of inertia.
“…The following values were obtained : U++ = 182.5 cm-1, and U-* = 74.5 cm-1. These values are in good agreement with those obtained by Datta andBarrow (1965, 1968) using a grating instrument, namely vmax=122 cm-1, v++=180 cm-1 and v-+=78 cm-1 for hydrogen chloride in cyclohexane at 35 "C.…”
Equations of rotational motion for rigid linear and symmetrical-top molecules which rotate without any interaction with the surrounding molecules are solved to obtain the dipole correlation function and the imaginary part of the complex permittivity of a non-interacting ensemble of such molecules. The calculated values of the absorption coefficients are compared with the experimental values obtained from far-infrared spectra of hydrogen chloride (a linear molecule) dissolved in various inert solvents, and of ammonia (a symmetrical-top molecule) dissolved in sulphur hexafluoride. For these comparisons, the far-infrared spectrum of hydrogen chloride dissolved in cyclohexane at 25 degrees C was measured, and other spectra were taken from the literature. The theoretically derived spectra were calculated using only reported values of moments of inertia.
“…The spacing between successive transitions is 20.8 cm -1 as indicated by the arrow in Figure a, which is twice the rotational B constant for the diatom HCl. The 40−280 cm -1 region of this spectrum has been measured previously. , 3 (a) The frequency dependent absorbance spectrum for gaseous HCl. The filled circles denote data acquired with the THz spectrometer and the open circles with the FTIR spectrometer.…”
A combination of pulsed THz transmission and FTIR spectroscopy was employed to measure the normalized frequency dependent absorption coefficient of HCl in spherical, dipolar, and linear solvents (CCl 4 , CHCl 3 , and alkanes, respectively) in the 0-350 cm -1 portion of the far-infrared spectral region. The analysis applied to the measured spectra describes the interaction between the quantum mechanical rigid rotator motion of HCl and the solvent through explicit consideration of the anisotropic potential between HCl and the bath. Nominally, the theory requires two adjustable parameters to fit the solvated HCl absorbance spectra. However, a compilation of experimental results for HCl dissolved in various solvents of high symmetry reveals a quadratic dependence of one parameter, the mean square field of the bath, on solvent polarizability. It is shown that dipole-induced dipole (DID) interactions account for the observed quadratic form. This observation introduces a constraint that reduces the number of adjustable parameters so that unique values for the second fitting parameter, the exponential decay rate of the anisotropic potential time correlation function, may be extracted from the measured absorbance curves. The analysis of HCl-alkane solution spectra reveals a more subtle aspect of this dependence. Only a very weak polarizability dependence was found for solvents of large aspect ratio such as the alkanes. This difference indicates that the molecular polarizability density, not simply the molecular polarizability, dictates the strength of the solvent mean square field. Last, a simple scheme for classifying nonpolar solvents based on DID interactions between the solute and the bath is established.
“…? < 100 cm-' for HCI in cyclohexane [3]. The purpose is that for sufficiently slow perturbations the molecular system can be considered as quasi-isolated and, therefore, we will be able to apply the results of Sect.…”
Section: Some Theoretical Consequences From Generalized Fdtmentioning
confidence: 99%
“…This effect seems to be systematic by nature. Especially we will consider the case of hydrogen and deuterium halides [3], and attempt to interprete that blue-shift with the aid of the very principles of quantum statistics, i.e. without using "models".…”
The physical principles concerning the far-infrared absorption process in liquids are discussed. It is shown that the adiabatic approximation cannot be justified in this physical context. The basic ideas of the Kubo-van Wet linear response theory are discussed in connection with the FIR-absorption process. As an application, the blue-shift of FIR-absorption bands of dipolar molecules due to the transition gaslsolution is interpreted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
