Showing papers by "Shri Singh published in 1985"
TL;DR: In this article, a simple theory of the gas-phase far-infrared collision-induced absorption spectra of two molecules with tetrahedral symmetry, methane (CH4) and tetrafluoromethane (CF4), was presented.
Abstract: We present a simple theory of the gas-phase far-infrared collision-induced absorption spectra of two molecules with tetrahedral symmetry, methane (CH4) and tetrafluoromethane (CF4). We assume that in these molecules CIA arises through octopolar and hexadecapolar induction. By neglecting the small anisotropies in the intermolecular CH4-CH4 and CF4-CF4 potentials, we can express the spectral profiles as convolutions of single-molecule free rotation spectra with intermolecular translational components. Information theory is used to estimate the ‘least biased’ form for the latter, based on our knowledge of their spectral moments (the calculation of the zeroth through sixth moments is described in an appendix). In this way we avoid the need to make questionable assumptions about the system dynamics. The computed lineshapes are in excellent agreement with the available experimental data.
14 citations
TL;DR: In this article, a simple theory of the far-infrared collision-induced absorption spectrum of liquid methane is presented, which assumes that CIA arises through octopolar and hexadecapolar induction and uses information theory to estimate the least biased form for the latter, based on their zeroth and second spectral moments.
Abstract: We present a simple theory of the far-infrared collision-induced absorption spectrum of liquid methane. We assume that CIA arises through octopolar and hexadecapolar induction. By neglecting the small anisotropy in the intermolecular potential, we can represent the spectral profile as convolutions of single-molecule free rotation spectra with intermolecular translational components. Information theory is used to estimate the ‘ least biased ’ form for the latter, based on our knowledge of their zeroth and second spectral moments (the calculation of these moments is described in an 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 lineshapes are in excellent agreement with the available experimental data.
10 citations
TL;DR: In this article, a simple theory of the far-infrared collision-induced absorption spectrum of liquid nitrogen is presented, where the spectral profile is represented as convolution of a single-molecule free-rotation spectrum with an intermolecular translational component.
Abstract: 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%.
7 citations
TL;DR: In this paper, the authors apply information theory to the many-body translational problem in liquid tetrafluoromethane collision-induced absorption, which uses as input only spectral moments.
3 citations