Pair potentials and polarizabilities of LiBr, NaBr, KBr and Br22− have been computed over a range of internuclear separations R using the gaussian orbital SCF-MO method. Together with results previously reported for all other ion pairs, the present values form a complete and consistent set of energy and polarizability data on the bromides of lithium, sodium and potassium.
Infrared fluorescence and double infrared resonance have been used to measure the V-T relaxation of CD3F and CD4 in mixtures with He, Ne, Ar, Kr, Xe and HCl in the gas phase and in the liquid Ar, Kr, Xe. It is shown that the temperature dependence of V-T probabilities in the interval 350–150°K can be attributed to an increasing influence of long range forces. In the mixture CD3F + HCl, where H-bonded complexes CD3F…HCl have been formed, the vibrational relaxation rate considerably increases with decreasing temperature. It is found that the probabilities of V-T energy transfer in cryogenic solutions are lower than those measured in the gas phae.
The “spectral density” I(ω) computed for the Cole Davidson model of dielectric dispersion reveals the asymetric distribution of molecular relaxation times. The linearity between the expression ωI(ω) and the dielectric absorption ε″ does not appear. This experimental study for the primary amines (propylamine to dodecylamine) is in good agreement with the introduced theory.
A molecular dynamics simulation of liquid CH2Cl2 is compared with the far infrared spectrum at the same state point (293K, 1 bar). Two representations of the force field are used, a 3×3 and 5×5 site-site interaction consisting of Lennard-Jones and charge terms. The far infra-red spectrum shows unambiguously that the 5×5 representation is more realistic in the sense that it reproduces the observed spectrum more closely.
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