Absorption by water dimers in the water vapor IR spectra at different temperatures
O.B. Rodimova
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: IR water vapor spectrum, continuum absorption, water vapor dimer, longwave approximation
Abstract
Contributions of stable dimers to the water continuum in the 1600 and 8800 cm-1 bands are examined. They are found as the difference between experimental data and the calculation data within the asymptotic line wing theory taking into account the violation of the longwave approximation for the molecular centers of mass. The stable dimer contribution is close in value to the contribution due to all other pair interactions and decreases with increasing temperature. The estimate of the equilibrium constant of the dimer formation reaction is derived proceeding from the temperature dependence of the classical interaction potential of water molecules describing the temperature behavior of the second virial coefficient.
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