Study of the H2O dipole moment and polarisability vibrational dependence by the analysis of rovibrational line shifts.

Abstract The study of the H 2 O dipole moment μ and polarisability α vibrational dependence is based on the comparison of experimental and calculated line shifts induced by argon, nitrogen, and air pressure in different H 2 O vibrational bands. Obtained dependence α on the stretching vibrations is in good agreement with the existing ab initio calculations in the literature, but the dependence α on the bending vibration is quite different. To clarify the dependence of μ and α on the bending vibration, the shifts of selected H 2 O lines of the 4ν 2 , 5ν 2 , and 6ν 2 bands induced by argon, hydrogen and helium pressure are measured with the help of a Bruker IFS HR 125 spectrometer at room temperature with a spectral resolution of 0.01 cm−1. The comparison of experimental and calculated results with different values of μ and α line shifts is given. Graphical Abstract Unlabelled Image Highlights • A new vibrational dependence of the H 2 O dipole moment was obtained. • The dipole moment and polarizability of H 2 O molecule from the line shift calculations. • The problem of the ambiguity for the highly excited bending states. [ABSTRACT FROM AUTHOR]