Knowledge Bank

The $H2O$ absorption lines shifts induced by pressure of noble gases like He, Ne, Ar, Kr, and Xe were investigated in the visible spectral range near 0.7 mm using the dual-channel photoacoustic laser spectrometer with the spectral resolution of $0.01cm-1$. The measurements of the shifts of the vibration-rotation lines of $\nu 1+3\nu 3$ band were made at several buffer gas pressure inside the interval from 100 to 760 torr. The experimental values of shifts coefficients were compared with the theoretical ones. The method of calculations is described in details including the trajectories curvature effect of the colliding molecules. In the case of $H2O$ molecule collisions with He and Ne atoms the best agreement between experimental and theoretical data is observed when the curvature of trajectories of colliding partners is taken into account. The problem of optimal determining of polarizability of $H2O$ molecule in exited vibrational state is also discussed.