Diode laser study of IR multiphoton-induced depletion of rotational sublevels of the ground vibrational state of SF6 molecules cooled in a pulsed free jet

A pulsed frequency tunable diode laser was used to investigate the IR multiphoton-induced depletion of rotational sublevels of the ground vibrational state of SF₆ molecules cooled in a pulsed free jet at exciting energy densities between ≈10^-2 and 2.3 J cm^-2. The depletion of all rotational sublevels was effective at considerable (≈5–11 cm^-1) pumping frequency detunings from the linear absorption spectrum (LAS) of the molecule the width of which under the conditions of experiment (T_rot ≈ 18 K) was ≈2–3 cm^-1. The fraction of molecules excited by a pumping pulse from individual rotational sublevels was measured and its dependence on the exciting pulse frequency and energy density investigated. The effect of collisions on the depletion of the rotational sublevels was studied.