Rovibrational jet-cooled spectroscopy of the Kr−H2O van der Waals complex in the ν2 bending mode region of H2O
Résumé
Five rovibrational bands of the Kr−H 2 O complex have been recorded in the ν 2 bending region of H 2 O using a quantum cascade laser coupled to a pulsed slit supersonic jet. Four of them have been unambiguously assigned to the Σ and Π states in v 2 = 1, 1 11 , 1 10 , and 2 12 rotational levels of the monomer based on ground state combination differences and similarities with the vibration-rotation tunneling states of Ar−H 2 O. One of the bands is tentatively assigned to a combination band with two quanta of intermolecular van der Waals stretching mode (ν s). Due to the efficient rovibrational cooling in our pulsed supersonic expansion, all observed bands originate from the lowest lying states. Four of them are from the lowest ortho ground state Σ e (1 01) and one of them is from the lowest para ground state Σ e (0 00). The jet-cooled spectra have been analyzed in terms of a nearly free internal rotor model taking into account Coriolis couplings between close lying Σ and Π levels. Molecular parameters for the five upper vibrational states, band origin, rotational and centrifugal distortion constants have been accurately determined. The β parameter describing the Coriolis coupling between the Σ and Π states originating from the (212) state has also been obtained.
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