Stimulated emission pumping of intermolecular vibrations in OH–Ar(X 2Π)

Abstract

Stimulated emission spectroscopy has been used to access the intermolecular bending and stretching vibrations supported by the OH(X ²Π)+Ar(¹S₀) potential‐energy surfaces. Manifolds of OH–Ar bending levels, correlating with the j= (3)/(2) , (5)/(2) , and (7)/(2) rotational levels of OH(²Π_3/2), have been observed with zero to three quanta of intermolecular stretch. OH–Ar complexes have also been prepared in intermolecular vibrational levels of the spin–orbit excited state correlating with OH(²Π_1/2). The first dissociation limit, producing OH(²Π_3/2) v=0, j= (3)/(2) +Ar(¹S₀) fragments, has been determined to lie between 93 and 103 cm⁻¹ above the zero‐point level. Complexes prepared in metastable levels, detected up to 200 cm⁻¹ beyond the first dissociation limit, undergo predissociation by using OH rotational or spin–orbit excitation to break the OH–Ar intermolecular bond.