The near-IR spectrum of NO(X̃2Π)-He detected through excitation into the Ã-state continuum: A joint experimental and theoretical study.

Abstract

We present the first measurement of a bound-state spectrum of the NO-He complex. The recorded spectrum is associated with the first overtone transition of the NO moiety. The IR absorption is detected by exciting the vibrationally excited complex to the Ã-state dissociation continuum. The resulting NO(A) fragment is subsequently ionized in the same laser pulse. We recorded two bands centered around the NO monomer rotational lines, Q11(0.5) and R11(0.5), consistent with an almost free rotation of the NO fragment within the complex. The origin of the spectrum is found at 3724.06 cm-1 blue shifted by 0.21 cm-1 from the corresponding NO monomer origin. The rotational structures of the spectrum are found to be in very good agreement with calculated spectra based on bound states derived from a set of high level ab initio potential energy surfaces [Kłos et al. J. Chem. Phys. 112, 2195 (2000)].