(2+1) REMPI spectroscopy of the NO-CO, NO-N2, and NO-{N2, Ar} van der Waals complexes in the region of the 4s and 3d Rydberg states

We have collected (2 + 1) Resonance-Enhanced Multiphoton Ionization (REMPI) spectra of van der Waals complexes in which a NO molecule is attached to either CO, N-2, or both N-2 and Ar. The energy region probed corresponds to electronic transitions of uncomplexed NO(X-2 Pi) to the 4s and 3d Rydberg states, and we discuss the observed spectra in light of the expected perturbations to these electronic levels induced by complexation. We employ a model in which the van der Waals partners are assumed to reside within the Rydberg orbital, and discuss the importance of core penetration in the description of the electronic structure. By performing calculations on NO+ interacting with both N-2 and Ar, we identify the global minimum as being a non-planar structure. Further, the N-2 and Ar are found to interact with the NO+ largely independently, and we find some evidence for this from the REMPI spectrum of NO-{N-2, Ar}.