Van der Waals vibrations of NO-methane complexes in the A2∑+ state

The (1 + 1) resonance enhanced two-photon ionization spectra of NO-methane van der Waals (vdW) complexes associated with the A2∑+− X 2Π transition of the NO moiety were measured using a time-of-flight mass spectrometer. The band origin of NOCH4 vdW complex is determined as 44103.7 cm−1. In the low transition energy region of 44080–44180 cm−1, the origin band and two vdW bands were observed and each of the bands consisted of four peaks due to the internal rotation of methane. An analysis of the internal rotation gave the V3 anisotropic parameters of 114–153 and 35 cm−1 in the A2∑+ and X2Π states, respectively.