Rovibrational spectra of nonpolar (N2O)2 and Ar–N2O complexes in the 2v2 overtone region of N2O

Abstract Rovibrational spectra of Ar–N2O and nonpolar (N2O)2 van der Waals complexes have been recorded from 1157.2 to 1176.7 cm−1 in 2v2 overtone band region of N2O monomer using an external-cavity quantum cascade laser to probe the direct absorption in a slit supersonic jet expansion. One a/b hybrid vibrational band was identified for nonpolar (N2O)2, and one b-type vibrational band for Ar–N2O, respectively. Quantum chemical calculations of vibrational frequencies and infrared intensities of these two complexes were performed at the MP2/aug-cc-pvtz level of theory. The first vibrational band is assigned tentatively as a combination band of the intramolecular symmetric and anti-symmetric in-plane bending modes of nonpolar (N2O)2. The second vibrational band is assigned as an overtone band of the bending mode of Ar–N2O. Precise molecular constants have been derived for these two complexes. The band-origin is located at υ 0  = 1168.177584(76) cm−1 for Ar–N2O and υ 0  = 1165.218580(54) cm−1 for nonpolar (N2O)2, which shows a blue-shift by 0.0451 cm−1 for Ar-N2O and a red-shift by 2.9139 cm−1 for nonpolar (N2O)2 compared with that of the N2O (0200)-(0000) band, respectively.