HIGH-RESOLUTION ROVIBRATIONAL ABSORPTION-SPECTRUM OF CO2-N2O

The rovibrational absorption spectrum of the weakly bound cluster CO2- N2O has been observed in the region of the nu(3) CO2 asymmetric stretc h (similar to 2350 cm(-1)). Clusters were formed by supersonic expansi on of a mixture of N2O:CO2 in a 4:1 ratio using He carrier gas. Approx imately 340 lines have been assigned. Both parallel and perpendicular transitions were observed. The ground state rotational constants A, B, and C are 0.293 924(12), 0.058 004(6), and 0.048 400(6) cm(-1), respe ctively. The quartic centrifugal distortion constants are D-j = 5.03(1 7) x 10(-7) cm(-1), D-jk = -3.92(9) x 10(-6) cm(-1), D-k = 1.26(2) x 1 0(-5) cm(-1), delta(j) = 1.61(92) x 10(-8) cm(-1), and delta(k) = 1.77 (80) x 10(-6) cm(-1). Ab initio calculations for several CO2-N2O equil ibrium structures have been done on the Hartree-Fock self-consistent f ield level using a 6-311g basis set, Moller-Plesset MP2 and MP3 calcu lations were carried out for the two possible slipped parallel configu rations of the dimer. The planar slipped parallel geometry with the ox ygen atom of N2O nearest the CO2 monomer was found to be the most stab le structure. The spectral constants and stabilization energies were c ompared to those of the CO2 and N2O homodimers. A planar slipped paral lel geometry is observed with the O of N2O nearly over the C of CO2. R (cm) and theta are 3.4701 Angstrom and 60.1 degrees, respectively, ass uming the CO2 and N2O are parallel to each other.