THE INFRARED-SPECTRUM AND STRUCTURE OF THE NITROUS-OXIDE TRIMER

Reported here are the first spectroscopic observations of the nitrous oxide trimer. Two rotationally resolved vibrational bands have been ob served using the optothermal detection method. The ground vibrational state rotational constants obtained from these spectra are A = 0.05260 6(40), B = 0.043571(15), and C = 0.028736(7) cm(-1). Ab initio calcula tions are also reported here, at the MP2/6 - 31 + G(2d, 2p) level, whi ch yield A = 0.05492, B = 0.01517, and C = 0.03052 cm(-1). The structu re of the nitrous oxide trimer can be thought of as a slightly distort ed dimer, which has a slipped parallel geometry [Z. S. Huang and R. E. Miller, J. Chem, Phys. 89, 5408 (1988)], with a third monomer unit ly ing above this dimer, This structure is similar to the recently observ ed nonplanar isomer of (CO2)(3) [M. J. Weida and D. J. Nesbitt, J. Che m. Phys. 105, 10, 210 (1996)]. (C) 1998 American Institute of Physics.