LINE POSITIONS AND INTENSITIES IN THE VIBRATIONAL SYSTEM 2-NU-(2)/NU-(2)+NU-(4)/2-NU-(4)/NU-(1)/NU-(3) OF ARSINE

Fourier transform spectra were recorded between 1650 and 2350 cm(-1) with an unapodized resolution of about 0.0023 cm(-1), in order to determine upper state energy and intensity parameters relative to the pentad system 2v(2)/v(2) + v(4)/2v(4)/v(1)/v(3) of ASH(3). Already published assignments for v(1) and v(3) were completed up to J' = 16, and up to J' = 12 for the three weaker bands 2v(2), v(2) + v(4), and 2v(4). On the whole, 4897 transitions were assigned, 2194 of them being perturbation-allowed transitions. Moreover, due to the high resolution, close to the full Doppler width, individual line positions of many multiplets previously unresolved in v(1) and v(3) have been obtained. To achieve an accurate analysis of the data, it was necessary to take into account all the vibrational couplings expected within the pentad system. A set of 53 parameters was used to fit the upper state energy levels with a rms deviation of 7.65 x 10(-3) cm(-1): only two parameters are associated to Fermi-type couplings but no less than 10 parameters are required to describe the strong Coriolis couplings between normal modes 2 and 4. A set of 1894 absolute line intensities was measured and used for the intensity fit. Eleven parameters are necessary to fit the experimental intensities with a rms deviation equal to 7.36%. Band strengths (in cm(-2). atm(-1) at 296 K) were estimated as 1.67(12) for 2v(2), 3.27(12) for v(2) + v(4), 6.85(21) for 2v(4), 257.2(6.1) for v(1), and 696.9(16.5) for v(3). The band strengths obtained for v(1) and v(3) are in good agreement with the previous results of V. Dana, J.-Y. Mandin, G. Tarrago, W. B. Olson, and B. Bezard (J. Mol. Spectrosc. 159, 468-480, 1993). The energy and intensity parameters derived from the analysis were used to produce a prediction of AsH3 line positions and intensities for the five bands 2v(2), v(2) + v(4), 2v(4), v(1), and v(3), in view of their interest to planetary applications. (C) 1995 Academic Press, Inc.