Rovibrational intensities in the nu(4) band of ammonia

Absolute line intensities of sixteen rovibrational transitions in the v(4) band of (NH3)-N-14 were measured around 1800 cm(-1) using a tunable diode l aser spectrometer with a sweep modulation of the laser frequency, Individua l laser scans over the line region were recorded to disk storage separately and the spectrum accumulation was performed off-line using a computer to r educe a significant line broadening because of a lower accuracy of the hard ware on-line accumulation. From integrated absorption coefficients obtained by the numerical analysis of the measured line profile, the effective transition moments of individua l rovibrational lines were derived. Using the second order perturbation the ory of the transition moment of rovibrational transitions of the symmetric top molecules, the effective vibrational transition moments for the v(4) fu ndamental band of (NH3)-N-14 were estimated. (C) 1999 Elsevier Science B.V. All rights reserved.