THE $\nu_{2}$ BAND OF HOCl

$^{1}$W. J. Lafferty, and W. B. Olson, J. Mol. Spectrosc. 120, 359 (1986)Author Institution: Université P. et M. Curie, 75252 Paris Cedux 05, France.; Université Libre, CP160, Av. F.D. Roosevelt, 1050 Bruxelles.; NIST, Gaithersburg, MA 20899.The main challenge encountered when measuring absolute intensities for hypochlorous acid is determining the partial pressure of this molecule in the sample since HOCl exists only in equilibrium with $H_{2}O$ and $Cl_{2}O$. Until now, studies dealing with intensity measurements of this molecule have relied on the equilibrum constant determined by other techniques. However, in this work we have used know line intensities of the pure rotational spectrum of HOCI determined from Stark effect measurements to obtain the concentration of this species in the sample mixture. The $\nu_{2}$ band of HOCI has been recorded between 550 and $2000 cm^{-1}$ at a resolution of $0.005 cm^{-1}$ using a Fourier transform spectrometer. About 136 and 70 intensities of well isolated lines were measured for $HO^{35}Cl$ and $HO^{37}Cl$ respectively. In order to calculate intensities, one most know precisely the wavefunctions. As noted $previously^{1}$, the $K_{a} = 5$ levels of the (010) state of the $^{35}ClOH$ molecule are perturbed by the $K_{a} = 4$ levels of the (002) vibrational state A calculation taking this interaction into account was performed allowing one to locate a few lines of the $2\nu_{3}$ band as well as to calculate the (010) rotational levels to within their experimental accuracy. Finally experimental intensities were calculated, and a precise transition moment operator for $\nu_{2}$ was obtaine