A Theory of the Broadening of the Infrared Absorption Spectra of Hydrogen-Bonded Species. I

C. A. Coulson, G. N. Robertson
1974 Proceedings of the Royal Society A  
A theory of the intramolecular contributions to the broadening of the r(XH) absorption bands of hydrogen-bonded species is proposed, which is able to describe both vibrational predissociation and the formation of sum and difference bands. A formal method is developed for finding the wavefunctions and complex energy eigenvalues of quasi-stationary excited vibrational states of a linear triatomic system with realistic interactions. The theory is ap plied to the Me2O.HCl system. I t is found th a
more » ... I t is found th a t predissociation broadening is negligible. The calculation of combination band intensities, and of the spread in energy of terms within such bands, wrill be reported in a subsequent paper. f P resen t address: D ep artm en t of Physics, U niv ersity of Cape Town, Rondebosch, C.P. South Africa. $ O ur n o ta tio n is described in appendix A. 11 [ 167 ] Vol. 337. A. | U npublished calculations suggest th a t th is is sm all, being perhaps of th e order of 0.1 cm -1 (R obertson 1970). J Thom as (1971) has recently located th e hydrogen-bond bending modes in th e CH 3C N .H F system . A lthough th e m ethod he uses is indirect an d difficult to m ake very accurate, his findings seem quite convincing.
doi:10.1098/rspa.1974.0044 fatcat:qnl4lu2vgvfwhcqjmx7tnvya34