Dipole Moment Functions of Hydrogen Fluoride and Hydrogen Iodide Molecules Using AN Anharmonic Potential Function.

The spectral frequencies and line strengths of a number of vibration-rotation lines in the (1-0), (2-0),...,(5 -0) bands of HF and HI are available in the literature. In this dissertation the electric dipole matrix elements,. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). obtained from the line strengths, were used to determine the dipole moment coefficients, M(,n), in the expansion. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). where M(r) is the electric dipole moment function, r(,e) the equilibrium internuclear distance, and n = 0, 1, 2,...,5. The M(,n)'s were extracted from equations of the form. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). by a least squares fit. The wave functions (psi)(,vJ) and (psi)(,v'J') in this equation had been computed by solving the radial Schroedinger wave equation on a computer using a potential function of the form. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). The potential parameters, a(,i), were adjusted in such a way that the frequencies obtained from calculated energy levels agreed with the experimental ones. The least squares fit yielded the following dipole moment coefficients (in Debye):. M(,0) = 1.80306 M(,1) = 1.39079. M(,2) = -0.06916 M(,3) = -0.86677 for HF,. M(,4) = -0.5295 M(,5) = -1.0772. and. M(,0) = 0.447206 M(,1) = -0.072524. M(,2) = 0.51921 M(,3) = -2.06907 for HI. M(,4) = 0.11585 M(,5) = 2.48978. Similar studies have been carried out in the past by other authors, who used analytically obtained wave functions and only pure vibrational matrix elements in a system of six equations to determine the M(,n)'s. In the present work a large number of vibration-rotation matrix elements was used in the least squares fit to investigate the effect of vibration-rotation interaction on the dipole moment coefficients. It was found that M(,0) is not affected by it, M(,1), M(,2) and M(,3) only slightly, while M(,4) and M(,5) are somewhat more affected, particularly in the case of HI.