FOURIER-TRANSFORM SPECTRA OF LASER-INDUCED FLUORESCENCE IN THE (2)PI(U)-(X)OVER-TILDE((2)PI(G)) TRANSITION OF (CUCL2)-CU-63-CL-37 - RENNER-TELLER AND K-DOUBLING INTERACTIONS IN THE (X)OVER-TILDE(0 2' 0) ROVIBRONIC LEVELS

Spectroscopic investigations of CuCl2 in its electronic ground state h ave been extended to transitions to the levels of the (0 2' 0) vibroni c multiplet. These transitions appear as weak P, R rotational lines in laser-induced fluorescence spectra recorded in the range 15 850-15 95 0 cm(-1). A single-mode ring dye laser, whose wavenumber was set near 16 100 cm(-1), excited a transition in the (2) Pi(u(3/2)), (upsilon') <-- X ($) over tilde (2) Pi(g(3/2)) (0 0 0) band, where upsilon' is at present an unidentified level of the (2) Pi(u), state. After treatmen t of rotational perturbations in the upper state, a model has been con structed for calculating these fluorescence lines, based on the effect ive Hamiltonian of D. R. Woodward, D. A. Fletcher, and J. M. Brown (Mo l. Phys. 62, 517-536, 1987; 68, 261-262, 1989) for the ground state. T he model was used to fit to 228 recorded lines with a nonlinear least- squares program; it reproduces the rotational structure (6 1/2 less th an or equal to J '' less than or equal to 80 1/2), and the Renner-Tell er and K-doubling patterns appearing in this band with a root-mean-squ are error of 0.010 cm(-1), which is comparable with the experimental a ccuracy. Effective values (in cm(-1)) have been obtained for the vibra tional energy of the (020) level (G(2) = 189.19(3)), for rotational an d centrifugal distortion constants (B-2 = 5.5221(1) X 10(-2) and D-2 = 7.0(2) X 10(-9)), for the Lambda- and K-doubling constants (q(2) = -3 .1(35) X 10(-5), p(2) = 0.0721(9), and q(upsilon) = -1.1 X 10(-4)), th e Renner constant (epsilon omega = -40.60(4)) and the vibronic constan t (g(K) = 9.877(8)) for the Omega = 3/2 spin-orbit component. (C) 1995 Academic Press, Inc.