JOURNAL OF MOLECULAR SPECTROSCOPY 81, 3 16-326 (1980) Tunable Laser Study of the vlo + vll Band of Cyclopropane

Diode laser measurements of the vi0 + Y, ~ (1,of = 22) perpendicular band of cyclopropane have led to the assignments of roughly 600 lines in the 1880-1920~cm- ’ region. Most of the spectra were recorded and stored in digital form using a rapid-scan mode of operating the laser. These spectra were calibrated, with the aid of a computer, by reference to the R lines of the V, + V, band of N20. The ground state constants we obtained are (in cm-‘) B = 0.670240 + 2.4 x lO-5, D, = (1.090 ” 0.054) x lO-6, DJx = (- 1.29 k 0.19) x lO-6, DK = (0.2 f 1.1) x 10m6. The excited state levels are perturbed at 1argeJ values, presumably by Coriolis couplings between the active E’(I tot = k2) and the inactive A’(/,,, = 0) states. Effective values for the excited state constants were obtained by considering only the J < 15 levels. The AI-AZ splittings in the K ’ = 1 excited states were observed to vary as qertJ(J + 1), with qerr = (2.17 2 0.17) x lo- ’ cm-‘. I