HIGH-RESOLUTION LASER-INDUCED FLUORESCENCE AND MICROWAVE ULTRAVIOLET DOUBLE-RESONANCE SPECTROSCOPY ON 1-CYANONAPHTHALENE

The rotationally resolved fluorescence excitation spectrum of the 0(0)0 band in the S1<--S0 transition of 1-cyanonaphthalene (CNN), at almost-equal-to 318 nm, has been recorded using laser-induced fluorescence in a molecular beam apparatus. This band exhibits pure a-type character and consists of almost-equal-to 600 lines at a rotational temperature of 2.5 K, each with a linewidth of 17 MHz. A microwave-ultraviolet double resonance experiment on the 0(0)0 band of CNN has been performed to verify the rotational assignments of the fluorescence excitation spectrum and to obtain more accurate rotational constants in both the ground and electronically excited states. The band origin of the 0(0)0 band is at 31411.114+/-0.003 cm-1 and the rotational constants are (in MHz) A'' = 1478.65 (2), B'' = 956.75 (1), C'' = 580.989 (7), A'-A '' = - 21.363 (9), B'- B'' = - 13.305 (5), and C'- C'' = - 8.167 (2),