YI-JEN WANG, CHIAO-WEI CHEN, ANTHONY J. MERER, YEN-CHU HSU, Institute of Atomic and Molecular Sciences, Academia Sinica, P. O. Box 23-166, Taipei 10617, Taiwan, R. O. C..

Under similar experimental conditions to our previous paper, the fluorescence lifetimes of the A states of C3-Ne and C3-Ar have been determined. The uncertainties in the measured lifetimes are estimated to be better than 10%. About 50 perpendicular bands and 11 parallel bands of the A-X system of C3 were used to probe the fluorescence lifetimes of the Ne and Ar complexes. It is not possible to reduce the backing pressure while measuring lifetimes of the complexes; we therefore reduced the average pressure of the chamber to 1-2 × 10-5 torr by lowering the repetition rate. No sign of predissociation was found in either complex. Transitions to high vibrational levels of the A state of C3, above 4500 cm-1, give weak laser-induced fluorescence signals, so that lifetime measurements are not possible for some of these bands. The lifetimes of the levels of the Ne complex lying below 4300 cm-1 are generally shorter than 300 ns, except for some levels with C-C stretch excitation. The lifetimes of the Ne complex behave quite similarly to those of C3. In contrast, the lifetimes of the Ar complex do not follow the vibrational dependence of the lifetimes of C3 and C3-Ne. We speculate that the complicated lifetime pattern observed in the Ar complex can be attributed to interactions with nearby triplet levels.