Journal of Chemical Physics, Vol.113, No.2, 602-610, 2000
Laser fluorescence excitation spectroscopy of the CAr van der Waals complex
Laser fluorescence excitation spectra of the CAr van der Waals complex, in the vicinity of the carbon 2s(2)2p3s P-3 degrees <-- 2s(2)2p(2 3)P and 2s2p(3 3)D degrees <-- 2s(2)2p(2 3)P atomic resonance transitions at 165.7 and 156.1 nm, respectively, are reported. A single, weak band was observed similar to 100 cm(-1) to the blue of the 2s(2)2p3s P-3 degrees <-- 2s(2)2p(2 3)P atomic transition. An excited-state (v('),0) progression correlating with the carbon atomic 2s2p(3 3)D degrees <--2s(2)2p(2 3)P transition was recorded near the 156.1 nm atomic transition and was assigned to the CAr F (3)Pi <-- X (3)Sigma(-) transition. The upper-state vibrational constants, omega(e)' = 31.82 +/- 0.34 cm(-1), omega(e)x(e)' = 3.58 +/- 0.11 cm(-1), were determined. The excited F (3)Pi state was found to be less strongly bound than the ground state: D-0' = 54.8 +/- 1 and D-0' = 120.4 +/- 1 cm(-1). Differences in the rotational contours of bands of the (CAr)-C-12 to (CAr)-C-13 isotopomers were ascribed to differences in the fine-structure splittings of the excited F (3)Pi state. The rotational constant B-e' = 0.112 +/-0.005 cm(-1) was estimated for the (CAr)-C-12 isotopomer. A Morse function was constructed to describe the potential energy curve of the F (3)Pi state. The CAr binding energy is compared with that of other diatomic complexes, and the role of predissociation in the decay of excited CAr states is discussed.