摘要：

Laser vaporization of a rotating metal target within a pulsed supersonic nozzle has been used to produce ultracold beams of copper clusters. Photoionization with an argon fluoride excimer laser followed by time-of-flight mass spectrometric analysis showed the cold beam to contain clusters in the range from 1 through 13 copper atoms. The ionization potential (IP) of the small clusters was seen to alternate above and below the 6.4-eV laser photon energy depending upon whether the cluster contained an een (high IP) or odd (low IP) number of copper atoms. The absorption spectrum of Cuwas recorded in the 4480 to 4660-A region by using two-color resonant two-photon ionization. The Cucluster beam was found to have translational, rotational, and vibrational temperatures of < 5, < 10, and 50 to 100K, respectively. In addition to the known B μ/sub u/ reverse arrow X μ/sub g/ band system, a new system was found in the same spectral range. Parameters for the new system were T/sub e/ = 21,867 +- 4 cm, omega'/sub e/ = 226 +- 3 cm, omega/sub e/ chi'/sub e/ = 3 +- 2 cm. The lifetime of the B state was found to be 35 +- 10 ns for the vibrational levels nu' = 0 and 1, and it is argued this short lifetime is likely due to predissociation. The lifetime of the new C state was found to be 1.0 +- 0.2 μs. 4 figures, 1 table

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