UV laser excited fluorescence spectroscopy of the jet-cooled copper dimer

UV laser excited fluorescence spectra of the jet-cooled copper dimer are reported. Cu2 is produced via laser vaporization of the metal inside the throat of a pulsed, supersonic nozzle. Strong fluorescence is observed upon excitation of 63Cu2 in the range 287–324 nm, corresponding to several v″=0 bands of the II–X transition recently found in excitation using resonant two-photon ionization Smalley et al., J. Chem. Phys. 78, 2866 (1983). The II–X emission spectra are characterized by extremely long progressions in the ground state vibration, enabling us to measure G(v) and ΔGv+1/2 values over the range v=0–72. This data has been fit to yield improved vibrational constants for 63Cu2 X 1Σ+g: ωe =266.43±0.59 cm−1, ωexe =1.035±0.030 cm−1, ωeye =+(1.70±0.58)×10−3 cm−1, and ωeze =−(1.78±0.37)×10−5 cm−1. The G(v) data has also been fit to a near-dissociation expansion which incorporates the correct limiting behavior of G(v), determined by the asymptotic inverse power contribution to the potential. This fit gives an improved dissociation energy for the dimer, and the vibrational index at dissociation: De =16 760±200 cm−1 and vD =128±5.