摘要：

Chromium clusters were prepared in a supersonic molecular beam by using a pulsed laser vaporization source. Resonant two-photon ionization (R2PI) spectroscopic scans were made with mass-selective detection for the chromium dimer. A single rovibronic band was found near 4600 angstrom and rotationally resolved for the /sup 50/Cr/sup 52/Cr, /sup 52/Cr/sub 2/, and /sup 52/Cr/sup 54/Cr isotopic species. The band was assigned as the A /sup 1/..sigma../sub u//sup +/reverse arrowX/sup 1/..sigma../sup +/O-O transition of Cr/sub 2/. Measurement of rotational constants confirmed earlier work of Efremov et al. where the same band system was observed upon flash photolysis of Cr(CO)/sub 6/. Rotational analysis concludes unequivocally that the bond length (r..xi..) in the v = O level of the /sup 1/..sigma../sub g//sup +/ ground state of /sup 52/Cr/sub 2/ is 1.68 +/- 0.01 angstrom.

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