Anion photoelectron spectroscopy of small tin clusters

The anion photoelectron spectra of small tin clusters, Sn-x(-) (x = 1 through 12) are presented and compared with the anion photoelectron spectra of germanium clusters [Burton et al., J. Chem. Phys. 104, 2757 (1996)]. In general, the electron affinities of small tin clusters and germanium clusters are close. In most cases, the overall profiles of the tin cluster and analogous germanium cluster anion photoelectron spectra are remarkably similar. However, the tin cluster spectra frequently exhibit multiple electronic transitions where single broad electronic transitions appear in the germanium cluster spectra. The photoelectron spectrum of Sn-3(-) shows more dramatic disparity: The two lowest-energy electronic transitions observed in the photoelectron spectrum of Sn-3(-) appear to be nearly vertical, which is in sharp contrast to the vibrationally extended lowest-energy electronic transitions observed in the photoelectron spectra of Si-3(-) and Ge-3(-). The differences are attributed to a reduction of Jahn-Teller effects due to competition with large spin-orbit interaction in Sn-3(-). The lowest-lying spectral features are assigned to the A'(1) + e <-- E-5/2 and E " + e <-- E-5/2 transitions, where A'(1) and E " are the spin-orbit components of the (3)A'(2) neutral state. (C) 1999 American Institute of Physics. [S0021-9606(99)00611-X].