Rotationally Resolved Excitation Spectra Measured by Slow Electron Detachment from Si2.

Laser-induced delayed electron detachment from Si2- stored in an electrostatic ion storage ring was observed on the 10 microsecond time scale. The excitation spectra for photon energies near threshold show well-resolved multipeak structures, which are attributed to rovibronic transitions to the electronic excited state. This structure appears only in the signal measured with the delay. The occurrence of delayed detachment on such a long time scale is unusual for diatomic molecules, suggesting that both the autodetachment and fluorescence are slow.