Resonant two-photon ionization spectroscopy of the 13-electron triatomic Si2N

Resonant two-photon ionization spectra of 28Si2N, 28,29Si2N, and 28,30Si2N have been collected between 32 000 cm-1 and 36 000 cm-1. A fit of the rotationally resolved spectrum of the most intense band of 28Si2N at 34 314 cm-1 reveals the transition to be 2?+u ? X~ 2IIg,1/2- A molecular orbital analysis is made to justify the assignment. The geometric structure is determined to be linear and centrosymmetric in both the ground and excited state with r0 O(Si-N) = 1.6395 ? 0.0014 ? and rN(Si-N) = 1.6343 ? 0.0014 ?. The ionization energy is determined to be less than 8.51 eV.