Probing structural transitions of nanosize silicon clusters via anion photoelectron spectroscopy at 7.9 eV

Photoelectron spectra of silicon cluster anions as large as Si 35 − have been obtained with vacuum ultraviolet radiation at 157 nm (7.9 eV). The data show spectroscopic trends consistent with the structural transformation from prolate to more spherical clusters previously observed in ion mobility experiments. In addition, we observe signal at high electron binding energy that may be analogous to the second band seen in the photoemission spectrum of bulk silicon.