The He I valence photoelectron spectrum ofC 70 in the gas phase

Abstract

The high-resolution He I photoelectron spectrum of C 70 in the gas phase is reported and compared with that of C 60 and theoretical calculations. Similar to C 60, the C 70 spectrum shows two separate valence ionization band envelopes in the low energy region, but there are more separate ion states visible within the two envelopes. The first envelope of overlapping ionizations spans from about 7.3 to 8.8 eV, and the second from about 8.9 to 10.3 eV. The greater complexity of the C 70 spectrum compared to that of C 60 is expected due to the lower symmetry of C 70 and the ten additional π electrons from the additional carbon atoms. The first vertical ionization energy is 7.47 ± 0.02 eV, which is destabilized 0.17 eV from that of C 60.