Absorption Spectrum of Borazine in the Vacuum Ultraviolet

The absorption spectrum of both vapor-phase and matrix-isolated borazine has been investigated in the 2000–1500-Å region. Three electronic transitions have been observed. The strongest absorption, with a maximum at 1650 Å, is assigned to the allowed E′1−A1′1 transition. Two weaker absorptions, with forbidden origins at 1975 and 1889 Å, are assigned to the forbidden transitions A2′1−A1′1 and A1′1−A1′1, respectively. The A2′1−A1′1 transition is made vibronically allowed by one quantum change in the ν16 and ν17 e′ vibrations. The vibration making allowed the A1′1−A1′1 transition could not be determined.