“…In the spectrum of Figure 1c, many vibronic bands are observed in the higher frequency side from the band origin, and these bands correspond well with the bands observed in the absorption spectrum in the vapor phase. 7 Low-frequency bands at 87, 188, 229, and 325 cm -1 , which were assigned as hot bands in the vapor phase spectrum, 7 should be ascribed to cold bands and correspond to 87, 191, 233, and 325 cm -1 , respectively, in the jet spectrum. Vibrational frequencies usually become lower with a electronic excitation because the electron is excited from a bonding orbital to an unstable antibonding orbital.…”