Infrared laser spectroscopy of the ν3-ν4 difference band and detection of the ν3 band of NO3

Abstract The infrared diode laser spectrum of the ν3-ν4 difference band of 14NO3 has been observed in the 690 cm−1 region. By fixing the lower state (v4 = 1) constants to the previously determined values, molecular constants in v3 = 1 have been determined for the first time : the vibrational energy E3 = 1054.13679(69) cm−1, the rotational constants B3 = 0.4562291(41), C3 = 0.2274567(53) cm−1, the first-order Coriolis coupling constant Cζ3 = 0.0032073(99) cm−1, and the spin–orbit interaction constant aeff = –0.03979(70) cm−1, with one standard deviation in parentheses. The ν3 fundamental band has been detected with weaker intensity than the ν3 + ν4 band by a factor of ~ 2000.