Near-Infrared Emission Spectrum of NO

The emission spectrum of the vibration—rotation bands of the electronic ground state of nitric oxide has been observed in the 1.83–1.95- and 2.63–2.81-μ regions under moderately high resolution. The source of the spectrum was a high-tension discharge maintained through streaming nitric oxide gas at pressures of less than 1 atm. A detailed analysis of the 2–0, 3–;1, and 4–;2 bands, occurring at 2.69, 2.73, and 2.77 μ, respectively, has been carried out. Accurate values obtained for many of the rotational and vibrational constants associated with the 2II½ and Π322 substates of the electronic ground state are presented, including a value for the spin—orbit coupling constant A. Also, the effective rotational temperature of the emitting gas has been determined.