We report the infrared spectrum of NO3 studied with a high-resolution Fourier transform spectrometer. By improving the setup of an absorption cell, the following eight bands were observed at 1127, 1132, 1134, 1173, 1413, 1492, 1562, 1927 cm-1 in the 1000-1930 cm-1 region. The 1127, 1132, 1134, and 1562 bands were not reported previously by matrix isolation spectroscopy, and these bands have been assigned to hot bands from the ν4 state (ν3 + ν4 ← ν4) and (ν3 + 2ν4 ← ν4). The analysis of the 1127 band with an E'-E' type spectral pattern has been carried out, and major molecular constants of the lower (ν4) state are determined as follows: B = 0.459 2222(60), C = 0.227 8233(40), Cζ4 = -0.042 063(15), and ν4 = 365.48419(43) cm-1. Two A'-E' type bands with band origin frequencies of 1132 and 1134 cm-1 are also assigned, indicating that the 1492 band is assignable to ν3 + ν4, in contrast to the previous ν3 assignment. A simultaneous analysis of the 1127, 1132, 1134, 1492 cm-1 bands has been carried out to give 46 molecular constants for the ν3 + ν4 and ν4 states. The molecular constants of the ν3 + ν4 A' states are different from those of the E' state, because of an effect of vibronic interaction from the B2E′ electronic state to the ν3 + ν4 E' state.
- FT IR spectroscopy
- Nitrate radical
- Vibration-rotation bands
- Vibrational assignment
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry