Study on the Rotation of NO₂⁻ in KBr by Resonance Raman Scattering

Abstract

Emission from an NO₂⁻ ion in KBr is studied under resonant excitation with laser light at vibration-rotation structures of the ¹A₁→¹B₂ transition. Five rotational Raman lines are identified in a fundamental and over-tone vibrational transitions with Raman shift energies of +4.4, 0, −4.4, −10.0 and −14.5 cm⁻¹ from the vibrational transitions. A new assignment for the rotational structures in the absorption, emission and Raman spectra is proposed, which is based on a one-dimensional rotor in a hindering potential with four-fold symmetry. The rotational constants and hindering potentials are determined as A=1.3 cm⁻¹, V⁄A=4 and A′=1.7 cm⁻¹, V′⁄A′=8 for the ground and excited electronic state, respectively. These values suggest that the rotation occurs around an axis passing near an N-atom and perpendicular to the symmetry axis in the molecular plane.