The assignment of molecular infrared spectra from a laser magnetic resonance spectrometer

Abstract

Mathematical techniques are presented which have proved useful in assigning the laser magnetic resonance pure-rotation spectrum of HO 2, i.e., useful in assigning an absorption spectrum obtained when molecular energy levels are Zeeman shifted by an external magnetic field until transition frequencies coincide with a fixed-frequency radiation source. The techniques described should have general applicability to the laser magnetic resonance vibration-rotation spectrum of any molecule in an orbitally nondegenerate electronic state and a doublet electronic spin state ( S = 1 2 ). Equations involving both Zeeman line positions and Zeeman line intensities are presented. These allow the assignment of M J quantum numbers, the determination of the spin-rotation interaction constant γ and rotational quantum number N for both the upper and the lower state, and the determination of the zero-field transition frequency. The equations can be used without prior knowledge of the molecular structure or energy levels.