Laser Magnetic Double Resonance Spectra at 5 and 10μm

Abstract

Laser magnetic resonance (LMR) spectroscopy, in which molecular transitions are Zeeman-shifted into coincidence with fixed laser frequencies, is now a well-established technique for studying unstable molecules. It was first developed in the far-infrared to study pure rotational spectra; progress in this region has been reviewed by EVENSON et al. [1]. More recently, LMR has been used in the mid-infrared region of CO (5–8 μm) and CO2 (9–11 μm) lasers to study vibration-rotation spectra; this has been reviewed by MCKELLAR [2]. Infrared-radiofrequency or -microwave double resonance [3] is another fruitful spectroscopic technique that utilizes mid-infrared lasers. This paper presents some results combining the double resonance and LMR techniques. Such a combination yields precise optically-detected EPR measurements within excited and ground vibrational levels, and can also serve as a useful aid for the assignment of difficult LMR spectra. Our technique is analogous to the combination of infrared-microwave double resonance and CO2 laser Stark spectroscopy used by TANAKA et al. [4], and of infrared-optical double resonance and CO2 LMR used by AMANO et al. [5].