Triple-resonance spectroscopy on CH_3OH far-infared laser lines

Abstract
Intracavity triple-resonance spectroscopy in CH3OH far-infrared lasers has been extended to the microwave region. A triple-resonance signal at 13410.45(10) MHz was observed on the 224.5-μm CH3OH laser line optically pumped by a waveguide CO2 laser. The results confirm the assignment proposed for this line and improve the knowledge of A-state splitting in the v = 5 vibrational state.