Laser magnetic resonance spectroscopy of the ν2 fundamental band of HCO at 9.25 μm

Abstract

The ν2 bending fundamental (ν0=1080.76 cm−1) of the formyl radical, HCO, has been studied using CO2 laser magnetic resonance. Fluorine atoms from a discharge in CF4 were reacted with H2CO to form the short-lived HCO, which then flowed through an absorption cell located between the pole faces of an electromagnet and within the optical cavity of a CO2 laser. By means of the Zeeman effect, HCO, vibration-rotation transitions were tuned through resonance with the laser lines. Numerous resonances involving levels with 1⩽N⩽7 and 1⩽Ka⩽3 were assigned, and from analysis of the spectra accurate determinations of the band origin, rotational, centrifugal distortion, spin-rotation, and Fermi interaction parameters for ν2 were made. Fairly large changes in the values of A, ΔK, εaa, and ηaaaa between the ground and v2=1 vibrational states were observed.