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⩽K_a⩽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, Δ_K, ε_aa, and η_aaaa between the ground and v₂=1 vibrational states were observed.