Laser magnetic resonance spectrum of 13CH2 around 11 µm: determination of 13C hyperfine interactions and ν2 isotope shift for methylene

Abstract

Ten rotation–vibration transitions of the ν₂ (bending) fundamental band of ¹³CH₂ have been observed using the technique of CO₂ laser magnetic resonance in the 880 to 945 cm⁻¹ region. ¹³C substituted methylene was produced in a flow system by reacting ¹³CH₄ or ¹³CH₂CO with F atoms from a microwave discharge in CF₄. Analysis of the spectra yields a number of molecular parameters for ¹³CH₂. Specifically, the ¹³C isotope shift of ν₂ is −3.93 cm⁻¹ and the ¹³C Fermi contact hyperfine parameter is 238 ± 6 MHz for the ground vibrational state. The hyperfine parameters determined here for gas phase ¹³CH₂ are in fairly good agreement with those determined for matrix isolated ¹³CD₂ in earlier ESR experiments.