Infrared-radiofrequency double resonance spectroscopy of CH3F using a color center laser

A tunable color center laser has been used as the infrared radiation source for infrared-radio-frequency double resonance spectroscopy. The A1–A2 splitting (J, K = 1, l = 1 and J, K = 2, l = −1) in the ν4 vibrational state of CH3F has been studied. This technique has also been used to measure the electric dipole moment for the ν4 state, which has been determined to be 1.8332(23) D.