Stark Effect of the Absorption Line of Methane Observed by the 3.391 μm He–Ne Maser

Abstract

The Stark effect in CH₄ which has no permanent dipole moment in the ground vibrational state is observed on one component line at 2947.802 cm⁻¹ of the P(7) line in the ν₃ band by a magnetically tuned infrared maser. The effect is interpreted on the basis of the second-order induced dipole moment in the degenerate vibrational state which has the F₂ symmetry. The magnitude of the induced dipole moment of CH₄ in the ν₃ vibrational mode is evaluated from the observed Stark effect.