A1–A2 splitting of CH3D

Abstract

Sub-Doppler resolution spectroscopy of CH3D has been carried out from 88.6 to 93.1THz. Thirty transitions of the ν1 and ν4 bands from the low-J and K=3 levels are observed, and the A1–A2 splitting is resolved for twenty-three of the thirty transitions. The absolute frequencies are determined with a typical uncertainty of 4kHz. The effective A1–A2 splitting constant of the K=3 levels is 2h3,v=0=(1.5641±0.0026) Hz for the ground vibrational state, and those of the K=3 levels for the v1=1 state and of the (K=2, l=−1) and (K=4, l=+1) levels for the v4=1 state are also determined.