Sub-Doppler resolution spectroscopy of CH3D has been carried out from 88.6 to 93.1 THz. 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 4 kHz. 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.
ASJC Scopus subject areas