Magnetic Hyperfine Structure and Zeeman Effect of the J=1, K-1=1 Transition of H2CO

The hyperfine structure and the Zeeman effect in the 1 10 →1 11 transition of H 2 CO has been studied with a high resolution beam maser spectrometer. The frequency of the most intense F =2→ F '=2 hyperfine component transition was measured to be 4829.649±0.0005 MHz. Theory of the magnetic hyperfine interaction in the presence of external static magnetic field was developed to analyze the experimental result. The spin-rotation interaction constants of proton nuclei in H 2 CO were determined as C x x =-5.0±1.5 KHz, C y y =4.2±1.5 KHz and C z z =-5.3±0.2 KHz. The rotational g -factors of H 2 CO were also obtained as G x x =-0.14±0.03, G y y =-0.14±0.03, G z z =-2.90±0.05 and | G x x - G y y |<0.036.