Magnetic Hyperfine Spectrum of H 2 CO by a Maser

The magnetic hyperfine structure in J =3, K -1 =1, Δ J =0 transition of formaldehyde at 29 Gc/sec was studied by a beam type maser spectrometer. The hyperfine components corresponding to Δ F =0 transitions were observed with good signal-to-noise ratio. The splittings are measured as 23.0 kc/sec and 10.4 kc/sec which are compared with theory. As well as the I · J coupling, spin-spin interaction term I 1 · I 2 between the two protons is fairly large and cannot be neglected. Coupling constants were determined as µ N 2 g H 2 r -3 =19.9 kc/sec and \(∑g{Jg}²(A1g+A2g){=}54.6\) kc/sec.