Hyperfine level-crossing spectroscopy of NH2 with dye-laser excitation

Hyperfine structure of a number of levels of the (0, 9, 0) and (0, 10, 0) vibrational states of the à ²A₁ state of NH₂ has been measured using the technique of magnetic level-crossing. A CW dye-laser served as an excitation source. The resolution achieved is ～ 3 MHz. The analyses have been aided by calculations of the relative fields for the level-crossings in terms of the parameters of a model hamiltonian, together with their relative intensities for linear and non-linear excitation. These calculations are presented for I = ½ and 1 for J = 1 ½, 2 ½, 3 ½, and 4 ½.

Hyperfine parameters for the (0, 10, 0) vibrational state are in good agreement with the one set of literature values, obtained using the independent method of intermodulated fluorescence.

We observe an apparent drop of 30 per cent in the Fermi contact parameter between the (0, 10, 0) and (0, 9, 0) levels. However, it is also found that the hyperfine splittings within the (0, 9, 0) state are not completely in accord with the simple model. These observations are briefly discussed in terms of the Renner effect and the s-p hybrid nature of the molecular orbital occupied by the unpaired electron.