Laser magnetic resonance spectrum of the ν2 band of PH2

The ν2 bending fundamental band (ν0=1101.908 cm−1) of PH2 in the ? 2B1 ground electronic state has been studied using CO2 laser magnetic resonance in the 9.0 to 9.6 μm region. The short-lived PH2 radicals were produced in a flow system by the reaction of H atoms with PH3 molecules. A total of 25 molecular parameters (3 rotational, 5 distortion, and 4 spin-rotation constants in each of the (000) and (010) vibrational states, plus the ν2 band origin) have been determined from a least-squares fit of 122 observed resonances. The (000) state parameters are more accurate than, and in satisfactory agreement with, previous spectroscopic determinations, and the changes in the parameters upon excitation of the ν2 bending mode are discussed.