Laser induced fluorescence of the PH2 radical
Abstract
A pulsed dye laser has been used to excite PH2 radicals from the 2B1 to the 2A1 state. The radiative lifetime of the excited state is 4 ± 1 µs for v′2= 0–3 and decreases to 0.35 µs for v′2= 4. Weak, short lived fluorescence excited at higher frequencies could not be positively assigned to v′2= 5. The quenching rate constant for hydrogen increases steadily from 1.24 × 1010 dm3 mol–1 s–1 for v′2= 0 to ≈1.6 × 1011 dm3 mol–1 s–1 at v′2= 4. Below 22 000 cm–1 the rotational and vibrational structure corresponds to that expected on the basis of the known absorption spectrum of PH2.