Abstract: Using an excimer pumped dye laser system, the multiphoton ionization MPI spectrum PH_3 was investigated between 300-640 nm. More than 20 bands have been recorded and a primary assignment has been made.
Near 20 bands observed in the range of 351-398 nm (Fig.3) are suggested to be a (2+1) excitation via PH_3 (Ã) state which was continuum observed in the absorption spectra. However, an estimated lifetime of 5×10~(-13) s for PH_3 (Ã) state still allows a subseqent excitation with a rate of 10~(12) s~(-1). The spectral bands of (Ã←X) exhib and an average interval of 263 cm~(-1).
Some weak bands between 460—495 nm are asigned to be (3+1) ionization via B state. A new formula [Formula (2)] modifies the original one which was suggested by Humphiries et al.~[1].
Six bands in 428—452 nm and four bands in 385—398 nm are assigned to the (3+1) MPI spectra via C and D states respectively. The term value of D state is estimated to be≤75567 cm~(-1), and ω_0 is about 510 cm~(-1).