Resonance Enhanced Multiphoton Ionization Spectrum of SO_2 in the range of 420～540nm

摘要

The resonance enhanced multiphoton ionization (REMPI) spectrum of SO_2 in the region of 420～540nm is obtained with a picosecond Nd:YAG laser pumped an Optical Parameter Generator and Optical Parameter Amplifier as radiation source,. The ionization pathway is analyzed. SO_2 molecule is ionized though (4+1) or (4+2) process and via 4p, 5p and 6p Rydberg resonant states. The near quintic variation of the ionization signal versus laser intensity verified this conclusion further. So the spectral lines can be assigned to np Rydberg series. The adiabatic ionization potential and the quantum defect of SO_2 are obtained based on the experimental datum, which is 99586 cm~(-1) and 1.85 respectively.