以波长可调谐高功率脉冲激光器为激发源，采用共振增强多光子离化（REMPI）光谱技术，对SO2的里德堡态进行实验研究。在420~540 nm波长范围内，得到了与碱金属原子吸收光谱类似的共振增强多光子离化光谱。429.3 nm和452.3 nm处离化峰对应（4+1）共振增强五光子离化，529.4 nm处的离化峰对应（4+2）共振增强六光子离化过程。该离化谱峰序列对应于高激发态F1A2态的np（n=4，5，6）里德堡态序列。对529.4 nm处离化峰的精细扫描表明，该处离化峰呈现为近等间隔的谱峰结构，对应于SO2分子里德堡态4p（0, v2, 0）的共振增强多光子离化光谱序列。实验得到4p里德堡态弯曲振动的基振动角频率Δν2=(387.3±12.4) cm-1。

The Rydberg state of SO2 has been studied experimentally using the technology of resonance-enhanced multiphoton ionization (REMPI) spectra, where a wavelength tunable high-power pulse laser is used as the excitation source. The REMPI spectra similar to atomic absorption spectra of alkali metal have been obtained in the range of 420~540 nm. The ionization peaks appearing at 429.3 nm and 452.3 nm correspond to the (4+1) REMPI, and the ionization peak at 529.4 nm corresponds to the (4+2) REMPI. The higher electronically excited state appearing in the spectra should be assigned to the Rydberg state series converging to F1A2 with an np orbital (n=4, 5, 6). The scanning of the ionization peak with high precision at 529.4 nm shows that the spectral structure with nearly equal interval corresponds to the REMPI series of 4p（0, v2, 0） Rydberg state of SO2. The harmonic frequency of bending vibration levels of 4p Rydberg state Δν2 is calculated to be (387.3±12.4) cm-1.