紫外光区S_2分子激光诱导荧光光谱

The Laser-Induced Fluorescence Spectrum of Jet-Cooled Diatomic Sulfur in Ultraviolet Region

利用真空脉冲放电超声射流气体束(H_2S/Ar^3%混合气体)的方法产生了气相S_2分子,并研究了30 400~34 400cm^(-1)范围内S_2分子的时间分辨和基态振动频率分辨的激光诱导荧光光谱,获得了184支谱带的高分辨率(0.1cm^(-1))和低分辨率(0.3cm^(-1))转动光谱。实验观测并归属了S_2分子B_u^(Σ-)-X^3Σ_g^-和B″~3Π_u-X^3Σ_g^-共84支振动跃迁,分析得到了激发态B^3Σ_u^-态ν=0~9和B″~3Π_u态ν=2~12的分子常数以及B^3Σ_u^-态的基态平衡分子构型。由于S_2分子B^3Σ_u^-与B″~3Π_u态之间存在微扰,这两个电子激发态的振动能级间隔、自旋分裂常数和自旋-轨道分裂常数变化不规律,转动跃迁强度和跃迁选择定则存在异常,利用~3Σ-~3Π的齐次微扰哈密顿量定性地对这些异常光谱进行了解释,进一步丰富了S_2分子紫外区低能电子激发态的信息。

The time-resolved and vibrational emission-resolved laser-induced fluorescence（LIF）spectra of jet-cooled supersonic diatomic sulfur molecule S_2 have been studied in the range of 30 400~34 400cm^（-1）, and 184 b and s were observed with high（0.1cm^（-1）） and low（0.3cm^（-1））resolutions.84 vibrational transitions were assigned to the B^3Σ_u^--X^3Σ_g^- and B″~3Π_u-X^3Σ_g^-, and the molecular constants in the excited states B^3Σ_u^- ν=0~9 and B″~3Π_uν=2~12,including rotational constants,spin-orbit coupling constants,spin-rotation coupling constants, and spin-spin coupling constants,were obtained.The equilibrium molecular geometry in the vibronic ground state of B^3Σ_u^-was determined by high-resolution spectrum.As there is perturbation between the B^3Σ_u^- and B″~3Π_ustates of S_2 molecule,the vibrational level intervals,spin-spin coupling constants and spin-orbit coupling constants of B^3Σ_u^- and B″~3Π_ustates are anomalous variation,as well as the intensity of rotational transition and the transition selection rules.The anomalous behavior of the rovibrational spectra was qualitatively explained by the homogeneous perturbations between ~3Σ-~3Π states.