紫外光区S_2分子激光诱导荧光光谱
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摘要
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.
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.
引文
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