The electronic structures of triplet S₂ ground and excited states are studied by ab initio molecular orbital and configuration interaction calculation. Potential energy curves correlated with $\text{S}({}^3\text{P})+\text{S}({}^3\text{P})$ and $\text{S}({}^3\text{P})+\text{S}({}^1\text{D})$ at the dissociation limit are evaluated, and electronic terms for a total of 11 states are assigned. Transition dipole moments, as a function of internuclear distance, are determined for two allowed transitions to ${\text{B}}^{″3}{\mathrm{\Pi }}_u$ and ${\text{B}}^3{\mathrm{\Sigma }}_u^{-}$ excited states. The total absorption cross-sections are computed to estimate isotope-fractionation constants, $∊$, for four most common isotopologues: ${}^{32}{\text{S}}^{32}\text{S}$, ${}^{32}{\text{S}}^{33}\text{S}$, ${}^{32}{\text{S}}^{34}\text{S}$, and ${}^{32}{\text{S}}^{36}\text{S}$ by quantum close-coupling (R-matrix) expansion approach and they are found to lie in a mostly opaque to competing absorbers spectral window. We suggest that the photochemistry and isotopic effects of S₂ are of significant importance and provide data showing high sensitivity of mass-independent fractionation to excitation wavelength. Zero-point energy based constants ${∊}^{\mathit{ZPE}}$ are estimated as well to compare with the obtained isotope effects and two modes for MIF are present in three-isotope plots; large isotopic effects were observed for both ${}^{36}\text{S}$ and ${}^{33}\text{S}$ with an excitation wavelength-dependent fluctuation.

通过从头算分子轨道和构型相互作用计算研究了三重态S ₂基态和激发态的电子结构。势能曲线与$\text{小号}（{}^3\text{P}）+\text{小号}（{}^3\text{P}）$ 和 $\text{小号}（{}^3\text{P}）+\text{小号}（{}^{\mathrm{1个}}\text{d}）$评估解离极限下的，并分配了总共11个状态的电子术语。对于两个允许的跃迁，确定跃迁偶极矩作为核间距的函数。${\text{乙}}^{\text{'}\text{'}3}{\mathrm{\Pi }}_{ü}$ 和 ${\text{乙}}^3{\mathrm{\Sigma }}_{ü}^{--}$兴奋的状态。计算总吸收截面以估算同位素分馏常数，$∊$，用于四种最常见的同位素异构体： ${}^{32}{\text{小号}}^{32}\text{小号}$， ${}^{32}{\text{小号}}^{33}\text{小号}$， ${}^{32}{\text{小号}}^{34}\text{小号}$， 和 ${}^{32}{\text{小号}}^{36}\text{小号}$通过量子紧密耦合（R-矩阵）扩展方法，发现它们位于竞争吸收体光谱窗口的大部分不透明的位置。我们认为，S ₂的光化学和同位素效应非常重要，并提供了数据，表明质量无关的分馏对激发波长具有很高的敏感性。基于零点能量的常数${∊}^{\mathit{ZPE}}$还要进行估算，以与获得的同位素效应进行比较，并且在三同位素图中存在两种MIF模式。两者均观察到较大的同位素效应${}^{36}\text{小号}$ 和 ${}^{33}\text{小号}$ 具有与激发波长有关的波动。