The Ti:Saphire laser operated within 13800 - 11800 cm${}^{-1}$ range was used to excite the $c^3{\Sigma }^{+}$ state of KCs molecule directly from the ground $X^1{\Sigma }^{+}$ state. The laser-induced fluorescence (LIF) spectra of the $c^3{\Sigma }^{+}\to a^3{\Sigma }^{+}$ transition were recorded with Fourier-transform spectrometer within 8000 to 10000 cm${}^{-1}$ range. Overall 673 rovibronic term values belonging to both $e/f$-components of the $c^3{\Sigma }^{+}(\Omega =1^{\pm })$ state of ${}^{39}$KCs, covering vibrational levels from $v$ = 0 to about 45, and rotational levels $J\in [11,149]$ were determined with the accuracy of about 0.01 cm${}^{-1}$; among them 7 values for ${}^{41}$KCs. The experimental term values with $v\in [0,22]$ were involved in a direct point-wise potential reconstruction for the $c^3{\Sigma }^{+}(\Omega =1^{\pm })$ state, which takes into account the $\Omega$-doubling effect caused by the spin-rotational interaction with the nearby $c^3{\Sigma }^{+}(\Omega =0^{-})$ state. The analysis and interpretation were facilitated by the fully-relativistic coupled cluster calculation of the potential energy curves for the $B^1\Pi$, $c^3{\Sigma }^{+}$, and $b^3\Pi$ states, as well as of spin-forbidden $c-X$ and spin-allowed $c-a$ transition dipole moments; radiative lifetimes and vibronic branching ratios were calculated. A comparison of relative intensity distributions measured in vibrational $c\to a$ LIF progressions with their theoretical counterparts unambiguously confirms the vibrational assignment suggested in [J. Szczepkowski, et al., JQSRT, 204, 133–137 (2018)].

Ti:Saphire 激光器在 13800 - 11800 cm 范围内运行${}^{-1}$ 范围被用来激发 $C^3{\Sigma }^{+}$ 直接来自地面的 KCs 分子状态 $X^1{\Sigma }^{+}$状态。激光诱导荧光 (LIF) 光谱$C^3{\Sigma }^{+}\to {\mathrm{一种}}^3{\Sigma }^{+}$ 在 8000 到 10000 cm 内用傅立叶变换光谱仪记录转变${}^{-1}$范围。总共 673 个 rovibronic 术语值属于两者$\mathrm{电子}/F$- 的组成部分 $C^3{\Sigma }^{+}(\Omega =1^{\pm })$ 的状态 ${}^{39}$KCs，涵盖从 $v$ = 0 到大约 45，以及旋转级别 $J\in [11,149]$ 测定精度约为 0.01 cm${}^{-1}$; 其中 7 个值为${}^{41}$KCs。实验项值与$v\in [0,22]$ 参与了直接逐点潜在重建 $C^3{\Sigma }^{+}(\Omega =1^{\pm })$ 状态，其中考虑到 $\Omega$-由与附近的自旋旋转相互作用引起的加倍效应 $C^3{\Sigma }^{+}(\Omega =0^{-})$状态。对势能曲线的完全相对论耦合聚类计算促进了分析和解释。${乙}^1\Pi$, $C^3{\Sigma }^{+}$， 和 ${乙}^3\Pi$ 状态，以及自旋禁止的 $C-X$ 并允许自旋 $C-\mathrm{一种}$跃迁偶极矩；计算了辐射寿命和振动分支比。振动测量中相对强度分布的比较$C\to \mathrm{一种}$LIF 进展及其理论对应物明确证实了 [ J. Szczepkowski, et al., JQSRT, 204 , 133–137 (2018)] 中建议的振动分配。