Fast Arthur, Meek Samuel A
Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
J Chem Phys. 2021 Mar 21;154(11):114304. doi: 10.1063/5.0042552.
We report absolute transition frequencies for the allowed transitions from the XΠ, v = 0, J″ = 3/2 rovibronic ground state of SH to the AΣ, v = 0 vibronic state. The frequencies have been determined with an uncertainty of less than 1 MHz, representing a more than 1000-fold improvement over previous measurements. Spectral traces are measured by scanning a frequency comb stabilized continuous-wave spectroscopy laser over the molecular transitions and detecting laser-induced fluorescence from SH molecules in a highly collimated molecular beam. To determine the absolute transition frequencies, the traces are fit with a quantum-mechanical model that accounts for saturation effects and shifts due to quantum interference. The model also provides estimates of the predissociation rate of the excited-state levels. Weighted averages of the hyperfine-resolved transition frequencies are computed in order to enable comparisons to measurements where the hyperfine structure is not resolved. These hyperfine-averaged frequencies indicate that the absolute transition frequencies determined in previous measurements were about ∼2.1 GHz (0.07 cm) too high. Finally, the measured transition frequencies are fit using an effective Hamiltonian model, resulting in more precise estimates of the spectroscopic constants.
我们报告了从SH的XΠ，v = 0，J″ = 3/2振转基态到AΣ，v = 0振动态的允许跃迁的绝对跃迁频率。这些频率的测定不确定度小于1 MHz，相较于之前的测量有超过1000倍的提升。通过在分子跃迁上扫描频率梳稳定的连续波光谱激光，并检测来自高度准直分子束中SH分子的激光诱导荧光来测量光谱轨迹。为了确定绝对跃迁频率，将这些轨迹与一个量子力学模型进行拟合，该模型考虑了饱和效应和量子干涉引起的频移。该模型还提供了激发态能级预解离速率的估计值。计算超精细分辨跃迁频率的加权平均值，以便能够与未分辨超精细结构的测量结果进行比较。这些超精细平均频率表明，先前测量中确定的绝对跃迁频率大约高了约2.1 GHz（0.07 cm）。最后，使用有效哈密顿量模型对测量的跃迁频率进行拟合，从而得到更精确的光谱常数估计值。
