Atomic Si was produced in a pulsed high-voltage discharge jet expansion of a gaseous mixture of tetramethylsilane in helium. Its atomic transitions were characterized by a single color (1 + 1) resonance-enhanced multiphoton ionization (REMPI) technique in the one-photon energy range of 38 466–46 075 cm⁻¹. Based on the mass analysis of the discharge species using vacuum ultraviolet laser single-photon ionization time-of-flight mass spectrometry, which provides a means to characterize the species produced by the discharge source, various species including atomic Si, silicon hydrides (SiH_a, a = 0–3), hydrogenated silicon carbides (Si_xC_yH_z), and hydrocarbon species (C_mH_n) were generated in the pulsed high-voltage discharge jet expansion of tetramethylsilane. The REMPI spectroscopic characterization of the mass-selected species with 28 amu showed a total of 26 lines, all of which were assigned to the electronic transitions of neutral Si atoms. 10 out of the 26 lines were from spin-forbidden transitions. Among them are two “new” lines that were not listed in the M.I.T. Wavelength Tables or NIST Atomic Spectra Database. They were observed with good signal intensity at 43 551.76 cm⁻¹ (XVIII) and 44 201.34 cm⁻¹ (XX) and assigned to 3s²3p3d[³F⁰₂] ← 3s²3p²[¹D₂] and 3s²3p3d[³P⁰₂] ← 3s²3p²[¹D₂] transitions, respectively. In addition, 3 lines observed at 38 790.14 cm⁻¹ (I), 41 306.00 cm⁻¹ (XVI), and 43 634.78 cm⁻¹ (XIX), that had been previously reported in the literature, but with no assignment, were assigned to the spin-forbidden transitions of 3s²3p3d[³D⁰₁] ← 3s²3p²[¹S₀], 3s²3p4d[³P⁰₁] ← 3s²3p²[¹S₀] and 3s²3p3d[³F⁰₃] ← 3s²3p²[¹D₂], respectively. The use of a pulsed high-voltage electric discharge jet coupled with mass-selective REMPI has been shown as a sensitive and powerful technique to generate a rich variety of atomic and molecular species and to probe their electronic transitions with increased sensitivity.

中文翻译：

---

使用脉冲放电和共振增强多光子电离技术表征Si原子跃迁

在氦气中四甲基硅烷的气体混合物的脉冲高压放电喷射膨胀中产生了原子硅。其原子跃迁的特征是在38 466–46 075 cm ^-1的单光子能量范围内使用单色（1 +1）共振增强多光子电离（REMPI）技术。基于使用真空紫外激光单光子电离飞行时间质谱对放电物质进行质量分析，该方法可表征放电源产生的物质，包括原子硅，氢化硅（SiH _a，a = 0–3），氢化碳化硅（Si _x C _y H _z）和碳氢化合物（C _m在四甲基硅烷的脉冲高压放电射流膨胀中产生H _n）。具有28 amu的质量选择物种的REMPI光谱表征显示总共有26条谱线，所有谱线都分配给中性Si原子的电子跃迁。26条线中的10条来自自旋禁止跃迁。其中有两条未在MIT波长表或NIST原子光谱数据库中列出的“新”行。在43 551.76 cm ^-1（XVIII）和44 201.34 cm ^-1（XX）处观察到它们具有良好的信号强度，并被指定为3s ² 3p3d [ ³ F ⁰ ₂ ]←3s ² 3p ² [ ¹ D₂ ]和3s ² 3p3d [ ³ P ⁰ ₂ ]←3s ² 3p ² [ ¹ D ₂ ]转换。另外，以前在文献中曾报道过但未分配的3条线分别为38 790.14 cm ^-1（I），41 306.00 cm ^-1（XVI）和43 634.78 cm ^-1（XIX）。分配给3s ² 3p3d [ ³ D ⁰ ₁ ]←3s ² 3p ² [ ¹ S ₀ ]，3s ² 3p4d [³ P ⁰ ₁ ]←3s ² 3p ² [ ¹ S ₀ ]和3s ² 3p3d [ ³ F ⁰ ₃ ]←3s ² 3p ² [ ¹ D ₂ ]。脉冲高压放电喷嘴与质量选择性REMPI结合使用已被证明是一种灵敏而强大的技术，可以产生多种多样的原子和分子种类，并以更高的灵敏度探测其电子跃迁。