Rösch Daniel, Almeida Raybel, Sztáray Bálint, Osborn David L
Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States.
Department of Chemistry, University of the Pacific, Stockton, California 95211, United States.
J Phys Chem A. 2022 Mar 17;126(10):1761-1774. doi: 10.1021/acs.jpca.1c10293. Epub 2022 Mar 8.
We present a new photoelectron photoion coincidence (PEPICO) spectrometer that combines high mass resolution of cations with independently adjustable velocity map imaging of both cations and electrons. We photoionize atoms and molecules using fixed-frequency vacuum ultraviolet radiation. Mass-resolved photoelectron spectra associated with each cation's mass-to-charge ratio can be obtained by inversion of the photoelectron image. The mass-resolved photoelectron spectra enable kinetic time-resolved probing of chemical reactions with isomeric resolution using fixed-frequency radiation sources amenable to small laboratory settings. The instrument accommodates a variety of sample delivery sources to explore a broad range of physical chemistry. To demonstrate the time-resolved capabilities of the instrument, we study the 193 nm photodissociation of SO via the (B) ← ̃(A) transition. In addition to the well-documented O(P) + SO(Σ) channel, we observe direct evidence for a small yield of S(P) + O(Σ) as a primary photodissociation product channel, which may impact sulfur mass-independent fractionation chemistry.
我们展示了一种新型的光电子光离子符合（PEPICO）光谱仪，它将阳离子的高质量分辨率与阳离子和电子的独立可调速度成像相结合。我们使用固定频率的真空紫外辐射对原子和分子进行光离子化。通过光电子图像的反演，可以获得与每个阳离子的质荷比相关的质量分辨光电子能谱。质量分辨光电子能谱能够使用适用于小型实验室环境的固定频率辐射源，以异构体分辨率对化学反应进行动力学时间分辨探测。该仪器可容纳多种样品输送源，以探索广泛的物理化学领域。为了展示该仪器的时间分辨能力，我们研究了SO通过（B）← ̃（A）跃迁的193nm光解离。除了有充分记录的O（P）+SO（Σ）通道外，我们还观察到直接证据，表明作为主要光解离产物通道，有少量的S（P）+O（Σ）产生，这可能会影响硫的质量无关分馏化学。
