Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland.
Universität Kassel, Heinrich-Plett-Str. 40, 34132, Kassel, Germany.
Chemphyschem. 2022 Dec 16;23(24):e202200575. doi: 10.1002/cphc.202200575. Epub 2022 Sep 19.
Single-photon ionisation of enantiopure methyl p-tolyl sulfoxide by circularly polarised light at 133 nm shows remarkably strong photoelectron circular dichroism (PECD), which has been measured in a velocity-map-imaging spectrometer. Both enantiomers were measured, each showing a PECD of a similar magnitude (ca. 25 %). These experiments were carried out with a tabletop high-harmonic source with a photon energy of 9.3 eV, capable of ionising the electronic ground state of most organic and inorganic molecules. Ab-initio scattering calculations provide a theoretical value of the expected chiral asymmetry parameter, and agree very well with the measured values once orbital mixing via configuration interaction in the cation is taken into account. This study demonstrates a simple photoionisation scheme that can be readily applied to study the time-resolved PECD of photochemical reactions and suggests a pronounced sensitivity of PECD to electronic configuration interaction in the cation.
在 133nm 处用圆偏振光对旋光纯甲基对甲苯亚砜进行单光子离化，在速度映射成像光谱仪中显示出非常强的光电子圆二色性（PECD）。两种对映异构体都进行了测量，每个对映异构体都显示出相似大小的 PECD（约 25%）。这些实验是在具有 9.3eV 光子能量的台式高次谐波源中进行的，能够离解大多数有机和无机分子的电子基态。从头算散射计算提供了预期手性不对称参数的理论值，并且一旦考虑到阳离子中通过组态相互作用的轨道混合，就非常符合测量值。这项研究展示了一种简单的光离解方案，可用于研究光化学反应的时间分辨 PECD，并表明 PECD 对阳离子中电子组态相互作用具有明显的敏感性。
