Université de Bordeaux-CNRS-CEA, CELIA, UMR5107, 33405 Talence, France.
Université de Bordeaux, ISM (CNRS-UMR 5255), 351 cours de la Libération, 33405 Talence Cedex, France.
Phys Chem Chem Phys. 2023 Jun 21;25(24):16246-16263. doi: 10.1039/d3cp01057k.
The photoionization of chiral molecules by elliptically polarized femtosecond laser pulses produces photoelectron angular distributions which show a strong and enantio-sensitive forward/backward asymmetry along the light propagation direction. We report on high precision measurements of this photoelectron elliptical dichroism (PEELD). Using an optical cavity to recycle the laser pulses and increase the signal-to-noise ratio, we determine enantiomeric excesses with a 0.04% precision with a low-power femtosecond laser (4 W) in a compact scheme. We perform momentum-resolved PEELD measurements in 16 molecules, from volatile terpenes to non-volatile amino acids and large iodoarenes. The results demonstrate the high structural sensitivity of PEELD, confirming the spectroscopic interest of this technique. Last, we show how a convolutional neural network can be used to retrieve the chemical and enantiomeric composition of a sample from the momentum-resolved PEELD maps.
手性分子的椭圆偏振飞秒激光脉冲光致电离产生的光电子角分布在光传播方向上表现出强烈的、对映体敏感的前向/后向不对称性。我们报告了这种光电子椭圆双折射（PEELD）的高精度测量结果。我们使用光学腔来回收激光脉冲并提高信噪比，从而在紧凑的方案中使用低功率飞秒激光（4 W）以 0.04%的精度确定对映体过量。我们在 16 种分子中进行了动量分辨的 PEELD 测量，从挥发性萜烯到非挥发性氨基酸和大的碘芳烃。结果表明，PEELD 具有很高的结构灵敏度，证实了该技术的光谱学意义。最后，我们展示了如何使用卷积神经网络从动量分辨的 PEELD 图谱中检索样品的化学和对映体组成。
