Chiral Discrimination through Bielliptical High-Harmonic Spectroscopy
Chiral Discrimination through Bielliptical High-Harmonic Spectroscopy
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DOI：
10.1103/physrevx.8.031060
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发表时间：
2018-09-10
影响因子：
12.5
通讯作者：
Worner, Hans Jakob
中科院分区：
文献类型：
--
作者：
Baykusheva, Denitsa;Worner, Hans Jakob
分子手性在大多数生物化学过程中起着重要的作用。然而，手性敏感信号的观察和定量仍然极具挑战性，特别是在超快时间尺度和稀介质中。在这里，我们描述了一个全光学和超快的计划，用于检测分子中的手征动力学的实验实现。该技术是基于高次谐波产生的双色反向旋转飞秒激光脉冲的偏振状态可调从线性到圆形的组合。我们展示了两种不同的实现手性敏感的高谐波光谱的随机取向的甲基环氧乙烷分子在气相中的合奏。使用两个椭圆偏振场，我们观察到最大化谐波信号的椭圆度达到4.4 +/- 0.2%（在17.6 eV处）。使用两个圆偏振场，我们观察到圆二色性范围高达13 +/- 6%（28.3-33.1 eV）。我们的理论分析证实，所观察到的手征响应起源于亚飞秒电子动力学驱动的驱动激光场的磁分量。这一分配是支持的手征效应的强强度依赖性的实验观察和它的协议与理论。此外，我们报告和解释一个显着的变化的信号强度和二向色性与驱动场的椭圆度和谐波阶数。最后，我们证明了实验观测的电子空穴的形状的敏感性。这种技术的手征歧视将产生飞秒的时间分辨率时，集成在一个泵探测计划和亚飞秒分辨率的手征电荷迁移的自探测计划。
Molecular chirality plays an essential role in most biochemical processes. The observation and quantification of chirality-sensitive signals, however, remains extremely challenging, especially on ultrafast timescales and in dilute media. Here, we describe the experimental realization of an all-optical and ultrafast scheme for detecting chiral dynamics in molecules. This technique is based on high-harmonic generation by a combination of two-color counterrotating femtosecond laser pulses with polarization states tunable from linear to circular. We demonstrate two different implementations of chiral-sensitive high-harmonic spectroscopy on an ensemble of randomly oriented methyloxirane molecules in the gas phase. Using two elliptically polarized fields, we observe that the ellipticities maximizing the harmonic signal reach up to 4.4 +/- 0.2% (at 17.6 eV). Using two circularly polarized fields, we observe circular dichroisms ranging up to 13 +/- 6% (28.3-33.1 eV). Our theoretical analysis confirms that the observed chiral response originates from subfemtosecond electron dynamics driven by the magnetic component of the driving laser field. This assignment is supported by the experimental observation of a strong intensity dependence of the chiral effects and its agreement with theory. We moreover report and explain a pronounced variation of the signal strength and dichroism with the driving-field ellipticities and harmonic orders. Finally, we demonstrate the sensitivity of the experimental observables to the shape of the electron hole. This technique for chiral discrimination will yield femtosecond temporal resolution when integrated in a pump-probe scheme and subfemtosecond resolution on chiral charge migration in a self-probing scheme.