Photoexcitation circular dichroism in chiral molecules
Photoexcitation circular dichroism in chiral molecules
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DOI：
10.1038/s41567-017-0038-z
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发表时间：
2018-05-01
期刊：
影响因子：
19.6
通讯作者：
Blanchet, V.
中科院分区：
文献类型：
--
作者：
Beaulieu, S.;Comby, A.;Blanchet, V.
手征效应出现在各种各样的自然现象中，在科学中具有根本的重要性，从粒子物理学到超材料。手性鉴别的标准技术光吸收圆二色性依赖于手性介质的磁性，产生极弱的手性响应。在这里，我们提出并证明了一个数量级更敏感的中性分子的圆二色性类型：光激发圆二色性。这种技术不依赖于弱磁效应，而是利用超短圆偏振光激发的束缚电子的相干螺旋运动。它的结果在一个超快的手性响应和有效的激发宏观手性密度在一个最初的各向同性合奏随机取向的手性分子。我们探测这种激发使用线性偏振激光脉冲，没有进一步的手征相互作用的帮助。我们的时间分辨研究的振动手性动力学开辟了一条途径，有效地启动，控制和监测的手性化学变化的中性分子在电子水平。
Chiral effects appear in a wide variety of natural phenomena and are of fundamental importance in science, from particle physics to metamaterials. The standard technique of chiral discrimination-photoabsorption circular dichroism-relies on the magnetic properties of a chiral medium and yields an extremely weak chiral response. Here, we propose and demonstrate an orders of magnitude more sensitive type of circular dichroism in neutral molecules: photoexcitation circular dichroism. This technique does not rely on weak magnetic effects, but takes advantage of the coherent helical motion of bound electrons excited by ultra-short circularly polarized light. It results in an ultrafast chiral response and the efficient excitation of a macroscopic chiral density in an initially isotropic ensemble of randomly oriented chiral molecules. We probe this excitation using linearly polarized laser pulses, without the aid of further chiral interactions. Our time-resolved study of vibronic chiral dynamics opens a way to the efficient initiation, control and monitoring of chiral chemical change in neutral molecules at the level of electrons.