近日，法国里昂大学光谱学研究所的F. Lépine&V. Loriot及其研究团队取得一项新进展。经过不懈努力，他们实现分子中二维电荷分布的阿秒计量。相关研究成果已于2024年2月23日在国际知名学术期刊《自然—物理学》上发表。

据悉，光电离作为一种半散射过程，并非瞬间完成。一般来说，光电离的时间延迟大约在几十阿秒左右。当从单个原子扩展到纳米物体时，由于光电子在更大的距离上进行散射，科学家预期这种延迟会有所增加。

该研究团队的研究结果表明，当对比三维分子与平面分子时，人们的直觉并不准确。利用阿秒干涉测量法，研究人员发现，二维碳基分子的时间延迟远低于三维碳基分子的时间延迟。这些测量得到的时间延迟反映了残余分子阳离子中二维空穴的空间分布特征，使得研究人员能够以埃米的精度确定其尺寸。此研究揭示了光电离延迟取决于所产生的空穴的对称性和形状，研究人员通过确定二维分子测量延迟中的四极贡献进一步证明了这一点。

附：英文原文

Title: Attosecond metrology of the two-dimensional charge distribution in molecules

Author: Loriot, V., Boyer, A., Nandi, S., Gonzlez-Collado, C. M., Plsiat, E., Marciniak, A., Garcia, C. L., Hu, Y., Lara-Astiaso, M., Palacios, A., Decleva, P., Martn, F., Lépine, F.

Issue&Volume: 2024-02-23

Abstract: Photoionization as a half-scattering process is not instantaneous. Usually, time delays in photoionization are on the order of tens of attoseconds. In going from a single atom to a nano-object, one can expect the delay to increase, since the photoelectron scatters over a larger distance. Here we show that this intuition is not correct when comparing three-dimensional and planar molecules. Using attosecond interferometry, we find that the time delays in two-dimensional (2D) carbon-based molecules can be significantly shorter than those of three-dimensional counterparts. The measured time delay carries the signature of the spatial distribution of the 2D hole created in the residual molecular cation, allowing us to obtain its dimensions with angstrom accuracy. Our results demonstrate that the photoionization delay depends on the symmetry and shape of the created hole, as we show by identifying a quadrupole contribution in the measured delay of 2D molecules.

DOI: 10.1038/s41567-024-02406-2

Source: https://www.nature.com/articles/s41567-024-02406-2