Photons have fixed spin and unbounded orbital angular momentum (OAM). While the former is manifested in the polarization of light, the latter corresponds to the spatial phase distribution of its wavefront¹. The distinctive way in which the photon spin dictates the electron motion upon light–matter interaction is the basis for numerous well-established spectroscopies. By contrast, imprinting OAM on a matter wave, specifically on a propagating electron, is generally considered very challenging and the anticipated effect undetectable². In refs. ^3,4, the authors provided evidence of OAM-dependent absorption of light by a bound electron. Here, we seek to observe an OAM-dependent dichroic photoelectric effect, using a sample of He atoms. Surprisingly, we find that the OAM of an optical field can be imprinted coherently onto a propagating electron wave. Our results reveal new aspects of light–matter interaction and point to a new kind of single-photon electron spectroscopy.

光子具有固定的自旋和无界的轨道角动量（OAM）。前者表现为光的偏振，而后者对应于其波阵面¹的空间相位分布。光子自旋决定光与物质相互作用时电子运动的独特方式是许多公认的光谱学的基础。相比之下，将OAM印在物质波上，特别是在正在传播的电子上，通常被认为是非常具有挑战性的，预期的效果无法检测²。在裁判。^3,4，作者提供了结合电子对OAM依赖的光吸收的证据。在这里，我们尝试使用He原子样本观察OAM依赖的二向色光电效应。令人惊讶地，我们发现光场的OAM可以被连贯地压印在传播的电子波上。我们的结果揭示了光与物质相互作用的新方面，并指出了一种新型的单光子电子光谱。