Light-Induced Persistent Electronic Chirality in Achiral Molecules Probed with Time-Resolved Electronic Circular Dichroism Spectroscopy.

Chiral systems exhibit unique properties traditionally linked to their asymmetric spatial arrangement. Recently, multiple laser pulses were shown to induce purely electronic chiral states without altering the nuclear configuration. Here, we propose and numerically demonstrate a simpler realization of light-induced electronic chirality that is long-lived and occurs well before the onset of nuclear motion and decoherence. A single monochromatic circularly polarized laser pulse is shown to induce electronic chiral currents in an oriented achiral molecule. Using state-of-the-art ab initio theory, we analyze this effect and relate the chiral currents to induced magnetic dipole moments, detectable via attosecond time-resolved electronic circular dichroism (TR-ECD) spectroscopy, also known as transient absorption ECD. The resulting chiral electronic wavepacket oscillates rapidly in handedness at harmonics of the pump laser's carrier frequency, and the currents persist after the pulse ends. We establish a chiral molecular-current analogue to high harmonic generation and demonstrate attosecond transient chirality control with potential impact on spintronics and reaction dynamics.