We demonstrate an angular high-harmonic spectroscopy method to probe the spinning dynamics of a molecular rotation wave packet in real time. With the excitation of two time-delayed, polarization-skewed pump pulses, the molecular ensemble is impulsively kicked to rotate unidirectionally, which is subsequently irradiated by another delayed probe pulse for high-order harmonic generation (HHG). The spatiotemporal evolution of the molecular rotation wave packet is visualized from the time-dependent angular distributions of the HHG yields and frequency shift measured at various polarization directions and time delays of the probe pulse. The observed frequency shift in HHG is demonstrated to arise from the nonadiabatic effect induced by molecular spinning. Different from the previous spectroscopic and Coulomb explosion imaging techniques, the angular high-harmonic spectroscopy method can reveal additionally the electronic structure and multiple orbitals of the sampled molecule. All the experimental findings are well reproduced by numerical simulations. Further extension of this method would provide a powerful tool for probing complex polyatomic molecules with HHG spectroscopy.




This work was supported by the National Natural Science Foundation of China under Grants No. 11627809, No. 11874165, No. 11704137, and No. 11774109. A. T. L. and C. D. L. were partially supported by the U.S. Department of Energy under Grant No. DE-FG02-86ER13491.

Keywords and Phrases

Electronic structure; Molecular dynamics; Molecules; Optical pumping; Polarization; Spectroscopic analysis; Stereochemistry; Time delay; Wave packets

International Standard Serial Number (ISSN)

0031-9007; 1079-7114

Document Type

Article - Journal

Document Version

Final Version

File Type





© 2018 American Physical Society (APS), All rights reserved.

Publication Date

01 Oct 2018

PubMed ID


Included in

Physics Commons