Abstract
All attosecond time-resolved measurements have so far relied on the use of intense near-infrared laser pulses. In particular, attosecond streaking, laser-induced electron diffraction and high-harmonic generation all make use of non-perturbative light–matter interactions. Remarkably, the effect of the strong laser field on the studied sample has often been neglected in previous studies. Here we use high-harmonic spectroscopy to measure laser-induced modifications of the electronic structure of molecules. We study high-harmonic spectra of spatially oriented CH3F and CH3Br as generic examples of polar polyatomic molecules. We accurately measure intensity ratios of even and odd-harmonic orders, and of the emission from aligned and unaligned molecules. We show that these robust observables reveal a substantial modification of the molecular electronic structure by the external laser field. Our insights offer new challenges and opportunities for a range of emerging strong-field attosecond spectroscopies.
Highlights
All attosecond time-resolved measurements have so far relied on the use of intense near-infrared laser pulses
We show how a strong laser field modifies the electronic structure of molecules and how to measure it
We introduce a theory that accounts for the influence of the laser field on the electronic structure of the target molecule in all three steps of highharmonic generation
Summary
All attosecond time-resolved measurements have so far relied on the use of intense near-infrared laser pulses. We accurately measure intensity ratios of even and odd-harmonic orders, and of the emission from aligned and unaligned molecules We show that these robust observables reveal a substantial modification of the molecular electronic structure by the external laser field. This field could be expected to dynamically modify the electronic structure of the target. The laser field is found to lift the degeneracy of the electronic ground state of the molecular cation (of E-symmetry in the C3v point group) and to reshape the structure of its two wave-function components This laser-induced modification of the electronic structure of the molecules is verified experimentally by accurately measuring high-harmonic spectra of aligned and oriented molecules. We show that the observables of our experiment distinguish between different sets of linear combinations of a degenerate electronic state, which is impossible in the absence of an external field
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
