ABSTRACT
We identify and explain signatures of ongoing single-electron nonadiabatic dynamics in the high-order harmonic generation (HHG) spectrum of H+ 2. We establish the necessary laser parameter criteria for the modulation of the highest energy section of the HHG spectrum by suppressed ionisation due to transient electron localisation. This minimum is also shown to enable the emergence of an unusually complex interference structure at the highest energies of the spectrum caused by the breaking of inversion symmetry during sequential recombination events of the electron wavepacket. By inspecting the time-domain structure of the emitted radiation, we identify the role of transient electron localisation in modulating the amplitudes of individual peaks within the attosecond pulse train. Finally, an analysis of the phase mismatch accumulated within this highly structured region of HHG is performed, showing qualitative differences in coherence lengths present in different regions of the spectrum.
Acknowledgments
The authors acknowledge Carlos Hernandez-Garcia for discussions.
Disclosure statement
No potential conflict of interest was reported by the authors.