Ivanov, IgorNam, ChangheeKim, Kyung Taec2021-08-302021-08-301050-2947http://hdl.handle.net/1885/245925We present a study of the photoelectron spectra for the ionization process driven by counterrotating and corotating circularly polarized fundamental and odd-order harmonic fields. The main features of the spectra, such as symmetric lobed structures, are understood using simple arguments based on the strong field approximation (SFA) picture of ionization. A deviation from this picture is, most notably, the presence of the low-energy structures (LES) in the spectra. We show that the Rydberg states populated as a result of the combined absorption of the photons from the fundamental and harmonic fields are responsible for the origin of LESThis work was supported by the Institute for Basic Science under IBS-R012-D1.application/pdfen-AU© 2017 American Physical Society201710.1103/PhysRevA.95.0534012020-11-23