Influence of Femtosecond Laser Parameters on Autler-Townes Splitting of Three-Level Ladder Molecules

We theoretically investigate the Autler-Townes (AT) splitting in the photoelectron spectra of three-level ladder K₂ molecule driven by a pump-probe pulse via employing the timedependent wave packet approach. The dependence of AT splitting on two laser intensities and wavelengths are studied in detail. We firstly quantify these effects on peak shift and AT separation. The photoelectron spectra show double splitting with symmetric profiles, but with asymmetric profiles when the wavelength is changed. The magnitude of AT splitting increases with the pump laser intensity, but does not vary with probe intensity. The shifts of the absorption peaks and the splitting between AT doublet are predicted by using an analytical fitting function when the intensity/wavelength of one of the two fields is changed. These novel results are of importance for the molecular spectroscopy and may further stimulate the first principles theoretical studies analytically.