Dynamic Stark effect and interference photoelectron spectra of H2+

For atomic hydrogen, an interference structure has been theoretically found to appear in the photoelectron spectra induced by strong extreme ultraviolet (XUV) laser pulses [Demekhin and Cederbaum, Phys. Rev. Lett. 108, 253001 (2012)]. For molecular hydrogen ion H-2(+), our present work provides the results of the numerical simulation on its photoelectron spectra in an XUV photoionization process. The interference feature in the photoelectron spectra is investigated with respect to the dynamic Stark effect and the XUV laser parameters. The research outcome is that our numerical findings corroborate the prediction for the emergence of the modulation structures in the photoelectron spectra, similar to those already found for a hydrogen atom. For an XUV laser pulse with photon energy well above the ionization threshold of H-2(+), the dynamic Stark effect is prominently demonstrated for certain values of laser parameters such as intensity and pulse duration. The deployed one-dimensional model and the plane-wave description for the continuum states for the molecular hydrogen ion are of crucial significance in modeling the molecular system. The numerical computation is made feasible by using a hybrid algorithm. We advocate an ensemble physical picture to decipher the physical mechanism for the formation of the interference photoelectron spectra by taking into account the nuclear degree of freedom. It is anticipated that more quantitative investigations on the Stark effect concealed in the photoelectron spectra created by single XUV photons are needed plus experimental verifications.