Producing keV photoelectrons from one-dimensional stretched H2+ by near-infrared intense chirped laser fields

We theoretically present a method for producing keV high-order above-threshold ionization (HATI) electrons from one-dimensional stretched H2+ in near-infrared (NIR) intense chirped laser fields by solving the time-dependent Schrödinger equation in momentum space. We find that the photoelectron energy can only be extended to 18U_p if the stretched H2+ is driven by a chirp-free laser pulse, with U_p being the ponderomotive energy. However, the cutoff position of the HATI plateau sensitively depends on the chirp rate, intensity and wavelength of laser pulses and the highest photoelectron energy can reach up to 46U_p (i.e., 2.577 keV) when the stretched H2+ is exposed to NIR intense chirped laser fields. Based on the classical analysis method, we confirm that the dramatic extension of photoelectron energy can be attributed to the well-known fact that the released electron from one proton (i.e., A or B) is elastically scattered by the neighboring proton (i.e., B or A). This work demonstrates the possibility for producing keV photoelectrons using table-top NIR intense chirped laser fields.