Effect of nuclear motion on high-order-harmonic generation of H2+ in intense ultrashort laser pulses

Abstract

High-order-harmonic generation is investigated for H2+ and D2+ with and without a Born-Oppenheimer approximation by a numerical solution of a full dimensional electronic time-dependent Schrödinger equation under four-cycle intense laser pulses of 800 nm wavelength and I=4, 5, 7, and 10×1014 W/cm2 intensities. For most harmonic orders, the intensity obtained for D2+ is higher than that for H2+, and the yield difference increases as the harmonic order increases. Only at some low harmonic orders, H2+ generates more intense harmonics compared to D2+. The results show that nuclear motion, ionization probability, and system dimensionality must be simultaneously taken into account to properly explain the isotopic effects on high-order-harmonic generation and to justify experimental observations. © 2014 American Physical Society.