title: Origin of double-line structure in nonsequential double ionization by few-cycle laser pulses.
abstract: We investigate nonsequential double ionization (NSDI) of molecules by few-cycle laser pulses at the laser intensity of 1.2-1.5 × 10(14) W/cm(2) using the classical ensemble model. The same double-line structure as the lower intensity (1.0 × 10(14) W/cm(2)) is also observed in the correlated electron momentum spectra for 1.2-1.4 × 10(14) W/cm(2). However, in contrast to the lower intensity where NSDI proceeds only through the recollision-induced double excitation with subsequent ionization (RDESI) mechanism, here, the recollision-induced excitation with subsequent ionization (RESI) mechanism has a more significant contribution to NSDI. This indicates that RDESI is not necessary for the formation of the double-line structure and RESI can give rise to the same type of structure independently. Furthermore, we explore the ultrafast dynamics underlying the formation of the double-line structure in RESI.
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Huang
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
authors.forename: Mingmin
authors.initials: M
authors.lastname: Zhong
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
authors.forename: Zhengmao
authors.initials: Z
authors.lastname: Wu