Dissociative multi-ionization of N2O molecules in strong femtosecond laser field

Abstract

Multi-ionization and subsequent Coulomb explosion (CE) of the N2O molecule irradiated by linearly polarized 800 nm laser field is investigated by a reaction microscope, where a number of CE channels of N2Oq+ with q{less than or equal to}5 for two-body fragmentation and q{less than or equal to}8 for three-body fragmentation were observed. For two-body CE, by analyzing the internuclear separations extracted from kinetic energy releases (KERs), dissociation branching fractions, and laser intensity dependence, interestingly we found that fragmentation N2O5+→N3++NO2+ is produced directly from dissociating N2O3+ via non-sequential stairstep ionization whereas most of others result from the sequential stairstep ionization. For three-body CE, 25 fragmentation channels of N2Oq+ (q = 3-8) are distinguished in present charge-encoded multi-photoion coincidence plot and the concerted fragmentation mechanism is nominated in a typical Dalitz plot. With the help of the numerical computation with the measured KERs and momentum correlation angles, the geometric structures of molecular ions prior to fragmentation are reconstructed, which display the bending motion and simultaneous two-bond stretching before the CE. Increasing of bond length for high charged N2Oq+ indicates the dominating stairstep ionization in three-body fragmentation.

High-resolution multi-mode electron and ion imaging spectrometer at SXFEL

“…We have also established a COLTRIMS [14,30,31] setup at Shanghai soft x-ray free-electron laser (SXFEL). This setup is capable of operating in momentum imaging mode, with an electron energy detection range of 108 eV and a resolution of electron and ion momentum better than 0.11 a.u, measured from a single ionization experiment of oxygen molecules in an infrared (IR) femtosecond laser field.…”