Investigation of thermal and collisional effects on IRMPA and IRMPD of SF6 via a combined model involving rotationally resolved coherent-incoherent interface and quasicontinuum

Abstract

A computationally simple model incorporating a rotationally resolved interfacing scheme between the regions of coherent and incoherent excitation (3 nu 3) and rotational structure in the quasicontinuum (QC) describes the total excitation and dissociation process of SF6 in an argon buffer. The effective cross section from a particular rotational sublevel of 3 nu 3 mode is obtained from the sum of Lorentzian functions of all allowed transitions to 4 nu 3 from that particular sublevel. The many resonances in the allowed transitions cause a large decrease in the bottleneck to the transition to the QC and a shift of the spectrum to the blue compared with that in our earlier model where the interface was rotationally unresolved. Using these cross sections, an effective two-level scheme demonstrates the formation of holes in the rotational distribution of molecules in the discrete levels and their subsequent disappearance at various buffer gas pressures and for different incident laser frequencies.