Angle-resolved (AR) RABBIT measurements offer a high information content measurement scheme, due to the presence of multiple, interfering, ionization channels combined with a phase-sensitive observable in the form of angle and time-resolved photoelectron interferograms. In order to explore the characteristics and potentials of AR-RABBIT, a perturbative 2-photon model is developed; based on this model, example AR-RABBIT results are computed for model and real systems, for a range of RABBIT schemes. These results indicate some of the phenomena to be expected in AR-RABBIT measurements, and suggest various applications of the technique in photoionization metrology.
Paul Hockett 2017 J. Phys. B: At. Mol. Opt. Phys.50 154002
aA. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA
bNational Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
cDepartment of Physics, University of Ottawa, ON K1N 6N5 Canada
dDepartment of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
• Time-resolved photoelectron angular distributions around conical intersections are studied.
• Ab initio multiple spawning method is applied to obtain wavepacket densities.
• Geometry and energy dependent photoelectron matrix elements are employed.
• Molecular and laboratory photoelectron angular distributions are used to illustrate the non-adiabatic dynamics.
• Photoelectron spectra are compared with measured values.
We report results from a novel fully ab initio method for simulating the time-resolved photoelectron angular distributions around conical intersections in CS2. The technique employs wavepacket densities obtained with the multiple spawning method in conjunction with geometry- and energy-dependent photoionization matrix elements. The robust agreement of the calculated molecular-frame photoelectron angular distributions with measured values for CS2 demonstrates that this approach can successfully illuminate, and disentangle, the underlying coupled nuclear and electronic dynamics around conical intersections in polyatomic molecules.
ePSproc provides codes for post-processing results from ePolyScat (ePS), a suite of codes for the calculation of quantum scattering problems, developed and released by Luchesse & co-workers (Gianturco et al. 1994)(Natalense and Lucchese 1999)(R. R. Lucchese and Gianturco 2016). ePS is a powerful computational engine for solving scattering problems, but its inherent complexity, combined with additional post-processing requirements, ranging from simple visualizations to more complex processing involving further calculations based on ePS outputs, present a significant barrier to use for most researchers. ePSproc aims to lower this barrier by providing a range of functions for reading, processing and plotting outputs from ePS. Since ePS calculations are currently finding multiple applications in AMO physics (see below), ePSproc is expected to have significant reuse potential in the community, both as a basic tool-set for researchers beginning to use ePS, and as a more advanced post-processing suite for those already using ePS. ePSproc is currently written for Matlab/Octave, and distributed via Github: https://github.com/phockett/ePSproc.
Originally presented at ITAMP’s (Institute for Theoretical, Atomic and Molecular and Optical Physics, part of the Harvard-Smithsonian Center for Astrophysics) workshop on Ultrafast atomic and molecular physics with cutting-edge light sources: New opportunities and challenges, back in Nov. 2013.
A snippet from today – playing around with continuum wavefunctions for photoionization & electron scattering. The image shows electron wavefunctions for scattering from CO at a few different electron energies (10, 12 and 14 eV).