Update August 2017 – this article is now published in PRL, under the alternative title Molecular Frame Reconstruction Using Time-Domain Photoionization Interferometry.
Phys. Rev. Lett. 119, 083401 (2017), DOI: 10.1103/PhysRevLett.119.083401
(Feb 2017) New manuscript on the arxiv:
Photoionization of molecular species is, essentially, a multi-path interferometer with both experimentally controllable and intrinsic molecular characteristics. In this work, XUV photoionization of impulsively aligned molecular targets (N2) is used to provide a time-domain route to “complete” photoionization experiments, in which the rotational wavepacket controls the geometric part of the photoionization interferometer. The data obtained is sufficient to determine the magnitudes and phases of the ionization matrix elements for all observed channels, and to reconstruct molecular frame interferograms from lab frame measurements. In principle this methodology provides a time-domain route to complete photoionization experiments, and the molecular frame, which is generally applicable to any molecule (no prerequisites), for all energies and ionization channels.
Supplementary material (theory, data and code) available at DOI: 10.6084/m9.figshare.4480349.
Our ongoing work on the calculation of time-dependent wavepackets and observables in photoionization is now collected in an OSF project (DOI: 10.17605/OSF.IO/RJMPD). Aspects of this work have previously been published, but much of the detail and methodology underlying the calculations has remained sitting on our computers. As part of our Open Science Initiative, we’re letting this data go free! Head over to the OSF project “Time-dependent Wavepackets and Photoionization – CS2” for more.
Figure shows TRPADs results (a) Calculated TRPADs (0.7eV) (b), (c) Comparison with expt. TRPADs (discrete times).
A brief glimpse at some recent work – scattering calculations for NO2. The figure shows the molecular-frame photoelectron flux for light-matter interaction of various geometries (linearly polarized light), hence scattering into different continua. The inset shows the ionizing orbital and molecular geometry.
This is just a snippet from an ongoing effort to explore quantum coherence in molecular ionization.
A snippet from some theory work in progress on time delays in molecular photoionization. The image below shows the energy and angle-resolved cross-section (surface topography) and Wigner delay (colour map) over a 40 eV range for CO. Unsurprisingly, for a molecular scatterer (albeit a simple heteronuclear diatomic) the map is quite complicated! Here the delays range from -200 to +200 attoseconds, and peak at the Carbon end of the molecule.
More on this soon… the paper is almost ready…
UPDATE Dec. 2015
Now on the arXiv:
P. Hockett, E. Frumker, D.M. Villeneuve, P.B. Corkum
arXiv 1512.03788, 2015
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).
A beautiful bit of quantum mechanics!
And hats off to R. Luchesse (Texas A&M) for distributing ePolyScat, which was used for the underlying computation.