Speaker
Description
We present results of calculations of attosecond delays [1] in molecules containing heavy atoms and a methodology for inclusion of relativistic effects.
We focus on streaking delays in iodoalkanes at high photon energies around 100 eV, which probe the iodine 4d shell. In collaboration with the experimental group of R. Kienberger of TU Munich our ultimate aim is to understand streaking from such molecules deposited on surfaces. As a first step we focus on the study of an isolated iodine atom and the CH$_3$I molecule in the laboratory and molecular frames. Our goal is to accurately describe the effect of the iodine “giant dipole resonance” [2,3] on time-delays in both atomic and molecular environments.
To do this, we use the UKRmol+ suite [4] employing the R-matrix scheme, which is able to calculate a number of photoionization observables including the 1-photon Wigner and 2-photon RABITT delays. Within the suite our photoionization models are able to clearly separate collective effects from mean field ones. Our work also highlights that in the case of the polar CH$_3$I molecule in the molecular frame it is crucial to properly include the so-called “dipole-laser dressing” [6] in both the neutral and the ionized molecule.
We employ the newly implemented functionality of UKRmol+ to use “effective core potentials” [5] to include scalar relativistic effects originating in the inactive core electrons. To describe the scalar and spin-orbit relativistic effects for the active electrons we are utilizing the Breit-Pauli Hamiltonian in combination with the “Distorted Wave Born” approach of arbitrary order. We have successfully implemented this approach in the R-matrix scheme for model 1-electron problems and are working on the implementation in the multi-electron UKRmol+ suite.
[1] Pazourek, R., et al. (2015). Reviews of Modern Physics, 87(3) 765-802.
[2] Biswas, S., et al. (2020). Nature Physics, 16(7) 778-783.
[3] Lindle, D. W., et al. (1984). Physical Review A, 30(1) 239.
[4] Mašı́n, Z., et al. (2020). Computer Physics Communications, 249, 107092.
[5] Reiher, M., & Wolf, A. (2015). John Wiley & Sons.
[6] Benda, J., & Mašı́n, Z. (2024). Physical Review A, 109(1) 013106.
[7] Scott, N. S., & Burke, P. G. (1980). Journal of Physics B, 13(21) 4299.
