Sven-Joachim Paul | Searcharxiv

arXiv2026

Photoemission study of Iodoalkanes

Core level atomic photoionization is influenced by the molecular environment of the emitting atom. To probe this influence we used extreme ultraviolet (XUV) radiation to measure the I$\left(4d\to\varepsilon f \right)$ photoemission of four iodine substituted alkanes in the range from 60 eV to 160 eV photon energy. Using two detection angles relative to light polarization allowed us to extract and compare the asymmetry parameter of the investigated compounds. These results are in agreement with theory by Pi and Landsman (L.-W. Pi and A. Landsman, Attosecond time delay in photoionization of noble-gas and halogen atoms, Applied Sciences 8, 322 (2018)) and previous experiments by Olney et al. (T. N. Olney, G. Cooper, and C. Brion, Quantitative studies of the photoabsorption (4.5-488 ev) and photoionization (9-59.5 ev) of methyl iodide using dipole electron impact techniques, Chemical Physics 232, 211 (1998)) for iodomethane. 2-iodopropane behaves nearly identical to iodomethane, while for iodoethane and 1-iodopropane we find a distinct and consistent, energy dependant difference most prominent at around 130 eV photon energy. This further proves the influence of the chemical environment on core level photoionization. Due to the sensitivity on the exact positions of the carbon atoms and the energy dependence we hypothesise this difference is caused by intramolecular scattering of the outgoing photoelectron wave packet, causing changes in the angular distribution.

physics.atom-ph↗

arXiv2025

Photoemission Chronoscopy of the Iodoalkanes

Time delays in photoemission are on the order of attoseconds and have been experimentally determined in atoms, molecules and solids. Their magnitude and energy dependence are expected to yield fundamental insights into the properties of the systems in which they're measured. In a recent study Biswas \textsl{et al.} (Biswas, S., Förg, B., Ortmann, L. et al. Probing molecular environment through photoemission delays. Nat. Phys. 16, 778-783 (2020)) determined the absolute photoemission time of the I$4d$ level in iodoethane via attosecond streaking spectroscopy, finding the presence of a functional group to increase the photoemission time delay, suggesting a correlation between the size of the functional group and time delay based on a semi-classical calculation. Here we experimentally study the dependence of the I$4d$ photoemission time on the functional group in the iodoalkanes from iodomethane up to 2-iodobutane at three photon energies across the giant resonance in the I$4d\to\varepsilon f$ photoemission channel, finding that the presence alone of a functional group does not necessarily increase the photoemission delay, and that overall no clear correlation between its size and the photoemission time delay can be established.

physics.chem-ph↗