Photoemission Chronoscopy of the Iodoalkanes

TL;DR

This study investigates how different functional groups in iodoalkanes affect the photoemission time delays, revealing no consistent correlation and challenging previous assumptions about the influence of functional group size.

Contribution

It provides the first experimental analysis of photoemission delays across various iodoalkanes, showing that functional group presence alone does not determine delay magnitude.

Findings

No clear correlation between functional group size and delay.

Functional group presence does not necessarily increase delay.

Photoemission delays vary independently of functional group size.

Abstract

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., F\"org, 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.