Attosecond ionization delays in molecules are novel probes of electron correlations in the molecular environment. Relativistic effects in molecules due to spin-orbit coupling are known to figure in structural chemistry and can affect chemical reactions, but the anisotropic potential and congested spectra make it difficult to disentangle contributions from neighboring spin-orbit states. Here, we measure the energy-dependent relative delays between the photoelectron wave packets from two valence spin-orbit states of methyl iodide. We observe substantial modulations in the time-delay photoelectron spectrum from 5–20 eV, a region that includes both spin-orbit and two-electron states. Our calculations show this complex delay spectrum is connected to the interplay between relativistic spin-orbit activated interchannel coupling and spin-flip transitions, as well as the high density of two-electron transitions. This work establishes spin-orbit resolved time delay measurements as a viable tool to probe electronic correlations in molecules and highlights the significant role of relativistic effects on molecular time delay measurements.

Close

PrevNext

View figure in article

• Atomic & molecular processes in external fields
• Photoemission
• Relativistic & quantum electrodynamic effects in atoms, molecules,& ions
• Single- and few-photon ionization & excitation
• Ultrafast phenomena
• Atoms
• Molecules
• Photoionization of molecules