“First” Paper from Nottingham

Our first paper (thus far) on femtosecond ring-opening dynamics in a model cyclic disulfide is in-press at Chemical Physics Letters (https://doi.org/10.1016/j.cplett.2025.142095).

Disulfide bonds are the chemical staples of biology that define tertiary structures of proteins. They are extremely sensitive to oxidative and photochemical stress, and we wanted to understand the initial response to these stresses and what fundamental mechanisms exist that would lead to such sensitive bonds playing this critical role in biology.

In this paper, we show that UV light triggers a rapid breaking of the sulfur-sulfur bond and launches a nuclear wavepacket that we observe in the time-dependent yield of sulfur dications generated using a strong-field ionisation probe. This oscillation has a period of ~400 fs and it persists beyond the measurement window of our experiment (1.2 ps).

Our findings are validated by comparison with quantum molecular dynamics simulation, and in agreement with a prior experimental study. Our simulated trajectories are also used to calculate how the first three ionisation energies change with the evolving nuclear geometry.

These results are a prelude to an upcoming publication in which we will show direct observation of the nuclear dynamics through coincident momentum imaging.

Many thanks to everyone on the team, and to the Artemis facility at the Central Laser Facility for the access and technical expertise. Particularly, I’d like to thank the Vallance Group (vallance.chem.ox.ac.uk) for being excellent mentors, colleagues and friends over the last three years, as well as Matt Robinson (now at EuXFEL) for matching my enthusiasm for this idea when we met at the Faraday discussions poster session. I’m looking forward to seeing where this collaboration takes us in the future.