Ultrafast photochemical processes in 1,2-dichloroethene measured with a universal XUV probe.

The presence of two chlorine atoms in 1,2-dichloroethene allows for isomerization around the double bond. This isomerization can lead to rich photochemistry. We present a time-resolved pump-probe photoelectron spectroscopy measurement on both the - and - isomers of 1,2-dichloroethene.

Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane.

The light-induced ultrafast switching between molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Prior work observed signatures of ultrafast molecular dynamics in both isomers upon ultraviolet excitation but could not follow the electronic relaxation all the way back to the ground state experimentally. Here we study the electronic relaxation of quadricyclane after exciting in the ultraviolet (201 nanometres) using time-resolved gas-phase extreme ultraviolet photoelectron spectroscopy combined with non-adiabatic molecular dynamics simulations.

Manipulating hydrogen atoms using permanent magnets: Characterisation of a velocity-filtering guide.

A Halbach array composed of 12 permanent magnets in a hexapole configuration is employed to deflect hydrogen atoms as they exit a Zeeman decelerator. The ability to preferentially manipulate H atoms is very useful, as there are currently very few techniques that are appropriate for purifying a beam of H atoms from precursor molecules (such as molecular hydrogen or ammonia), seed gases, and other contaminant species. The extent to which hydrogen atoms are deflected by a single Halbach array when it is tilted or shifted off the main beam axis is characterised experimentally and interpreted with the aid of a simple mathematical model.