Theme 1 colloquium: Ultrafast Investigations of Photochemical Dynamics

Tuesday 7 May 2024, 2 pm

Novel Benchtop NMR Methodologies: Heteronuclear Hyperpolarization and Relaxometry of Molecules at Natural Isotopic Abundance

Laser sources facilitate a wide range of experimental strategies for interrogating the complex photochemistry operating in the excited states of polyatomic molecules. Measurements may be broadly separated into frequency- and time-resolved variants, with a combination of different approaches (with different associated observables) being required to reveal a complete mechanistic picture. In the former category, quantum state-resolved information may often be obtained using narrow linewidth lasers. This provides detailed information relating to the starting point on the photochemical reaction coordinate (via the absorption spectrum) and the asymptotic endpoints (i.e. the photoproducts). Direct observation of the intermediate pathways connecting these two limits is frequently not possible, however, due to the inherently long temporal duration of the laser pulses relative to the typical timescales of intramolecular energy redistribution dynamics. 

It is therefore desirable to obtain complementary information that monitors real-time evolution along the reaction coordinate as excited state population traverses the potential energy landscape. This may be achieved in time-resolved pump-probe experiments conducted using ultrafast (i.e. sub-picosecond) laser pulses. Developing detailed insight into such processes is vital in understanding, for example, the photo-protection provided by chemical systems such as melanin and the photo-stability exhibited by DNA. A particular aim is to move beyond traditional structure-function relationships that often underpin mechanistic chemical interpretation and build the case for considering a more complete structure-dynamics-function picture. This will be illustrated for several exemplar systems using both the time-resolved photoelectron imaging (TRPEI) and transient absorption spectroscopy (TAS) techniques.

After the colloquium we'll have some sweets! (bring your own cup for coffee, etc.)

Contact: Dr. Daniel Horke, d.horke [at] science.ru.nl (d[dot]horke[at]science[dot]ru[dot]nl)

When
Tuesday 7 May 2024, 2 pm
Speaker
prof. Dave Townsend - Heriot Watt University Edinburgh, UK
Locations
Huygens building, HG00.304