Recent advances in hollow-core photonic crystal fibre technology now permit widely tuneable generation of femtosecond light pulses in the ultraviolet spectral region. This approach will be combined with time-resolved photoelectron spectroscopy to study the ultrafast dynamics of non-radiative energy redistribution within the excited states of small, biologically relevant molecules.
The use of ultrafast femtosecond lasers with pulse durations comparable to the timescales of molecular motion has become widely employed for studying real-time energy redistribution dynamics following ultraviolet (UV) absorption. Investigating such processes using pump-probe spectroscopy is important for understanding photo-protection mechanisms that take place in, for example, DNA and the melanin pigmentation system, serving to protect the body from the potentially damaging effects of UV light. They are also of critical relevance for many other classes of molecular system, including photochromic polymers, light harvesting complexes, sunscreens, photodynamic therapy drugs and molecules relevant to atmospheric/interstellar photochemistry.
Generating femtosecond pulses in the deep UV region by conventional means (using thin birefringent crystals) is often extremely inefficient, and this places restrictions on the feasibility and scope of many studies. The rapidly emerging field of hollow-core photonic crystal fibres (HC-PCFs) offers greatly improved (100-1000x) gains in UV generation efficiency. HC-PCFs also provide a light source that is more easily tuned over a wide range of UV wavelengths, and potentially provides much improved experimental time resolution. This opens up exciting new possibilities within the field of ultrafast molecular dynamics.
This project will combine HC-PCF sources with state-of-the art time-resolved photoelectron imaging spectroscopy to study non-radiative energy redistribution in series of systematically substituted molecules. The systems chosen will provide analogues of the chromophores (i.e. the light absorbing centres) found in larger molecules of biological significance. A key focus will be on the interplay between molecular structure, dynamical timescales and photochemical function. The project is well suited to those with an interest in non-linear optics, lasers and spectroscopy. Some software development for data acquisition/analysis will be required and there will be opportunities to gain proficiency with commercial quantum chemistry computational platforms such as Gaussian.
The annual stipend will be approx. £14,777 and full fees will be paid, for 3.5 years.