Head of Physical Chemistry Section
|Helen Fielding is Professor of Physical Chemistry and Head of Physical Chemistry and Chemical Physics. Her research is focused on the spectroscopy and ultrafast dynamics of excited states of molecules and protein chromophores in the gas-phase and in solution. She has a long-standing collaboration with Professor Graham Worth and collaborates with several other colleagues at UCL (Professor Jim Anderson, Professor Helen Hailes, Professor Charles Marson, Dr Mike Porter, Professor Geoff Thornton, Professor John Ward) and externally (Professor Mike Robb, Imperial; Professor Georg Held, Diamond Light Source). Before coming to UCL in 2003, she worked at King’s College London (Lecturer 1994-1997; Reader 1997-2002; Professor 2002-2003). Prior to this, she was a postdoctoral research fellow at the University of Amsterdam, working with Professors Ben van Linden van den Heuvell and Wim van der Zande (1993-1994), a scientist at the National Physical Laboratory (1992) and a DPhil student at Cambridge then Oxford, working with Professor Tim Softley (1989-1992).|
|Summary of research group|
|Professor Fielding’s group is recognized internationally for their original work in the field of spectroscopy and dynamics of excited state of molecules. During the last 15 years, they have designed and built four separate experiments employing photoelectron spectroscopy to study small neutral molecules in the gas-phase, large molecular anions in the gas-phase, molecules on surfaces and, most recently, organic chromophores in solution. They have developed collaborations with synthetic organic chemists to create molecules with specific molecular and electronic structures. They also have expertise in electronic structure theory to support the interpretation of her experimental work but maintain an important and long-standing collaboration with Professor Graham Worth at UCL, who carries out complementary high-level electronic structure and dynamics calculations.|
Highlights from their work on femtosecond dynamics of isolated molecules
in the gas-phase include the discovery that ultrafast intersystem crossing
competes with internal conversion in the prototypical organic molecule benzene
(PCCP, 12, 15607, 2010) and unravelling the role of the 3s Rydberg component of dissociative states in the non-radiative decay of hetero-aromatic molecules (PCCP 14, 9942, 2012; PCCP 16, 3122 2014; PCCP 17, 16270, 2015; Chem. Phys. Lett. 2017). Recently, they discovered an entirely new non-radiative decay pathway in pyrrole dimers and believe that this low-energy, photo-induced electron-transfer process is likely to play a key role in the electronic relaxation of biological and technological systems containing the pyrrole building block and other heteroaromatic molecular motifs (Nat. Commun. 7, 11357, 2016).
Highlights from their work on biological chromophore anions include
showing that the first electronically excited state of the isolated green
fluorescent protein chromophore anion in the gas-phase is bound with respect to
electron detachment, contradicting earlier theoretical predictions
(J. Phys. Chem. A 116, 7943, 2012), finding that the relaxation dynamics in the gas-phase are identical to those in solution (Chem. Sci. 4, 921, 2013) and demonstrated that the redox properties of the chromophore can be controlled by moving the position of a hydroxy group on the chromophore or chemical substituents with electron withdrawing or electron donating character (Chem. Sci. 8, 1621, 2017; Chem. Sci. 8, 3154, 2017).
Another recent highlight is their paper on molecular motors, “Unravelling the electronic structure and dynamics of an isolated molecular rotary motor in the gas-phase” published in (Chem. Sci. 8, 6141, 2017).
|Recent highlights from the group|
Jamie Riley (PhD student, 2014-18) won 2nd prize at the 2017 Southern Universities Spectroscopy and Dynamics Groups group meeting held in September for his talk, "Exploring solvation effects on the electronic structure of phenol". His talk described the first systematic UV photoelectron spectroscopy study of phenol in aqueous solution carried out using the UK's first liquid jet photoelectron spectrometer, designed and built at UCL by Dr Bingxing Wang, a PDRA in the group.
Jana Ockova (MSci student, 2016-17) won the Lonsdale Medal for the best graduating student in the MAPS Faculty.
Alice Henley (PhD student, 2016-19) won the PCCP poster prize at the 2017 RSC Faraday Joint Interest Group Conference held in April for her poster, “Electronic structure and dynamics of conformationally-locked photoactive yellow protein chromophores”.
Jamie Tay (MSc student, 2013-14) had her work on “The effect of conjugation on the competition between internal conversion and electron detachment: a comparison between green fluorescent and red Kaede protein chromophores” published in J. Phys. Chem. Lett. 8 765, 2017.
Ciara Phillips (MSci student, 2014-15) had her work on “Controlling electron emission from the photoactive yellow protein chromophore by substitution at the coumaric acid group” published in PCCP, 18, 10329, 2016.
Conor McLaughlin (MSci student, 2015-16) had his work on “ortho and para chromophores of green fluorescent protein: controlling electron emission and internal conversion” published in Chem. Sci., 8 1621, 2017.
|Femtosecond and nanosecond laser systems, molecular beam velocity-map imaging photoelectron spectrometer for neutral molecules, electrospray-ionisation velocity-map imaging photoelectron spectrometer for anions, liquid-microjet magnetic bottle photoelectron spectrometer for liquids, UHV hemispherical photoelectron energy analyser for surfaces.|