Determining Molecular Chirality with Femtosecond Lasers
First Supervisor : Dr Jason Greenwood (j.greenwood@qub.ac.uk)
Second Supervisor : Prof. Ian Williams
Project Background and Description :
A molecule is chiral, having left and right handed types, if one type cannot be rotated so that it is
superposed on the other. These molecules have very similar chemical and physical properties such as
having the same infrared(IR) and nuclear magnetic resonance (NMR) spectra. However, left and right
handed chiral molecules often taste, smell and interact with biological systems very differently. Most
drugs are chiral compounds and often only one type is the active agent while the other can be
poisonous. This was dramatically demonstrated in the 1950s and 1960s when thalidomide was given
to pregnant woman to cure morning sickness but resulted in terrible birth defects. The reason for these
catastrophic consequences is that the molecules of life are homochiral, for instance nearly all amino
acids are left-handed while sugars are right-handed. The reasons for the existence of biological
homochirality and if it is a pre-requisite for life remain a subject of intense debate.
Chirality therefore has massive implications for the development of drugs and understanding life
itself. However, present methods for identifying the different types of a chiral molecule are not very
sensitive and mainly rely on the small differences in light absorption depending on whether the light
is left or right circularly polarized. For this project a new conceptual approach based on asymmetry in
the angular distribution of electrons emitted from photoionization of chiral molecules will be
investigated 1,2,3. This phenomenon is several orders of greater in magnitude than current techniques
and could provide a highly sensitive measurements of chirality in chemical samples. A prototype
instrument is currently in development in our lab which uses femtosecond laser pulses to ionise the
molecules. This device will be used for both fundamental studies and applications, such as to probe
ultrafast changes in the structure of molecular motors and measuring the handedness of trace amounts
of chiral compounds.
Skills : To realise these objectives you will be trained in a range of state-of-the-art techniques. These
include high power femtosecond laser technology, mass spectrometry, ultra-high vacuum techniques,
computer controlled data acquisition, and ion optics simulations. This would suit someone who is
prepared for day-to-day hands on operation and development of the equipment, and acquiring and
analysing data from the experiment. There will also be collaboration with the Atomistic Simulation
Centre who will be modelling the laser-molecule interaction to produce results with which to compare
to our experimental work.
References:
1. L. Nahon et al., Journal of Electron Spectroscopy and Related Phenomena, 204, 322(2015)
www.sciencedirect.com/science/article/pii/S0368204815000766
2. C. Lux et al., Angewande Chemie Int. Ed. 51, 1 (2012)
onlinelibrary.wiley.com/doi/10.1002/anie.201109035/full
3. M. Fanood et al., Nature Communications, 6, 7511 (2015)
www.nature.com/ncomms/2015/150624/ncomms8511/full/ncomms8511.html
Jason Greenwood
Current PhD Students
Jordan Miles – DEL, ends Sept 2016
Simone De Camillis – Leverhulme Trust, ends Sept 2016
Current Funding
Grant Title
A Novel LIAD Source for the Enhanced Study
of Molecular Dynamics
Ultrafast Intra-Molecular Electron Dynamics
High Sensitivity Enantiomer Analysis via
Stereo Photoelectron Circular Dichroism
Funding Body
Leverhulme Trust
Grant No.
RPG-2012-735
PI
Ownership
100%
Duration
1/4/13 – 30/9/16
Value
£71k
Engineering and Physical
Sciences Research Council
Engineering and Physical
Sciences Research Council
EP/M001644/1
PI
100%
1/1/15 – 30/6/16
£101k
PI
100%
1/4/16 – 30/9/18
(£385k)
pending