We apply ultrafast spectroscopy to ionize molecules to states that explode into fragments with Coulombic trajectories. Nuclear motion is ‘frozen’ on the timescale of the measurement, allowing structures to be established from the relative fragment momenta.
Photochemical Molecular Movies
By combining Coulomb explosion imaging mass spectrometry (CEI-MS) with optical pump-probe techniques, we measure photochemistry over the natural sub-picosecond timescales at which bonds break and form.
Potential Energy Surface Mapping
Measuring molecular geometries simultaneously with photochemistry allows reaction dynamics to be mapped to particular electronic states, enabling investigation of the underlying potential energy surfaces that define chemical behaviour.
Stigmatic Imaging Mass Spectrometry
Defocused laser pulses are used to simultaneously image large (cm-scale) surface areas. The resulting fragments are imaged in sequence based on their mass-to-charge ratios, enabling the distributions of particular molecules to be rapidly identified.
XFEL Inner-shell Spectroscopy
We frequently conduct research at X-ray free electron lasers. X-rays resonate with atomic core orbitals, resulting in significant ionization through the Auger-Meitner effect. This enables simultaneous Coulomb explosion imaging and photoelectron spectroscopy.
Mass Spectrometry Development
Our laboratory continually develops new methodologies to generate, manipulate, and detect ions. We particularly focus on methods to correlate ions measured by active-pixel sensors, in order to enable high-resolution CEI-MS.
Experiments in the Burt group can broadly be classified as physical and analytical chemistry. We apply ion imaging mass spectrometry and ultrafast spectroscopy to study molecular structures and reaction dynamics, and also develop more wide-ranging applications including surface imaging. The principal technique we use is laser-induced Coulomb explosion imaging mass spectrometry (CEI-MS), where a tabletop amplified femtosecond laser is used to strip away multiple valence electrons from a target molecule. The molecule then explodes, and its fragments are subsequently imaged, a process akin to taking a 'snapshot' of the molecular geometry at the point of ionization. See the following video from former group postdoc James Pickering for an explanation of this process and how it can be used experimentally:
