The DynAMO (Dynamics of Atomic, Molecular and Optical) end-station on Artemis is dedicated to studies of molecular dynamics in the gas phase. DynAMO is a modular end-station comprising a source and main spectrometer chamber withthree optional molecular sources (CW gas-jet, effusive and laser desorption) and two spectroscopy techniques (dual photoelectron and photoion coincidence and photoelectron time-of-flight). The DynAMO end-station specialises in pump-probe experiments with a temporal resolution of <50fs with tuneable pump pulses from 190 to 2,000nm, and tuneable XUV probes from 15 to 80eV.
Photoelectron-photoion coincidence spectroscopy
Photoelectron-photoion coincidence spectroscopy (PEPICO) is the flagship technique of the DynAMO end-station. By using a dual velocity map imaging spectrometer, DynAMO can record all photoelectrons and photoions generated from a single laser shot. By correlating the momentum vectors of all charged particles, it is possible to filter photoelectrons to specific ion mass-to-charge ratios, and their momentum, to provide photoelectron spectra free of any background or to correlate other ions produced in the same events as the selection ion. These spectra provide unique fingerprints to identify chemical isomers and photoproducts that are produced during the photochemical reaction. Furthermore, at higher XUV photon energies the same device can be used for single photon, multiple ionisation experiments where, by correlating the momentum vectors of all ions generated, it becomes possible to track structural dynamics directly using coulomb explosion imaging.
The PEPICO system on DynAMO comprises a dual velocity-map imaging (VMI) stack with two 100mm active area delay line detectors (Roentdek Hex100). PEPICO can be combined with the effusive or CW jet molecular sources.
The PEPICO system utilises the Light Conversion laser system. We can provide pump wavelengths between 190 and 2000nm, and probe wavelengths between 15 and 80eV.
Time-of-flight photoelectron spectroscopy
Photoelectron spectroscopy provides a unique fingerprint of electronic structure of molecules. The time-of-flight (ToF) spectrometer on the Artemis DynAMO end-station is a designed to have a reduced noise floor, minimising scattered UV light typically associated with short wavelength deep-ultraviolet (DUV) optical pumps. DynAMO provides an angle resolved spectrometer with up to three electron ToF (eToF) spectrometers, two vertical and one horizontal, for simultaneous collection of perpendicular photoelectron ejection angles. These provide angular distribution information, and the ability to focus on separate kinetic energy regions simultaneously.
The eToF system on DynAMO has a horizontal Kaisdorf ToF and two vertical home-built eToFs. eToFs can be combined with the effusive or CW jet molecular sources. The eToF system uses the Light Conversion 100kHz laser system. We can provide pump wavelengths between 190 and 2,000nm, and probe wavelengths between 15 and 80eV.
Selected publications:
- Mapping the Complete Reaction Path of a Complex Photochemical Reaction, Adam D. Smith, Emily M. Warne, Darren Bellshaw, Daniel A. Horke, Maria Tudorovskya, Emma Springate, Alfred J. H. Jones, Cephise Cacho, Richard T. Chapman, Adam Kirrander, and Russell S. Minns. Phys. Rev. Lett. 120, 183003 (2018). DOI: 10.1103/PhysRevLett.120.183003. Open access: arXiV 1805.02170