Velocitas VMI system
Unique solutions for your research
- Full systems or component combinations
- Fully customisable
- Modular design
- Retrofit capabilities
- User friendly
- Full system upgrades
Velocity Map Imaging (VMI) is a powerful experimental technique used in laser physics and physical chemistry research to investigate gas phase ionisation, fragmentation dynamics, photoelectron spectroscopy and much more. VMI provides details on velocity, angular distribution and mass of charged particles, offering more complete information than many standard ion imaging and spectrometry techniques.
With rapid advances in charged particle detection and laser technology in recent years, velocity map imaging is becoming an even more popular technique in research laboratories worldwide. To support this developing market, we have collaborated with internationally renowned physical chemists and laser physicists to develop a range of VMI instrumentation and accessories to provide advanced VMI capabilities in various research laboratories.
We recognise the need for custom solutions to fit individual experimental needs, so the Velocitas VMI Spectrometer has a unique modular design with customisable components. The bespoke system can be offered as a complete spectrometer solution, while individual components are designed to be compatible with standard laboratory installations. This provides the possibility of retrofitting into existing experimental setups and the potential for full system upgrades.
Velocitas VMI spectrometer
Part 1: VMI ion optics
We have a choice of ion optics for a range of experimental needs, including high resolution imaging, high energy photoelectron imaging or VMI with dc slicing. The ion optics have configurable options including different mounting possibilities, optional flight length and mu-metal shielding for optimal operation. Velocitas VMI ion optics have dual polarity, giving you the choice to image positive ions or electrons and negative ions, all with the flick of a switch.
Part 2: Vacuum imaging detector
Our Vacuum Imaging Detector typically consists of open-faced MCPs and phosphor screen in vacuum, with external camera and image processing software. The detector can be configured for your specific application, with a choice of active area size, MCP gain, choice of phosphor, as well as additional TOF and MCP gating options.
Part 3: Camera and Image32 software
Our selection of high resolution cameras come with Photek’s established Image32 image processing and data acquisition software for a complete detection solution to your vacuum imaging experiment.
Part 4: Vacuum chambers and pumps
The system typically incorporates more than one differentially pumped vacuum chamber (source chamber and interaction chamber). The vacuum chamber(s) design can be tailored for your specific applications, including the option of laser access from more than one direction and extra ports for vacuum accessories, all neatly contained in a single frame.
Part 5: Pulsed valve
To efficiently and reliably deliver your target gas from the source chamber to the interaction chamber, we offer a choice of pulsed valves, with configurable options depending on your specifications including target density, molecular beam temperature and repetition rate.
Associated electronics and components
To complete the system, we include all required electronics: high voltage, ultra-stable, reverse polarity power supply units for the ion optics; power supply unit with tracking for the detector; MCP gating module; controllers for the pulsed valve and vacuum system; signal delay generator to co-ordinate timing between your laser system, the pulsed gas, detector gating and imaging camera; computer with Photek’s established Image32 image processing software.
Velocitas VMI applications
The Velocitas VMI Spectrometer is used in Velocity Map Imaging experiments with laser pulse durations from nanoseconds to attoseconds and photon wavelengths from IR to XUV and X-ray. Capturing 3D information on kinetic energy, angular distribution, and signal intensity, the spectrometer can be used as a diagnostic tool in femtosecond and attosecond laser characterization, or in fundamental investigations of electron processes, stereochemistry, and photodissociation dynamics.
Specific examples of Velocitas VMI applications are:
Photoelectron spectroscopy provides fundamental information on electronic structure in atoms and small molecules, playing an integral part in investigations into electron dynamics and coherent control.
Attosecond laser characterisation
By observing the intensity and angular distribution of photoelectron interference patterns from XUV-IR photoionisation, the relative phase is known and the electric field of attosecond pulses can be reconstructed.
Imaging the 3D velocity distribution of state-selected reaction products helps build a picture of molecular stereodynamics and how it affects chemical reactions and energy transfer processes.
Fundamental dynamical processes can be characterised by recording photoelectron and/or photoion kinetic energy distributions for different delays in pump-probe spectroscopy experiments. VMI is an increasingly popular technique in a wide range of research laboratories. We aim to understand your specific application to be able to offer a bespoke spectrometer design to fit your individual needs.
Velocitas VMI research and collaborations
We have a long history of collaboration with world-class research institutions and ultrafast laser laboratories, leading to the development of the Velocitas VMI range of instrumentation. In the design and testing of the Velocitas VMI PRIME and DOUBLE PRIME ion optics, we worked with
- Prof Marc Vrakking, MBI Berlin
- Prof Mike Ashfold, University of Bristol
- Sandia National Laboratories, Prof. David Chandler, Chemical Dynamics
- Weizmann Institute of Science, Israel The Attosecond Science Group
- University College London, UK
- Durham University, UK
- Politecnico di Milano, Italy
- University of Pennsylvania, USA
- University of Nottingham, UK
- Université Bordeaux, France
- Herriot Watt University, UK
- University of Leeds, UK
- … plus many more.