Update Jan 2020: collected results are now online at ePSdata, which supersedes the previous OSF pages. This now includes DOIs for each dataset from Zenodo, and post-processing with the new python version of ePSproc.
An OSF project, collecting photoionization calculations (ePolyScat), and notes, is now available. This will be an ongoing resource for researchers in photoelectron spectroscopy, interferometry and related areas, and is part of our Open Science initiative.
Our Direct Ion Detection Technology Project is wrapping up in its current form, with a plan to reemerge – bigger and better – next year. See this PDF for a summary of the project to date, and plans for future work. Further details can also be found on the project webpages.
Our work in JCP has the (dubious?) honour of being selected as their Christmas card.
For more details of the work, see the press release (April 2017) and the original article (Feb 2017).
Example of new detector mounting in our VIRP chamber, as part of our work testing ion detection technologies. The image shows a Mega-Spiraltron detector for high-pressure (up to 10^-3 mbar) charged particle detection.
Here’s some images of the VIRP chamber in a pumping configuration, with turbo pump and gauges ready to go.
UPDATE: Dec. 2017
The figure above has made it as the JCP Christmas card!
The full JCP special issue on Velocity Map Imaging Techniques is also now officially ready, see this page, or this PDF, for all the details.
UPDATE: 4th April 2017
The article is now published in the Journal of Chemical Physics, with an accompanying press release, The Inner Lives of Molecules, from AIP.
The full dataset and analysis scripts are now also available via OSF, DOI: 10.17605/OSF.IO/RRFK3.
Feb. 2017 – new article on the arXiv:
The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged particle imaging measurements, in which the particle time-of-flight is recorded along with (x,y) position. Coupling the PImMS camera to an ultrafast pump-probe velocity-map imaging spectroscopy apparatus therefore provides a route to time-resolved multi-mass ion imaging, with both high count rates and large dynamic range, thus allowing for rapid measurements of complex photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet wavelengths for the probe pulse allows for an enhanced observation window for the study of excited state molecular dynamics in small polyatomic molecules having relatively high ionization potentials. Herein, preliminary time-resolved multi-mass imaging results from C2F3I photolysis are presented. The experiments utilized femtosecond UV and VUV (160.8~nm and 267~nm) pump and probe laser pulses in order to demonstrate and explore this new time-resolved experimental ion imaging configuration. The data indicates the depth and power of this measurement modality, with a range of photofragments readily observed, and many indications of complex underlying wavepacket dynamics on the excited state(s) prepared.
Now published in JCP:
The Journal of Chemical Physics 147, 013911 (2017);
DOI: http://dx.doi.org/10.1063/1.4978923
Also on Authorea, DOI: 10.22541/au.149030711.19068540
A couple more from the Lytro lightfield camera… mouse around to move the images and change focus.
A little more progress for our Direct Ion Detection project: the images above and below show some developments of our VIRP chamber (for rapid vacuum instrument prototyping), showing v2.0 of the charged particle spectrometer stack (following a rebuild) with some of the in vacuo wiring attached. Time-lapse build footage to follow! This configuration will allow us to perform experiments with direct ion detection, and optimise the methodologies and technologies.
Update: time-lapse build footage is now online.
For further background details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).
Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)
The Lytro digital camera introduces a Shack-Hartmann configuration into a digital SLR camera. Why? For “lightfield” (wavefront) imaging, allowing for depth information in the captured data. While this kind of thing has long been used for scientific instruments, in particular for laser beam measurements, the Lytro camera brings this capability (and the not insignificant post-processing know-how and hardware required) to photography in the visible. For rather more detailed information, check out the PhD thesis of Ren Ng, the founder of Lytro.
Here’s a demo image of our VIRP chamber, note that mousing around the image and clicking allows one to change the focus of the image, and the imaging plane. Mouse wheel to zoom. It’s going to be an excellent tool for scientific imaging!
* Banner image from Lytro.com.
Some progress for our Direct Ion Detection project: the image above shows the beginnings of a test set-up based around a Hamamatsu MPPC chip, which will be coupled to a scintillator coating to form a complete “direct” ion detection system. This will then be combined with our VIRP chamber (for rapid vacuum instrument prototyping), allowing us to perform experiments with direct ion detection, and optimise the methodologies and technologies. This is a more refined version of the crude test set-up from a couple of weeks ago!
For further backgournd details, see:
A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter
Edward S. Wilman, Sara H. Gardiner, Andrei Nomerotski, Renato Turchetta, Mark Brouard and Claire Vallance
Rev. Sci. Instrum. 83, 013304 (2012).
Improved direct detection of low-energy ions using a multipixel photon counter coupled with a novel scintillator
Winter, King, Brouard & Vallance
International Journal of Mass Spectrometry, 397–398, 27–31 (2016)