PimMS: Pixel Imaging Mass Spectrometry

Mass spectrometry is a powerful analytical technique widely used to identify unknown compounds and to elucidate the structure of molecules. The PImMS (Pixel Imaging Mass Spectrometry) project is developing a fast imaging sensor for use in a next-generation time-of-flight mass spectrometer (TOF-MS) with unique imaging capabilities. Recent progress in semiconductor technologies presents the opportunity to produce a novel detector that will allow us to marry the ion-imaging technique with mass spectrometry. For each mass, the new instrument will image with high precision the complete velocity or spatial distribution of the ions at their point of formation. This will take mass spectrometry from its current role as a one-dimensional ‘weighing’ technique into a multi-dimensional world, in which spatial, velocity, and even coincidence information is provided as a function of mass. The novel pixel detector used in the instrument will be based on the deep submicron CMOS process INMAPS, originally developed by STFC-RAL for use at the International Linear Collider.

Potential applications are wide-ranging. In spatial mapping mode key applications will be in ‘single shot’ molecular imaging of surfaces, and in high-throughput sampling; the extra spatial dimension will allow conventional mass spectra of large numbers of samples to be acquired in parallel, potentially enabling faster and more efficient use of mass spectrometry. In velocity mapping mode the technique will find important applications in molecular fragmentation studies, providing important structural information in addition to the fragment masses which could be important in understanding complex organic molecules.

PimMS collaboration : Oxford Physics and Chemistry; RAL

PImMS Sharepoint Server

PImMS1 sensor: 72x72 pixels, 70x70 um², four time stamps per pixel, time resolution 50 ns over 200 usec experimental period

PImMS camera: USB readout, 500 frames (experiments) per sec for PImMS1 sensor

June 2011: Five 405 nm laser shots recorded by PImMS1

August 2011: First velocity mapping images on the 193 nm fragmentation of N,N-dimethylformamide (DMF). DMF is a prototype molecule for studying peptide bond cleavage.

Proof of concept experiments are described in this 2008 paper.

Recent conference presentations and papers:

• Proceedings of WIT2010 workshop (Berkeley, February 2010)
• Presentation at VERTEX2011 workshop (Rust, Austria, June 2011)

Link to Oxford Fast Imaging Seminars: July 2010 , September 2010 and May 2011.

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Updated 21 September 2011by Andrei Nomerotski

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