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Photolysis TOF System For Kinetic Studies Delivered To Leeds University

Photo of kinetic studies system

Kore delivered this instrument in March 2004, following placement of an order by the Department of Chemistry at Leeds University in October 2003. The system has a time-of-flight mass spectrometer system (TOF-MS) that will perform time- resolved kinetic studies of gas phase reactions on the millisecond timescale. Professor Mike Pilling and Dr. Mark Blitz contacted Kore to discuss their experiment, and out of the discussions came a design that we are all now excited to see turn into a completed instrument.

The system is based on a quartz reaction cell within a bench-mounted, high pumping capacity vacuum system, through which a carrier gas flows at ~1 mbar pressure. The carrier gas also contains other key components. A 10Hz photolysis laser is guided into this reaction cell to create radicals R° from a precursor. Following this photolysis step, the radicals react with a further component X, which is also mixed at low concentration with the He or Ar.

System schematic

The RX component and carrier effuse from a small orifice (~1mm diameter) in the reaction cell. Components in the emerging plume are then ionised with a vacuum ultraviolet (VUV) laser pulse, creating RX+ ions that can be pulsed with a Kore TOF source and then measured by the TOF mass spectrometer. The counting system is analogue, owing to the expected data rate, and the results are recorded on a fast digital oscilloscope.

By varying the delay time between the first laser pulse to create radicals and the second laser pulse to create RX ions, the kinetics of the R°+X=RX reaction can be investigated. The time constants for the reactions of interest range between 0.1 microseconds and 1000 microseconds (1 millisecond).

For an example of the work that is being done with this apparatus, please click here


Last updated: 22 March 2006 21:20

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