Table of Contents
ISRN Physical Chemistry
Volume 2012, Article ID 959074, 9 pages
Research Article

Design of Velocity Map Imaging Spectrometer Equipped with a Mass Gate Discriminating Particular Photofragments

1Department of Photo-molecular Science, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
2Department of Structural Molecular Science, Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan

Received 29 January 2012; Accepted 15 March 2012

Academic Editors: C. L. Huang, H. Ihee, H. Saint-Martin, D. Strout, L. Vattuone, and S. Yang

Copyright © 2012 Koichiro Mitsuke et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A photoionization spectrometer for velocity map imaging has been developed for measuring the scattering distribution of fragment ions from polyatomic molecules. The spectrometer contains a mass gate and an ion reflector which are able to discriminate ions with a particular mass-to-charge ratio m/z. The basic functions and feasibility of these devices were tested experimentally and theoretically. First, the photoions from Kr and C60 were extracted into a time-of-flight (TOF) mass spectrometer by a transient or continuous electrostatic field. When the pulse application on the mass gate was tuned to the arrival timing of ions with a specific m/z, the peak of the selected ions alone was present on a TOF spectrum. Second, compatibility between velocity map imaging and ion discrimination was investigated by the computer simulations of the ion trajectories of photofragments from C60. A pulsed voltage was applied to the mass gate synchronously with the arrival timing of C58+ ions. The initial three-dimensional velocity distribution of C58+ was projected onto the image plane with an energy resolution better than 10 meV. The C58+ image was free from the contamination of other ions such as C60+ and C56+.