Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (07): 1574-1578.doi: 10.3866/PKU.WHXB20110633


Application and Improvement in the Ion Velocity Imaging of Threshold Photoelectron-Photoion Coincidence Measurements

ZHEN Cheng, TANG Xiao-Feng, ZHOU Xiao-Guo, LIU Shi-Lin   

  1. Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2011-03-30 Revised:2011-04-18 Published:2011-06-28
  • Contact: ZHOU Xiao-Guo
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (10979042, 21073173) and National Key Basic Research Program of China (973) (2007CB815204).


A series of electrodes were used to form a new accelerated electric field for ion focusing optics of a threshold photoelectron-photoion coincidence (TPEPICO) mass spectrometer. Ion groups with higher kinetic energy gradually expanded along the direction of flight while they were restricted along the direction perpendicular to the flight tube. Consequently, contractible velocity imaging was achieved on the surface of the detector for all the ions where a magnification factor (N) of less than 1 was obtained for the images. Therefore, good kinetic energy resolution and mass resolving power were obtained simultaneously. Using this novel focusing lens the dissociation of vibrational state-selected O2 ions in the B2Σg- state was reinvestigated and three-dimentional time-sliced velocity images of the O fragment were recorded. By comparing the kinetic energy released distributions of the O that dissociated from the two dissociation channels, satisfied velocity imaging was obtained for the ions with a wide kinetic energy range.

Key words: Ion velocity imaging, Threshold photoelectron-photoion coincidence, Time-of-flight mass spectrometer, Dissociation dynamics


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