Research Papers in Physics and Astronomy


Date of this Version



Published in Journal of The American Society for Mass Spectrometry 23 (2012), pp. 834-841; doi: 10.1007/s13361-0120346-6


Copyright © 2012 American Society for Mass Spectrometry. Published by Springer. Used by permission.


We report on the fragmentation of ionized pyridine (C5H5N) molecules by focused 50 fs, 800 nm laser pulses. Such ionization produces several metastable ionic states that fragment within the field-free drift region of a reflectron- type time of flight mass spectrometer, with one particular metastable dissociation being the leading fragmentation process. Because the time of flight is no longer dependent in a simple way on the mass of the ion, the metastable decay is manifested as an unfocused peak on the mass spectrum that appears at a time of flight not corresponding to an integer mass. A previously-developed method is used to identify the precursor and final masses of these ions. The metastable process that creates the most prevalent peak is shown to be C5H5N+ → C4H4+ + HCN. Simulations confirm this result and place restrictions on the processes for several other observed metastable reactions.

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