Observation and Identification of Metastable Excited States in Ultrafast Laser-Ionized Pyridine

Authors

David B. Foote, University of Nebraska-Lincoln
Timothy D. Scarborough, University of Nebraska-LincolnFollow
Cornelis J. Uiterwaal, University of Nebraska - LincolnFollow

Date of this Version

2012

Citation

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

Comments

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

Abstract

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.

Includes supplementary materials.