Direct dynamics simulations of collision- and surface-induced dissociation of n-protonated glycine. Shattering fragmentation

Samy O. Meroueh, Yanfei Wang, William L. Hase

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95 Scopus citations


Direct dynamics classical trajectory simulations are used to study energy transfer and unimolecular dissociation in collisions of N-protonated glycine, (gly-H)+, with an argon atom and a hydrogenated diamond {111} surface. The (gly-H)+ potential is represented by the AM1 semiempirical electronic structure theory and analytic potentials developed previously are used for the diamond surface and the (gly-H)+/Ar and (gly-H)+/ diamond intermolecular potentials. The AM1 potential for (gly-H)+ gives the same collisional energy transfer distributions as does the AMBER empirical force field. For (gly-H)+ + diamond {111} at a collision energy and angle of 70 eV and 45°, the average percent energy transfer to (gly-H)+ vibration/rotation, to the surface, and to final ion translation are 12, 38, and 50, respectively. A distribution of (gly-H)+ dissociation products are observed in these collisions, with ∼55% of the dissociations occurring while (gly-H)+ collides with the surface, i.e., shattering fragmentation. Shattering is initiated when the orientation of (gly-H)+ and the "hardness" of the collision "drives" a H-atom from CH2 to the carbonyl carbon or a H-atom from NH3 to the carbonyl oxygen or ejects a H2 molecule from NH3. Shattering is not important in (gly-H)+ collisions with Ar at 13 eV and an impact parameter of zero, but as found for the surface collisions, the Ar collision may "force" H-atom transfer. The simulations suggest that nonstatistical fragmentation dynamics may be important in the collisional dissociation of protonated amino acids and peptides. The collision may directly "drive" the ion to a fragmentation transition state structure.

Original languageEnglish (US)
Pages (from-to)9983-9992
Number of pages10
JournalJournal of Physical Chemistry A
Issue number42
StatePublished - Oct 24 2002
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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