A novel method to determine collisional energy transfer efficiency by Fourier transform ion cyclotron resonance mass spectrometry

Heeren, R. M. A. and Vékey, Károly (1998) A novel method to determine collisional energy transfer efficiency by Fourier transform ion cyclotron resonance mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY, 12 (17). pp. 1175-1181. ISSN 0951-4198

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Abstract

novel method is presented here to determine accurately the conversion efficiency in low energy collision processes. Using blackbody infrared radiation, the initial thermal energy of a selected molecular ion is both well defined and well known. Collisional activation is subsequently used to probe the additional energy needed to reach a particular final internal energy distribution, characterized by a given fragmentation rate (e,g, 50 % of the molecular ion being decomposed). The method is discussed for collision induced dissociation under multiple collision conditions using resonant excitation in a Fourier transform ion cyclotron resonance ion trap. By variation of the thermal energy content the collisional energy necessary to obtain 50% fragmentation rate is also changed. Knowing this change, the collisional to internal energy transfer can accurately be determined. In the case of Leucine-Enkephaline using Ar collision gas it was shown that 4.4% of the laboratory frame collision energy is converted into internal energy in the resonant excitation collision cascade, In individual collisions 9.6% of the centre of mass collision energy is converted into internal energy. Note, that this value is accurately determined as an average for collisions in the 4-6 eV centre of mass collision energy range, but is approximately the same in the 0-4 eV range as well.

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