Determination of bond dissociation energies using mass spectrometry

Abstract

ABSTRACT:Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/ MS) offers the opportunity for gas phase cluster formation reactions at very low pressures and at temperatures that are different from room temperature. Reactions take place with single positive-charge metal ions that are normally ϩ2, ϩ3, ϩ4, etc., charged in solution. The ions formed are detected by measuring the current induced by their cyclotron rotation, but they cannot be physically separated and collected. Collisioninduced dissociation (CID) is widely used for ion-structure determination via the fragmentation of the excited ions. CID study aims to determine the relationship between the V pp [peak-to-peak voltage of the radiofrequency (rf) pulse] and the massto-charge (m/z) ratio, which will be used for the calculation of the center-of-mass translational kinetic energy (Ek cm ) of the excited ion under investigation. CID studies are restricted to stable ions with relatively high abundance. Nevertheless, with the evolution of computational chemistry, such problems can be overcome whereby CID calculations will be used to provide the substantial parameters for computer software, such as the Gaussian 03 program, for the structure determination of the less stable Ni x S y Ϫ anions. The latter constitutes the core for our current research.