| Description |
Guided ion beam tandem mass spectrometry is used to probe the kinetic energy dependence of both Cu2+(H2O)n, where n = 5 - 10, and CuOH+(H2O)n, where n = 0 - 4 colliding with Xe. The resulting cross sections are analyzed using statistical models to yield 0 K bond dissociation energies (BDEs). The primary dissociation pathway for Cu2+(H2O)n consists of water loss followed by the sequential loss of additional waters at higher energies until n = 7, at which point charge separation to form CuOH+(H2O)m + H+(H2O)n-m-2 is energetically favored. The primary dissociation pathway for CuOH+(H2O)n is also water loss and is followed by the sequential loss of additional waters at higher energies until n = 1 at which point OH loss become competitive. The BDEs for loss of water and OH from CuOH+(H2O) are combined in a thermodynamic cycle with literature values to derive BDEs for the loss of OH from CuOH+(H2O)n, where n = 0, 2 - 4. Infrared multiple photon dissociation (IRPD) spectroscopy is performed on CuOH+(H2O)n, where n = 2 - 9. These spectra are characterized through comparison to theoretical spectra of low energy isomers. It is found that CuOH+(H2O)n prefers a 4-coordinate inner shell, although contributions from 5-coordinate geometries cannot be ruled out in most cases and are clearly present for n = 7. This preference is found in the Cu2+(H2O)n system as well and differs from the Cu+(H2O)n system, which prefers a 2-coordinate inner shell. Electronic structure calculations are further employed to yield BDEs which agree reasonably well with experimental values. A method for modeling kinetic energy release distributions (KERD) on a guided ion beam tandem mass spectrometer is proposed. This method achieves reasonable agreement with dissociations occurring over loose transition states when reactants have little energy in excess of the dissociation threshold. Current limitations and future possibilities of this method are discussed in detail. |
