| Summary: | The determination of binding energy is a very important piece of information that an experiment can provide. We have devised a new experimental procedure to measure binding energies for unimolecular (metastable) decay of multiply charged metal ligand cluster ions in gas phase.
The new technique consists in preparing clusters by supersonic expansion, and in generating metal ligand clusters by pick up technique. A high resolution double focusing mass spectrometer having reversed sector geometry is used to obtain mass analysed ion kinetic energy spectra. The evaporative ensemble statistical model by C. E. Klots is used to analyse the kinetic energy releases and to obtain the corresponding binding energies. Our new experimental method has been applied to measure the binding energy for the loss of one neutral molecule in a unimolecular (metastable) dissociation in H+(H2O)n , *H +(NH3)n and H+(CH 3OH)n for n ≤ 30. The main results were:
(i) for n > 6 each fragmentation corresponds to breaking one hydrogen bond
(ii) no magic numbers were observed.
This experimental procedure was used to measure the binding energy for theloss of one neutral molecule in the unimolecular (metastable) decay of [M(L)n2+ for n ≤ 20, where M = Mg, Ca, Sr and L = H2O, NH 3, CH 3 OH.
This investigation determined that:
(i) the coordination number is six for all the metal solvent cluster ions, except for [Mg(NH3 n]2+ having coordination number equal to four;
(ii) the double charge affects the binding interactions on the solvation shells up to n = 20 with the exception of [Sr(H2O)n]2+, for which n = 14;
(iii) binding energies correspond to breaking one hydrogen bond;
(iv) no magic numbers were detected.
* Printed version:”H+(H2O)n, H+(H2O)n,and H+(CH3OH)n for n ≤ 30.”
correct version ”H+(H2O)n, H+(NH3)n,and H+(CH3OH)n for n ≤ 30.”
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