Gas-phase studies of metal ions and metal-containing complex ions by Fourier transform ion cyclotron resonance mass spectrometry.

摘要

Fourier transform ion cyclotron resonance mass spectrometry (FTICR/MS) has been employed as a method of analysis to study gaseous metal and metal-containing complex ion chemistry. Certain advantages of FTICR/MS, such as high mass resolving power and extended ion trapping times, are discussed and utilized to investigate these chemical moieties.;The simplest of the chemical species, the elements, have been studied by directly coupling a radio frequency (rf) glow discharge (GD) ionization source to an FTICR/MS. By use of rfGD-FTICR/MS, elemental analysis of nonconducting as well as conducting materials has been shown, in contrast to the dcGD-FTICR/MS method which is only applicable to conducting samples. The high mass resolution capability of FTICR/MS is an attractive advantage for elemental analysis since many isobaric interferences common to elemental analysis can be distinguished. A glass standard, SRM 1412, has been analyzed by rfGD-FTICR/MS and is the first example to date of the ability of this technique to examine nonconducting materials. Metal ions produced from rfGD ionization have been identified and are representative of the metal oxides contained within the glass matrix. Additionally, ultrahigh mass resolving powers (>200,000 full width at half maximum) have been reported, indicating rfGD-FTICR/MS can be a powerful tool in elemental analysis.;Further FTICR/MS investigation into the area of gaseous metal ion chemistry has been accomplished by studying the structure and reactivity of partially solvated ruthenium complex ions. A number of unimolecular dissociation reactions, where loss of solvent molecule from the complex ion is the reaction mechanism, have been kinetically characterized by monitoring the dissociation of these species as a function of ion trapping time. Dissociation energetics have also been obtained by analyzing the kinetics of these desolvation processes over a range of temperatures. The zero-pressure activation energies calculated from Arrhenius-type analysis have been shown to deviate significantly from those energy values obtained by truncated Boltzmann computations and master equation modeling. Semiempirical and ab initio theoretical methods have been employed for geometry optimizations and vibrational property calculations. The results of these calculations have been compared and the applicability to the truncated Boltzmann approach and master equation modeling has been discussed.