Significant technical advances have been made in the application of the triple-quadrupole double-octopole mass spectrometer for absolute total state-selected cross section measurements of ion-molecule reactions involving O+(4S degree(s), 2D degree(s), 2P degree(s)). By controlling the collision energies for dissociative charge transfer collisions of He+ (Ne+, Ar+) plus O2 in a radio frequency (rf) octopole ion guide gas cell, and by applying appropriate effective ion trapping potentials to the rf octopole ion guide, we have demonstrated that state-selected O+(4S degree(s)), O+(2D degree(s)), and O+(2P degree(s)) reactant ion beams with high purities and usable intensities can be prepared for scattering experiments.
Absolute total cross sections for the formation of C/sup +/ , O/sup +/ , and ArC/sup +/ in the collisions of Ar/sup +/ (/sup 2/ P/sub 3/2,1/2/ )+CO have been measured over the center-of-mass collision energy (E/sub c.m./ ) range of approx.4--123 eV. The observed appearance energies for C/sup +/ and O/sup +/ are in agreement with the thermochemical thresholds for the C/sup +/ (/sup 2/ P)+O(/sup 3/ P) and O/sup +/ (/sup 4/ S/sup 0/ )+C(/sup 3/ P) product channels, respectively. The cross sections for C/sup +/ are significant compared to those for CO/sup +/ . At E/sub c.m./ = 12.9 eV, the analysis of the kinetic energy distributions of C/sup +/ and CO/sup +/ supports the conclusions that many excited vibronic states of CO/sup +/ are populated and that the C/sup +/ ions are formed by predissociation of electronic excited CO/sup +/ .
Ionization efficiency (lE) data for the M+, MCp+, and MCp2+ ions of ferrocene (FeCp2), nickelocene (NiCp2), and ruthenocene (RuCp2) are interpreted by a deconvolution–convolution technique to yield ionic bond dissociation energies in the 6–7 eV range for D(CpM+–Cp) and in the 4–5 eV range for D(M+–Cp). Additional direct experimental evidence in support of these values was obtained from lE data for appropriate metastable ion transitions.Probable errors in the interpretation of lE data for other molecular systems are discussed with reference to the approach for metallocenes presented here.
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA photoelectron-photoion coincidence study of iron pentacarbonylK. Norwood, A. Ali, G. D. Flesch, and C. Y. NgCite this: J. Am. Chem. Soc. 1990, 112, 21, 7502–7508Publication Date (Print):October 1, 1990Publication History Published online1 May 2002Published inissue 1 October 1990https://pubs.acs.org/doi/10.1021/ja00177a008https://doi.org/10.1021/ja00177a008research-articleACS PublicationsRequest reuse permissionsArticle Views202Altmetric-Citations68LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
We present a differential retarding potential (DRP) method for improving the kinetic energy resolution of a reactant ion beam for scattering experiments. This method allows ion-molecule reaction absolute total cross-section measurements to be performed down to thermal energies using the simple electrostatic aperture ion lenses of a tandem quadrupole mass spectrometric ion-molecule reaction apparatus, even though the reactant ions are formed originally with a broad kinetic energy distribution. To illustrate the principle of the DRP method, examples are given for its application to reactant ion beams prepared in an electron impact ion source and in an ion-molecule reaction ion source.
Absolute total cross sections for H2O+ and OH+ formed by the O+(4So)+H2O reaction have been measured in the center-of-mass collision energy (Ec.m.) range of ≊0.1–60 eV. The cross sections for H2O+ are greater than those reported previously. The structure observed in the cross section curve for OH+ suggests that the OH++OH channel is produced at Ec.m.≊0.1–5.0 eV via a long-lived complex mechanism, while the OH++O+H channel is formed at Ec.m.≊5–60 eV by a short range charge transfer-predissociation pathway.
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