Structures of Gaseous Ions by Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy PDF Download

Author: Khadjch Rajabi
Publisher:
ISBN:
Category : Infrared spectroscopy
Languages : en
Pages : 0

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Author: Khadjch Rajabi
Publisher:
ISBN:
Category :
Languages : en
Pages : 560

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Author: Richard Alexander Marta
Publisher:
ISBN:
Category :
Languages : en
Pages : 290

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Book Description
Mass-selected infrared multiple photon spectroscopy (IRMPD), Fourier transform ion cyclotron resonance (FT-ICR) kinetic experiments, RRKM and electronic structure calculations have been performed in order to propose a complex mechanism involving the formation of the proton-bound dimer of water (H5O2) from 1,1,3,3-tetrafluorodimethyl ether. It has been found that the reaction is facilitated by a series of sequential exothermic bimolecular ion-molecule reactions. Evidence for the dominant mechanistic pathway involving the reaction of CF2H-O=CHF2, an ion of m/z 99, with water is presented. The primary channel occurs via nucleophilic attack of water on the ion of m/z 99 (CF2H-O=CHF), to lose formyl fluoride and yield protonated difluoromethanol (m/z 69). Association of a second water molecule with protonated difluoromethanol generates a reactive intermediate which decomposes via a 1,4-elimination to release hydrogen fluoride and yield the proton-bound dimer of water and formyl fluoride (m/z 67). The 1,4-elimination of hydrogen fluoride is found to be strongly supported by the results of both RRKM theory and electronic structure calculations. Lastly, the elimination of formyl fluoride occurs by the association of a third water molecule to produce H5O2 (m/z 37). The most probable isomeric forms of the ions with m/z 99 and 69 were found using IRMPD spectroscopy and electronic structure theory calculations. Thermochemical information for reactant, transition and product species was obtained using MP2/aug-cc-pVQZ//MP2(full)/6-31G(d) level of theory.

Author: Dilrukshi Manjalika Patuwathavithana Peiris
Publisher:
ISBN:
Category : Fourier transformations
Languages : en
Pages : 316

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Author: Clifford H. Watson
Publisher:
ISBN:
Category :
Languages : en
Pages : 27

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Ions trapped in a Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer exhibited enhanced Infrared Multiple Photon Dissociation (IRMPD) when irradiated sequentially by two carbon dioxide lasers using a novel IRMPD probe/pump photodissociation scheme. A low power pulsed (probe) laser tuned to a resonant infrared absorption band promoted trapped ions to vibrationally excited states, but had insufficient energy to cause photodissociation. Subsequent irradiation of the excited ions with a fixed-frequency, nonresonant, continuous wave (pump) laser induced photofragmentation. Photodissociation spectra were obtained by varying the wavelength of the probe laser. A novel White-type cell which dramatically enhances the effect of the probe laser has been designed and constructed for use with these experiments. Infrared multiple photo dissociation, Infrared spectra of ions, Fourier transform ion cyclotron resonance mass spectrometry, Lasers, Ions, Kinetics, Gas analysis, Collisions, Molecular structure, Energy levels, Probes. (jg).

Author: Anouk M. Rijs
Publisher: Springer
ISBN: 3319192043
Category : Science
Languages : en
Pages : 409

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The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.

Author: Jonathan K. Martens
Publisher:
ISBN:
Category :
Languages : en
Pages : 277

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The structures of gaseous sodiated poly(alanines), Ala8-12 Na+, were studied using infrared multiple photon dissociation (IRMPD) spectroscopy complimentarily to molecular dynamics and quantum chemical methods.

Author: Ryan Patrick Dain
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 76

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A combination of theoretical chemistry and "action" spectroscopy has become the most used tool for the exploration of gas-phase molecular ions. In this study, density functional theory (DFT) calculations were used to test the validity of conclusions drawn from the results of a matrix-isolation infrared (MI-IR) experiment and develop a modeling method that could be used for metal-coordinating chlorate ion pairs. That modeling method was then used in comparison with experimental infrared multiple photon dissociation (IRMPD) spectroscopy to determine the structures of metal-chlorate anions. In addition to structural information, the effect of the modeling method on spectral correlation was also investigated.

Author: Kenneth W. Busch
Publisher: Elsevier
ISBN: 0080469280
Category : Science
Languages : en
Pages : 721

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Chiral Analysis covers an important area of analytical chemistry of relevance to a wide variety of scientific professionals. The target audience is scientific professionals with an undergraduate background in chemistry or a related discipline, specifically organic chemists, researchers in drug discovery, pharmaceutical researchers involved with process analysis or combinatorial libraries, and graduate students in chemistry. Chapters have been written with the nonspecialist in mind so as to be self-contained. * Broad coverage - spectroscopic and separation methods covered in a single volume * Up-to-date and detailed review of the various techniques available and/or under development in this field * Contributions from leading experts in the field

Author: Sabrina M. Martens
Publisher:
ISBN:
Category :
Languages : en
Pages : 109

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Infrared multiple photon dissociation (IRMPD) spectroscopy has been coupled with electronic structure calculations in order to elucidate the structures of several small biological molecules including: uracil, 5-fluorouracil, 5-fluorocytosine, ferulic acid, and a number of their related analogs. IRMPD is a powerful technique, that when combined with electronic structure calculations can provide convincing evidence for the structural characterization of ions in the gas phase. Isomers of uracil and 5-fluorouracil (5-FU) have been characterized by calculations performed at the MP2(full)/aug-cc-pVTZ level of theory; however, infrared multiple photon dissociation spectroscopy experiments proved to be unsuccessful for these species. Geometry optimization and frequency calculations have isolated the dominant isomer(s) for neutral and deprotonated uracil and 5-fluorouracil, along with several cluster interactions involving water, methanol, ammonia, and methylamine. For both uracil and 5-FU, a single relevant neutral isomer was determined, with each isomer existing in the diketo, as opposed to the enol form. Following the deprotonation of this neutral isomer, both uracil and 5-FU were permitted to form anionic cluster ions with water, methanol, ammonia, or methylamine, and based on the relative Gibbs free energies (298 K) of the calculated isomers, relevant cluster interactions were determined. For each cluster, several sites of intramolecular interaction were found to exist; however, interaction at the site of deprotonation was the most favourable in every instance. Ionic hydrogen bond interactions have been found in several clusters formed by 5-fluorocytosine (5-FC).