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You searched for subject:(Protonated complexes). Showing records 1 – 2 of 2 total matches.

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The Ohio State University

1. Dzugan, Laura C. Theoretical Treatments of the Effects of Low Frequency Vibrations on OH Stretches in Molecules and Ion-Water Complexes that Undergo Large Amplitude Motions.

Degree: PhD, Chemistry, 2017, The Ohio State University

A vibrational spectrum of a molecule provides the frequencies and intensities associated with the vibrational motions in the molecule. As it is not always easy to assign specific vibrational motions to the peaks in measured spectra, theoretical calculations are used to assist in identifying the motions responsible for the observed transitions. The harmonic oscillator approximation is often used when calculating the frequencies and intensities for the vibrations in a molecule. However, anharmonicities can arise from strong couplings between vibrations. As such, adjustments to the calculations are needed to accurately evaluate the vibrational energy levels. This thesis uses several strategies to address the anharmonic effects in vibrational spectra, specifically those involving couplings between low frequency motions and high frequency OH or CH stretches.In the vibrational spectra of M2+ OH-(H2 O)n=4-6 (M = Mg, Ca) and the protonated water trimer and tetramer (H+(H2O)n=3,4), there are two types of bands in the OH stretch region; narrow peaks due to isolated OH stretches and a broadened feature that is attributed to OH stretches involved in H-bonding. The effects of low frequency motions on the H-bonded OH stretches were analyzed through calculations based on an adiabatic separation of the inter- and intramolecular vibrations. For these calculations, displacement geometries were sampled from the equilibrium structure based on the harmonic ground state probability amplitude using Monte Carlo sampling. Then only the frequencies and intensities for the OH stretches and HOH bends were calculated by constraining the remaining internal coordinates at their displaced geometries. As the calculated spectra had generally good agreement with the measured spectra, it was concluded that the H-bonded OH stretch frequencies were very sensitive to the placement of the water monomers within the molecule. However, the studies on the protonated water clusters proved to be more of a challenge due to other anharmonicities that this adiabatic approach did not take into account.To improve the analysis on the protonated water trimer and tetramer, the frequencies and intensities of the vibrations were calculated using second-order perturbation theory where the normal modes were defined as displacements of internal coordinates. From these calculations, the combination bands and overtones in the spectra were assigned and the effects of near degeneracies between vibrational states were analyzed. In the protonated water trimer, it was concluded that the H-bonded OH stretches strongly mix with combination bands and overtones that involve the motions of the hydronium core. The effects of tagging the protonated water tetramer with molecules of varying basicity was also investigated and the spectroscopic features during the proton transfer event were determined. Second-order perturbation theory was also used to calculate the vibrational spectrum of methyl hydroperoxide,… Advisors/Committee Members: Turro, Claudio (Advisor), McCoy , Anne (Advisor).

Subjects/Keywords: Chemistry; proton transfer; protonated water clusters; ion-water complexes; low frequency motions; OH stretches; H-bonding

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APA (6th Edition):

Dzugan, L. C. (2017). Theoretical Treatments of the Effects of Low Frequency Vibrations on OH Stretches in Molecules and Ion-Water Complexes that Undergo Large Amplitude Motions. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1492688748608717

Chicago Manual of Style (16th Edition):

Dzugan, Laura C. “Theoretical Treatments of the Effects of Low Frequency Vibrations on OH Stretches in Molecules and Ion-Water Complexes that Undergo Large Amplitude Motions.” 2017. Doctoral Dissertation, The Ohio State University. Accessed January 23, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492688748608717.

MLA Handbook (7th Edition):

Dzugan, Laura C. “Theoretical Treatments of the Effects of Low Frequency Vibrations on OH Stretches in Molecules and Ion-Water Complexes that Undergo Large Amplitude Motions.” 2017. Web. 23 Jan 2020.

Vancouver:

Dzugan LC. Theoretical Treatments of the Effects of Low Frequency Vibrations on OH Stretches in Molecules and Ion-Water Complexes that Undergo Large Amplitude Motions. [Internet] [Doctoral dissertation]. The Ohio State University; 2017. [cited 2020 Jan 23]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1492688748608717.

Council of Science Editors:

Dzugan LC. Theoretical Treatments of the Effects of Low Frequency Vibrations on OH Stretches in Molecules and Ion-Water Complexes that Undergo Large Amplitude Motions. [Doctoral Dissertation]. The Ohio State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1492688748608717

2. Bandyopadhyay, Biswajit. Infrared spectroscopy of cation-water complexes.

Degree: PhD, Chemistry, 2012, University of Georgia

Cation-water complexes are produced in a pulsed supersonic expansion source. Metal containing ions are produced by laser vaporization and the electric discharge technique is used for protonated complexes. Mass-selected ions are investigated with infrared laser photodissociation spectroscopy and the method of rare gas predissociation. The infrared spectra of singly charged metal cation-water complexes show red shifts in the O-H stretching frequencies compared to corresponding stretches of the isolated water molecule. The red shift is caused by polarization of water induced by the metal cation. The symmetric stretch gains more intensity than that of the asymmetric stretch in the metal cation-water systems. These effects are more prominent for the doubly charged ions. Partially resolved rotational structures for the Sc+(H2O)Ar and Cr+(H2O) complexes show that the H-O-H bond angle is larger than it is in the free water molecule. Multiple argons on Mn+(H2O) and multiple waters on Zn+(H2O) produce various low energy isomers. Zn+(H2O)Ar shows the largest red shift in the O-H stretching frequencies, whereas for Cr+(H2O)Ar this shift is smaller in magnitude. For doubly charged metal-water complexes, the O-H stretches are observed roughly at the same positions. Fragmentation and the spectral pattern shows that the coordination of M2+(M = Sc, V, Cr) is filled with six ligands. Mixed protonated complexes of water and nitrogen have H3O+(N2)n structures with a partial proton sharing interaction. The proton affinity of benzene is higher than that of water, but in the [H(C6H6)(H2O)]+ complex the proton resides closer to water as an effect of a favorable solvation energy. The shared proton stretch for this complex shows a larger red shift than the O-H stretches of H3O+. The larger [H(C6H6)m(H2O)n]+ sizes have structures of protonated water clusters solvated by benzene. The shared proton stretch shows a larger blue shift in [H(C6H6)(H2O)2]+ compared to the corresponding stretch of H5O2+-Ar due to a greater polarization effect of benzene. The preferential site of protonation is always on water in the systems with multiple benzenes. The strength of the π-hydrogen bonds decreases as the system is progressively solvated by benzene. The coordination of H5O2+ is completed with four benzenes. Advisors/Committee Members: Michael Duncan.

Subjects/Keywords: Spectroscopy; Infrared photodissociation; Metal ion solvation; Ion chemistry; Protonated complexes; Shared proton interactions; Density functional theory

…68 6. MIXED COMPLEXES OF PROTONATED BENZENE AND WATER ..................77 7… …136 A STRUCTURES AND VIBRATIONS OF PROTONATED BENZENEWATER COMPLEXES… …complexes.14 Recently, Johnson and coworkers studied hydronium and protonated water dimer with… …that of nitrogen (493.8 kJ/mol).66 The spectra of mixed protonated complexes of… …11 3. SINGLY CHARGED TRANSITION METAL CATIONWATER COMPLEXES… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Bandyopadhyay, B. (2012). Infrared spectroscopy of cation-water complexes. (Doctoral Dissertation). University of Georgia. Retrieved from http://purl.galileo.usg.edu/uga_etd/bandyopadhyay_biswajit_201205_phd

Chicago Manual of Style (16th Edition):

Bandyopadhyay, Biswajit. “Infrared spectroscopy of cation-water complexes.” 2012. Doctoral Dissertation, University of Georgia. Accessed January 23, 2020. http://purl.galileo.usg.edu/uga_etd/bandyopadhyay_biswajit_201205_phd.

MLA Handbook (7th Edition):

Bandyopadhyay, Biswajit. “Infrared spectroscopy of cation-water complexes.” 2012. Web. 23 Jan 2020.

Vancouver:

Bandyopadhyay B. Infrared spectroscopy of cation-water complexes. [Internet] [Doctoral dissertation]. University of Georgia; 2012. [cited 2020 Jan 23]. Available from: http://purl.galileo.usg.edu/uga_etd/bandyopadhyay_biswajit_201205_phd.

Council of Science Editors:

Bandyopadhyay B. Infrared spectroscopy of cation-water complexes. [Doctoral Dissertation]. University of Georgia; 2012. Available from: http://purl.galileo.usg.edu/uga_etd/bandyopadhyay_biswajit_201205_phd

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