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Full-Text Articles in Physics

Velocity-Map Imaging Photoelectron Spectroscopy Of Small Molecular Anions, Allan Maple De Oliveira Jan 2018

Velocity-Map Imaging Photoelectron Spectroscopy Of Small Molecular Anions, Allan Maple De Oliveira

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Gas phase anion photoelectron spectroscopy presents an opportunity for investigating molecules that are inaccessible by other experimental techniques, by providing data on the structure, reactivity and energetics of short-lived radicals and transition state species. Our recent development of a novel, plasma entrainment source of cold, weakly-bound anions opens a door to new exotic species to be investigated. In this thesis, I explore the capabilities of photoelectron spectroscopy and its application to small exotic molecular anions, while further developing and employing the novel dual-valve ion source.

The thesis begins with a brief history of photoelectron spectroscopy, followed by a description of ...


Photoelectron Spectroscopy Of Organic Aromatic Anions, Daniel John Nelson Jan 2017

Photoelectron Spectroscopy Of Organic Aromatic Anions, Daniel John Nelson

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Nelson, Daniel John (Ph.D. Chemical Physics)

Photoelectron Spectroscopy of Organic Aromatic Anions

Thesis directed by Professor W. Carl Lineberger

This dissertation reports and interprets the results of experiments in which photoelectron spectroscopy was performed on a variety of aromatic anions. In addition to these photoelectron studies, the results and conclusions of an experiment in which HCl is scattered off atomically flat Au (111) surfaces are also presented.

Photoelectron spectroscopy of the isomers of methylphenoxide reveals that these molecules display minimal vibrational excitation upon photodetachment, accessing the electronic ground and first excited state of the corresponding radicals. The photoelectron spectra ...


Rotational And Hyperfine Analysis Of Aus, Ian A. Wyse May 2016

Rotational And Hyperfine Analysis Of Aus, Ian A. Wyse

Macalester Journal of Physics and Astronomy

Gas phase diatomic gold sulfide, AuS, was analyzed using optical spectroscopy. High-resolution spectra were collected and characterized and a global fit of the A2+-X23/2 (0,0), B2-X23/2 (0,0), and C2Δ3/2-X21/2 (0,0) transitions at 15570 cm-1, 16290 cm-1, and 17670 cm-1 was compiled and resulted in rotational constant determinations for the A2+((2σ)1(4π)4), B2((2σ)2(4π)2(2σ*)1), and C2Δ3/2((2σ)2(4π)2(2σ*)1) upper ...


Pyrolysis And Spectroscopy Of Cyclic Aromatic Combustion Intermediates, Grant Thornton Buckingham Jan 2016

Pyrolysis And Spectroscopy Of Cyclic Aromatic Combustion Intermediates, Grant Thornton Buckingham

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

We have studied the pyrolysis of aromatic combustion intermediates using an array of detection techniques. The molecules investigated include cyclic aromatic molecules with hydrocarbon substituents (ethylbenzene, n-propylbenzene, isopropylbenzene, and styrene), oxygen-containing substituents (anisole and phenol), triply substituted systems (vanillin), resonance stabilized radicals (benzyl radical and tropyl radical) and phenyl radical. At the exit of a resistively heated micro-reactor (1 mm inner diameter, 3 cm long), the pyrolysis fragments are detected using photoionization mass spectrometry (PIMS), matrix isolation vibrational spectroscopy, microwave spectroscopy, tunable VUV synchrotron-based PIMS, and table-top VUV PIMS with photoelectron photoion coincidence spectroscopy (PEPICO). This array of detection methods ...


Excitonic States In Crystalline Organic Semiconductors: A Condensed Matter Approach, Lane Wright Manning Jan 2016

Excitonic States In Crystalline Organic Semiconductors: A Condensed Matter Approach, Lane Wright Manning

Graduate College Dissertations and Theses

In this work, a new condensed matter approach to the study of excitons based on crystalline thin films of the organic molecule phthalocyanine is introduced. The premise is inspired by a wealth of studies in inorganic semiconductor ternary alloys (such as AlGaN, InGaN, SiGe) where tuning compositional disorder can result in exciton localization by alloy potential fluctuations. Comprehensive absorption, luminescence, linear dichroism and electron radiative lifetime studies were performed on both pure and alloy samples of metal-free octabutoxy-phthalocyanine and transition metal octabutoxy-phthalocyanines, where the metal is Mn, Co, Ni, and Cu. Varying the ratios of the metal to metal-free phthalocyanines ...


Techniques In Molecular Spectroscopy: From Broad Bandwidth To High Resolution, Kevin C. Cossel Jan 2014

Techniques In Molecular Spectroscopy: From Broad Bandwidth To High Resolution, Kevin C. Cossel

Physics Graduate Theses & Dissertations

This thesis presents a range of different experiments all seeking to extended the capabilities of molecular spectroscopy and enable new applications. The new technique of cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) provides a unique combination of broad bandwidth, high resolution, and high sensitivity that can be useful for a wide range of applications. Previous demonstrations of CE-DFCS were confined to the visible or near-infrared and operated over a limited bandwidth: for many applications it is desirable to increase the spectral coverage and to extend to the mid-infrared where strong, fundamental vibrational modes of molecules occur. There are several key requirements ...


Electronic Photodissociation Spectroscopy Of Electrosprayed Anions, Jesse Cohen Marcum Jan 2011

Electronic Photodissociation Spectroscopy Of Electrosprayed Anions, Jesse Cohen Marcum

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Ionic compounds are ubiquitous and play central roles in a variety of chemical, physical, and biological processes. Due to the incredible complexity of many of these processes, it is advantageous to develop a detailed molecular-level description of ions as isolated species. This approach provides the ability to study the intrinsic properties of ions in the absence of perturbing effects from solvent and/or counterions. Additionally, such studies can be used to perform experiments on model systems in which ions serve as “molecular laboratories” for developing new insight to fundamental physical and chemical phenomena.

This thesis is comprised of work I ...


A Six-Dimensional H2–H2 Potential Energy Surface For Bound State Spectroscopy, Robert Hinde Jan 2008

A Six-Dimensional H2–H2 Potential Energy Surface For Bound State Spectroscopy, Robert Hinde

Chemistry Publications and Other Works

We present a six-dimensional potential energy surface for the (H2)2 dimer based on coupled-cluster electronic structure calculations employing large atom-centered Gaussian basis sets and a small set of midbond functions at the dimer’s center of mass. The surface is intended to describe accurately the bound and quasibound states of the dimers (H2)2, (D2)2, and H2–D2 that correlate with H2 or D2 monomers in the rovibrational levels (v, j) =(0,0), (0,2), (1,0), and (1,2). We employ a close-coupled approach to compute the energies of these ...


Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde Jan 2003

Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde

Chemistry Publications and Other Works

We present a model for the line shapes of infrared-active Q1(0) vibron bands observed in solid parahydrogen doped with low concentrations of spherical substitutional impurities. The line shapes are highly sensitive to the H2 vibrational dependence of the dopant–H2 interaction. When this vibrational dependence is strong, the dopant can trap the infrared-active vibron in its first solvation shell; in this case, the trapped vibron manifests itself in the absorption spectrum as a narrow feature to the red of the pure solid’s vibron band.


Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde Dec 2002

Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde

Robert Hinde

We present a model for the line shapes of infrared-active Q1(0) vibron bands observed in solid parahydrogen doped with low concentrations of spherical substitutional impurities. The line shapes are highly sensitive to the H2 vibrational dependence of the dopant–H2 interaction. When this vibrational dependence is strong, the dopant can trap the infrared-active vibron in its first solvation shell; in this case, the trapped vibron manifests itself in the absorption spectrum as a narrow feature to the red of the pure solid’s vibron band.


Probing Quantum Solvation With Infrared Spectroscopy: Infrared Activity Induced In Solid Parahydrogen By N2 And Ar Dopants, Robert Hinde Dec 2001

Probing Quantum Solvation With Infrared Spectroscopy: Infrared Activity Induced In Solid Parahydrogen By N2 And Ar Dopants, Robert Hinde

Robert Hinde

We present the first high-resolution study of the infrared (IR) absorption spectra of solid parahydrogen matrices containing low concentrations of N2 or Ar impurities. The spectra reveal dopant-induced absorption features that acquire IR activity through short-range isotropic vibrational transition dipole moments arising from dopant–H2 intermolecular interactions. These dopant-induced features provide new insights into the perturbation of the vibron bands of the H2 matrix by chemical impurities,and thus into the physics of solvation in a quantum solid.