Author: Xin HuangPublisher:
ISBN:
Category :
Languages : en
Pages : 212
Book Description
Laser Induced Fluorescence Studies of the Dynamics of Gas Phase Reactions and Photodissociations
Author: Xin HuangLaser-Induced Fluorescence Studies of Reaction Dynamics
Author: AListair Malcolm Laing IrvinePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Photofragmentation Spectroscopy and Photodissociation Dynamics of Polyatomic Molecules
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 23
Book Description
The detailed reaction dynamics of several gas phase polyatomic systems has been established in this research at the Department of Chemistry at the University of Puerto Rico. Real time dynamics of sulfur monoxide photoelimination reactions have been studied by laser induced fluorescence spectroscopy of the nascent SO fragment on the B(3) sigma( - ) - X(3) sigma( - ) transition in the region of 237-310 nm. The following group of molecules has been studied: Sulfur dioxide (SO2), the thionyl halides (SOX2, where X=F, Cl or Br), dimethyl sulfoxide ((CH3)2SO!, ethylene episulfoxide ((CH2)2SO), trimethylene sulfoxide ((CH2)3SO), tetramethylene sulfoxide ((CH2)4SO), and thionyl aniline (C6H5NSO!. In all of these experiments, the parent molecule is irradiated with an excimer laser (either 193 or 248 nm) and the energy disposal into the nascent SO photofragment is determined, and used as a mechanistic probe. A broad picture of sulfur monoxide photoelimination reactions emerges from this work. A general procedure to evaluate the rotational state population distributions of the nascent photofragments from the photodissociation of polyatomic molecules has been implemented with the use of a kinematic distribution function. Numerical evaluations of rotational state population distributions of diatomic photofragments from photodissociation of the general class of triatomic molecules are presented. In a second area, the photophysics and photochemistry of the vinoxy radical were investigated. Fluorescence decay rates were determined in the presence of twelve collision partners: He, Ar, N2, O2, CO, H2, HCl, CO2, N2O, C2H4, SF6 and CH3OCH=CH2. The measured electronic quenching cross-sections vary from 0.01 - 66.5 A2. jg p2.
Photophysics and Photochemistry of Ions and Complexes in the Gas Phase
Author: Huihui YaoPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This thesis focuses on studying the intrinsic properties of some fluorescent dyes and their complexes in the gas phase, while eliminating external interactions with solvent molecules. A novel setup, which couples a trapping mass spectrometer to lasers as excitation sources, is used to perform photodissociation and fluorescence experiments on isolated, mass-selected ions. The common fluorescent dye fluorescein and halogenated fluorescein ions in the gas phase show very different fluorescence and photodissociation properties than in solution: the most fluorescent charge state in solution, the dianion, does not emit detectable fluorescence in the gas phase; in addition, the most stable monoanionic form of fluorescein in the gas phase has a protonated carboxyphenol pendant group rather than protonation on the hydroxyl group of the chromophore as found in solution. Building blocks of xanthene dyes, pyronin Y and pyronin B ions, exhibit much longer intrinsic fluorescence lifetimes in the gas phase than in solution, mostly owing to a substantial decrease in nonradiative decay rates. Gas-phase studies on more complex systems are done on gaseous noncovalent complexes of pyronin Y with a macrocyclic molecule cucurbit[7]uril and polypeptides covalently labelled by a BoDIPY dye and quencher tryptophan. Fluorescence properties of the gaseous noncovalent pyronin Y and cucurbit[7]uril complex suggest interaction of these dyes with macrocycle cucurbit[7]uril plays a relatively minor role in their photophysics compared to interactions with solvent molecules. Fluorescence properties of dye labeled polypeptides show that quenching is more sensitive to the type of repeating unit, alanine or glycine, than the presence (or location) of quencher tryptophan. Taken together, this thesis presents benchmark results on the intrinsic photophysics of key fluorophore classes and lays essential groundwork for the use fluorescence in investigations of intrinsic properties of more complex systems such as biomolecules. Overall, the work reported in this thesis serves as a proof-of-concept work demonstrating the applicability of coupling modified trapping mass spectrometer and optical spectroscopy set-ups to study the intrinsic properties of ions.
Laser Induced Fluorescence Studies in the Gas Phase
Author: Christopher Guy AtkinsPublisher:
ISBN:
Category : Fluorescence
Languages : en
Pages : 0
Book Description
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 846
Book Description
Energy Research Abstracts
Author: Laser Flash Photolysis Studies of Some Gas Phase Reactions of Atmospheric Interest
Author: Zhijun ZhaoPublisher:
ISBN:
Category : Dynamics
Languages : en
Pages :
Book Description
Radical reactions play central roles in regulating regional air quality and global climate. Some potentially important gas phase radical reactions are being investigated in this research project, including Cl reactions with acetone, butanone, 3-pentanone, pyridine, and dimethyl selenide (DMSe), HO2 complex formation and dissociation with formic and acetic acids, and reactive and non-reactive quenching of O(1D) by the potent greenhouse gases SO2F2, NF3, and SF5CF3. The involved radicals are generated by laser flash photolysis (LFP). Temporal profiles of either the radical reactant or a product are monitored in "real time" using atomic resonance fluorescence spectroscopy (RF), time-resolved UV-visible absorption spectroscopy (TRUVVAS), or tunable diode laser absorption spectroscopy (TDLAS), allowing kinetic and mechanistic information of these reactions to be obtained. These studies provide new knowledge of the investigated radical reactions and facilitate a better understanding of their significance in atmospheric chemistry.
Chemical and Biochemical Applications of Lasers V5
Author: C. Bradley MoorePublisher: Elsevier
ISBN: 0323157270
Category : Science
Languages : en
Pages : 294
Book Description
Chemical and Biological Applications of Lasers, Volume V focuses on the laser applications in photochemistry and spectroscopy. This book examines the spectroscopic detection of single atoms and explores the purification of industrial chemicals. Organized into seven chapters, this volume starts with an overview of the methods developed for laser detection of single atoms, including fluorescence, photoionization, photodeflection, and their combinations. This text then discusses the methods of high resolution spectroscopy, which provide detailed information on molecular structure and reaction kinetics studies. Other chapters review several laser photodissociation studies, which explain dissociation dynamics. This book discusses as well the possibilities for selective photochemical reactions and examines the potential of lasers for practical application in chemical processing. The final chapter considers the various metals that can undergo a photochemical change in oxidation state in ordinary solvents. This book is a valuable resource for physicists, chemists, electrochemists, photochemists, electrical engineers, and chemical engineers.
Author: Martin Thomas Zanni