Author: Niels E. SveumPublisher:
ISBN:
Category :
Languages : en
Pages : 380
Book Description
Photodissociation Dynamics Studies Via Photofragment Translational Spectroscopy
Author: Niels E. SveumPhotodissociation Dynamics and Spectroscopy of Free Radical Combustion Intermediates
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 422
Book Description
The photodissociation spectroscopy and dynamics of free radicals is studied by the technique of fast beam photofragment translational spectroscopy. Photodetachment of internally cold, mass-selected negative ions produces a clean source of radicals, which are subsequently dissociated and detected. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states of the radical. In addition, the photodissociation dynamics, product branching ratios, and bond energies are probed at fixed photon energies by measuring the translational energy, P(E{sub T}), and angular distribution of the recoiling fragments using a time- and position-sensitive detector. Ab initio calculations are combined with dynamical and statistical models to interpret the observed data. The photodissociation of three prototypical hydrocarbon combustion intermediates forms the core of this work.
Investigations of Two- and Three-Body Molecular Photodissociation Dynamics by Fast Beam Photofragment Translational Spectroscopy
Author: Aaron Woods HarrisonStudies of Photofragment Translational Spectroscopy
Author: Scott Johnathan GoncherPublisher:
ISBN:
Category :
Languages : en
Pages : 280
Book Description
Photoisomerization and Photodissociation Dynamics of Reactive Free Radicals
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 198
Book Description
The photofragmentation pathways of chemically reactive free radicals have been examined using the technique of fast beam photofragment translational spectroscopy. Measurements of the photodissociation cross-sections, product branching ratios, product state energy distributions, and angular distributions provide insight into the excited state potential energy surfaces and nonadiabatic processes involved in the dissociation mechanisms. Photodissociation spectroscopy and dynamics of the predissociative {tilde A}2A1 and {tilde B}2A2 states of CH3S have been investigated. At all photon energies, CH3 + S(3P{sub j}), was the main reaction channel. The translational energy distributions reveal resolved structure corresponding to vibrational excitation of the CH3 umbrella mode and the S(3P{sub j}) fine-structure distribution from which the nature of the coupled repulsive surfaces is inferred. Dissociation rates are deduced from the photofragment angular distributions, which depend intimately on the degree of vibrational excitation in the C-S stretch. Nitrogen combustion radicals, NCN, CNN and HNCN have also been studied. For all three radicals, the elimination of molecular nitrogen is the primary reaction channel. Excitation to linear excited triplet and singlet electronic states of the NCN radical generates resolved vibrational structure of the N2 photofragment. The relatively low fragment rotational excitation suggests dissociation via a symmetric C{sub 2V} transition state. Resolved vibrational structure of the N2 photofragment is also observed in the photodissociation of the HNCN radical. The fragment vibrational and rotational distributions broaden with increased excitation energy. Simple dissociation models suggest that the HNCN radical isomerizes to a cyclic intermediate (c-HCNN) which then dissociates via a tight cyclic transition state. In contrast to the radicals mentioned above, resolved vibrational structure was not observed for the ICNN radical due to extensive fragment rotational excitation, suggesting that intermediate bent states are strongly coupled along the dissociation pathway. The measurements performed in this Thesis have additionally refined the heats of formation and bond dissociation energies of these radicals and have unambiguously confirmed and added to the known electronic spectroscopy.
UV-photodissociation Dynamics of Small Molecules and Free Radicals Studied by High-n Rydberg H-Atom Time of Flight Spectroscopy
Author: Gabriel Alejandro AmaralPublisher:
ISBN:
Category : Molecular dynamics
Languages : en
Pages : 406
Book Description
Photodissociation Dynamics and Spectroscopy of Small, Isolated, Vibrationally Excited Molecules
Author: J. Matthew HutchisonPublisher:
ISBN:
Category :
Languages : en
Pages : 296
Book Description
Dynamics of Molecular Photodissociation Studied Using Coherent Vacuum Ultraviolet
Author: Michael Aaron TodtPhotodissociation Dynamics
Author: Reinhard SchinkePublisher: Cambridge University Press
ISBN: 9780521484145
Category : Science
Languages : en
Pages : 446
Book Description
Photodissociation induced by the absorption of single photons permits the detailed study of molecular dynamics such as the breaking of bonds, internal energy transfer and radiationless transitions. The availability of powerful lasers operating over a wide frequency range has stimulated rapid development of new experimental techniques which make it possible to analyse photodissociation processes in unprecedented detail. This text elucidates the achievements in calculating photodissociation cross-sections and fragment state distributions from first principles, starting from multi-dimensional potential energy surfaces and the Schrödinger equation of nuclear motion. Following an extended introduction in which the various types of observables are outlined, the book summarises the basic theoretical tools, namely the time-independent and the time-dependent quantum mechanical approaches as well as the classical picture of photodissociation. The discussions of absorption spectra, diffuse vibrational structures, the vibrational and rotational state distributions of the photofragments form the core of the book. More specific topics such as the dissociation of vibrationally excited molecules, emission during dissociation, or nonadiabatic effects are also discussed. It will be of interest to graduate students and senior scientists working in molecular physics, spectroscopy, molecular collisions and molecular kinetics.
Photodissociation of Atmospherically Relevant Molecules Investigated by Photofragment Translational Spectroscopy
Author: Marie-Anne ThelenPublisher:
ISBN:
Category : Photodissociation
Languages : en
Pages : 140
Book Description