Author: Eric Michael Ross
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
Book Description
Photoisomerization and Photodissociation Dynamics of Reactive Free Radicals
Author: Ryan Tyler Bise
Publisher:
ISBN:
Category :
Languages : en
Pages : 404
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 404
Book Description
Photodissociation Dynamics of Free-radicals
Author: Eric Michael Ross
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
Book Description
Coincidence and Noncoincidence Studies of the Photodissociation Dynamics of Free Radicals
Author: Ann Elise Faulhaber
Publisher:
ISBN:
Category :
Languages : en
Pages : 238
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 238
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.
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.
Photodissociation Dynamics of Free Radicals Using High-n Rydberg Atom Time-of-flight Technique
Author: Yu Song
Publisher:
ISBN: 9781124563251
Category : Molecular dynamics
Languages : en
Pages : 253
Book Description
The first chapter discusses the photodissociation dynamics as well as its experimental methodology. The experimental setup of the HRTOF technique is explained in detail.
Publisher:
ISBN: 9781124563251
Category : Molecular dynamics
Languages : en
Pages : 253
Book Description
The first chapter discusses the photodissociation dynamics as well as its experimental methodology. The experimental setup of the HRTOF technique is explained in detail.
UV-photodissociation Dynamics of Small Molecules and Free Radicals Studied by High-n Rydberg H-Atom Time of Flight Spectroscopy
Author: Gabriel Alejandro Amaral
Publisher:
ISBN:
Category : Molecular dynamics
Languages : en
Pages : 406
Book Description
Publisher:
ISBN:
Category : Molecular dynamics
Languages : en
Pages : 406
Book Description
Photodissociation Spectroscopy and Dynamics of Free Radicals, Clusters, and Ions
Author: Hyeon Choi
Publisher:
ISBN:
Category :
Languages : en
Pages : 340
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 340
Book Description
Photodissociation Dynamics of the NCO Free Radical
Author: Stephen Gómez Díaz
Publisher:
ISBN:
Category :
Languages : en
Pages : 390
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 390
Book Description
Photodissociation Dynamics and Spectroscopy of Free Radical Combustion Intermediates
Author: David Lewis Osborn
Publisher:
ISBN:
Category :
Languages : en
Pages : 842
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 842
Book Description
Photodissociaion Dynamics of Neutral Free Radicals
Author: Bogdan Negru
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
Photofragment translational spectroscopy was used to study the photodissociation dynamics of the phenyl and tert-butyl radicals. These radicals were produced in a collisionless environment from the flash pyrolysis of the appropriate precursor, nitrosobenzene for phenyl and azo-tert-butane for the tert-butyl radical. The photodissociation dynamics of the phenyl radical (C6H5) were investigated at 248 and 193 nm. At 248 nm, the only dissociation products observed were from hydrogen atom loss, attributed primarily to H + o-C6H4 (ortho-benzyne). The observed translational energy distribution was consistent with statistical decay on the ground state surface. At 193 nm, dissociation to H + C6H4 and C4H3 + C2H2 was observed. The C6H4 fragment can be either o-C6H4 or l-C6H4 resulting from opening of the phenyl ring. The C4H3 + C2H2 products dominate over the two H loss channels. Attempts to reproduce the observed branching ratio by assuming ground state dynamics were unsuccessful. This discord, between the experimentally observed branching ratio and the theoretically predicted branching ratio led us to reinvestigate the dissociation dynamics of the phenyl radical at 193 nm, while producing the radical under different source conditions. The photodissociation dynamics of the tert-butyl radical (t-C4H9) were investigated at 248 nm. Two distinct channels of approximately equal importance were identified: dissociation to H + 2-methylpropene (C4H8), and CH3 + dimethylcarbene (C3H6). Neither the translational energy distributions that describe these two channels nor the product branching ratio are consistent with statistical dissociation on the ground state, and instead favor a mechanism taking place on excited state surfaces. The studies presented in this dissertation show that although hydrogen atom loss is sometimes expected to be the only major dissociation pathway in the photodissociation of hydrocarbon radicals this is not always a justified assumption.
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
Photofragment translational spectroscopy was used to study the photodissociation dynamics of the phenyl and tert-butyl radicals. These radicals were produced in a collisionless environment from the flash pyrolysis of the appropriate precursor, nitrosobenzene for phenyl and azo-tert-butane for the tert-butyl radical. The photodissociation dynamics of the phenyl radical (C6H5) were investigated at 248 and 193 nm. At 248 nm, the only dissociation products observed were from hydrogen atom loss, attributed primarily to H + o-C6H4 (ortho-benzyne). The observed translational energy distribution was consistent with statistical decay on the ground state surface. At 193 nm, dissociation to H + C6H4 and C4H3 + C2H2 was observed. The C6H4 fragment can be either o-C6H4 or l-C6H4 resulting from opening of the phenyl ring. The C4H3 + C2H2 products dominate over the two H loss channels. Attempts to reproduce the observed branching ratio by assuming ground state dynamics were unsuccessful. This discord, between the experimentally observed branching ratio and the theoretically predicted branching ratio led us to reinvestigate the dissociation dynamics of the phenyl radical at 193 nm, while producing the radical under different source conditions. The photodissociation dynamics of the tert-butyl radical (t-C4H9) were investigated at 248 nm. Two distinct channels of approximately equal importance were identified: dissociation to H + 2-methylpropene (C4H8), and CH3 + dimethylcarbene (C3H6). Neither the translational energy distributions that describe these two channels nor the product branching ratio are consistent with statistical dissociation on the ground state, and instead favor a mechanism taking place on excited state surfaces. The studies presented in this dissertation show that although hydrogen atom loss is sometimes expected to be the only major dissociation pathway in the photodissociation of hydrocarbon radicals this is not always a justified assumption.