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![Dynamics of oxygen and fluorine atom reactions with halogen, interhalogen, alkyl and allyl iodide molecules için kapak resmi Dynamics of oxygen and fluorine atom reactions with halogen, interhalogen, alkyl and allyl iodide molecules için kapak resmi](/client/assets/d79c3e4af2b6d196/ctx/images/no_image.png)
Dynamics of oxygen and fluorine atom reactions with halogen, interhalogen, alkyl and allyl iodide molecules
Başlık:
Dynamics of oxygen and fluorine atom reactions with halogen, interhalogen, alkyl and allyl iodide molecules
Yazar:
White, Richard William Peter, author.
ISBN:
9780438084124
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (219 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
The use of the "Athena" crossed molecular beam apparatus for studying a range of atomic and molecular reactions has been outlined. The reactions of oxygen atoms with C2H5I, (CH3)2CHI, (CH3)3CI and C3H5I molecules have been studied at an initial translational energy E =36 kJ/mol. The propensity toward backward scattering and the fraction of the available energy disposed into product translation both increase along the series of reactions. The trend is attributed to reactions at small impact parameters b<2.5A over a weakly attractive triplet potential energy surface, which splits into 3A' and 3A" Renner-Teller components in bent OIR configurations. Translational energy threshold functions have been determined for the endoergic reactions of F2 molecules with CH3I, C2H5I, C3H7I, (CH3)2CHI, (CH3)3CI and C3H5I molecules. The threshold energies have been used to determine the stabilities of the FIR complex intermediates formed from the reactions of atomic fluorine with the same set of organic iodides. The FIR dissociation energies are approximately constant, Dq(F-IR) =115+/-5 kJ/mol with respect to the reactants F+IR, but are found to vary with respect to the IF+R products. The FI-R dissociation energy is 70+/-5 kJ/mol for the alkyl iodides, but is much lower for allyl iodide at 23+/-10 kJ/mol. Lifetimes of the FIR complexes are calculated from RRKM microcanonical transition-state theory, and compared with the values determined from the angular distributions measured from the atomic fluorine reactions at E =38 kJ/mol. The importance of low frequency transitional vibrational modes, which alter significantly from complex to transition-state, is demonstrated by approximate comparison of theoretical and experimental lifetimes. The reactions of fluorine atoms with Br2 and IGl molecules have been studied at an initial translational energy E =15 kJ/mol. Both the reactions show peaking in the forward direction, which is more pronounced for Bt2 than for ICl. Approximately half the energy available is disposed into product translation for Br2, whereas the product translational energy distribution for ICl accords with the microcanonical prior distribution. The observations from the F+Br2 reaction are attributed to migratory trajectories from large impact parameter collisions in which the F atom reacts with the more distant of the bromine atoms, lying in the forward hemisphere. The more isotropic wide angle scattering arises from direct trajectories, reacting with the nearer Br atom. Migration is promoted by charge transfer in an F'Br2+ species, which stabilises the potential energy surface. In contrast, the F+ICl potential energy surface involves an "FICl hollow" equal in depth to the total energy available to products, ~70 kJ/mol. The reaction proceeds via a short-lived collision complex, with migratory trajectories inducing enhanced product translation when the F atom intrudes between the separating I and Cl atoms. In both reactions, the dynamical behaviour reflects the existence of two accessible configurations on the potential energy surface; a slightly bent F-Br-Br, F-I-Cl configuration with an interbond angle -140°, and a strongly bent configuration ~90° for FICl, which becomes isosceles triangular for FBr2- The broad results from the oxygen atom work have been used for a sensitivity study on the U.K.A.E.A / S.R.D. Advanced Gas-cooled nuclear reactor program, RADCAL. This code simulates the speciation and location of iodine in the cooling circuit of the reactor. Predictions were made for operating and shut-down reactor scenarios, and showed the iodine chemistry to be most sensitive to the O+RI rate constant when the reactor is at a low power condition. The kinetic model needs to be reviewed in the light of the new results.
Notlar:
School code: 1543
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(686896.1) | 686896-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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