Kinetics of Triplet Sublevel Selective Photochemical Reactions in the Solid State

Abstract A detailed description of the overall kinetics of photochemical reactions has to deal with photo-physical activation and de-activation rates as well as with true photochemical rates. Based on the hypothesis that for photoreactions involving the lowest excited triplet state the chemical reaction rates of the individual triplet zero-field levels have different values, a method is presented for the evaluation of these rates from bulk measurements under steady state illumination conditions. The complications arising from the detection of solid state reactions are discussed, and a simple solution is given, illustrated by a numerical example.

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Solid-State Reactions in Model Oxide Systems

MRS Proceedings ◽

10.1557/proc-453-695 ◽

1996 ◽

Vol 453 ◽

Author(s):

Matthew T. Johnson ◽

Paul G. Kotula ◽

Ryan S. Thompson ◽

C. Barry Carter

Keyword(s):

Thin Films ◽

Solid State ◽

Reaction Rates ◽

Oxide System ◽

Solid State Reactions ◽

Diffusion Control ◽

Phase Boundaries ◽

Oxide Systems ◽

Fe Oxide ◽

Kinetics Of

AbstractThe kinetics of thin-film solid-state reactions have been investigated in two model spinel forming oxide systems, NiO/Al2O3 and MgO/Fe2O3. In the NiO/Al2O3 system, thin-films of epitactic NiO were reacted with (0001), , and orientated Al2O3 (corundum). The kinetics of the spinel forming reaction for this system were found to be linear-parabolic in nature. Additionally, it was found that the kinetics of the spinel-forming reaction varied by nearly two orders of magnitude between the fastest and slowest diffusion couples. The substrate determines the orientation of the overlayers and thereby the structure of the phase boundaries. In the MgO/Fe-oxide system, thin films of epitactic Fe oxide were reacted with {001} MgO. The kinetics of this spinel forming reaction were parabolic in nature, indicative of diffusion control. In contrast to the N1O/Al2O3 system, the movement of phase boundaries are not the step controlling the reaction rate, but rather the diffusion of one of the cations across the reaction layer. In comparing the reaction rates for the two systems the activation energy for the formation of the spinel product in the MgO/Fe-oxide system was found to be almost a factor of 4 lower in comparison to the NiO/Al2O3 system.

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Kinetics of esterification of monoisopropylphenols with phosphoryl trichloride

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19891311 ◽

1989 ◽

Vol 54 (5) ◽

pp. 1311-1317

Author(s):

Miroslav Magura ◽

Ján Vojtko ◽

Ján Ilavský

Keyword(s):

Liquid Phase ◽

Rate Constants ◽

Reaction Rates ◽

Activation Energies ◽

The Individual ◽

Kinetics Of

The kinetics of liquid-phase isothermal esterification of POCl3 with 2-isopropylphenol and 4-isopropylphenol have been studied within the temperature intervals of 110 to 130 and 90 to 110 °C, respectively. The rate constants and activation energies of the individual steps of this three-step reaction have been calculated from the values measured. The reaction rates of the two isomers markedly differ: at 110 °C 4-isopropylphenol reacts faster by the factors of about 7 and 20 for k1 and k3, respectively. This finding can be utilized in preparation of mixed triaryl phosphates, since the alkylation mixture after reaction of phenol with propene contains an excess of 2-isopropylphenol over 4-isopropylphenol.

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Electric-Field Effects on Reactions Between Oxides

MRS Proceedings ◽

10.1557/proc-481-303 ◽

1997 ◽

Vol 481 ◽

Author(s):

Matthew T. Johnson ◽

Shelley R. Gilliss ◽

C. Barry Carter

Keyword(s):

Solid State ◽

Electric Field ◽

Elevated Temperatures ◽

Ionic Current ◽

Reaction Rates ◽

Solid State Reactions ◽

Interfacial Stability ◽

Electric Field Effects ◽

Thin Film Diffusion ◽

Microscopy Techniques

ABSTRACTThin films of In2O3 and Fe2O3 have been deposited on (001) MgO using pulsed-laser deposition (PLD). These thin-film diffusion couples were then reacted in an applied electric field at elevated temperatures. In this type of solid-state reaction, both the reaction rate and the interfacial stability are affected by the transport properties of the reacting ions. The electric field provides a very large external driving force that influences the diffusion of the cations in the constitutive layers. This induced ionic current causes changes in the reaction rates, interfacial stability and distribution of the phases. Through the use of electron microscopy techniques the reaction kinetics and interface morphology have been investigated in these spinel-forming systems, to gain a better understanding of the influence of an electric field on solid-state reactions.

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The kinetics of solid-state reactions toward consensus, Part 2: Fitting kinetics data in dynamic conventional thermal analysis

International Journal of Chemical Kinetics ◽

10.1002/kin.10028 ◽

2002 ◽

Vol 34 (3) ◽

pp. 193-208 ◽

Cited By ~ 16

Author(s):

A. Ortega

Keyword(s):

Thermal Analysis ◽

Solid State ◽

Solid State Reactions ◽

Kinetics Of

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Solid-State Reactions in Multilayer Ni/Ti Thin Film Composites

MRS Proceedings ◽

10.1557/proc-205-215 ◽

1990 ◽

Vol 205 ◽

Cited By ~ 1

Author(s):

Gillian E. Winters ◽

K.M. Unruh ◽

C.P. Swann ◽

M.E. Patt ◽

B.E. White ◽

...

Keyword(s):

Solid State ◽

Solid State Reactions ◽

Metastable Solid Solution ◽

State Transformation ◽

Solid State Transformation ◽

Scanning Calorimetry ◽

The Individual ◽

Thin Film Composites ◽

Film Composites ◽

Rf Sputter Deposition

AbstractMultilayer films, consisting of alternating layers of crystalline Ni and Ti, have been prepared by RF sputter deposition over a range of modulation wavelengths corresponding to an overall composition of Ni50Ti50. These films have been characterized by xray diffraction and Rutherford backscattering measurements. The solid-state transformation by interdiffusional mixing of the individual layers has been directly studied by differential scanning calorimetry and correlated with structural measurements. These measurements indicate that the solid-state reaction of Ni and Ti multilayers proceeds through the formation of a metastable solid solution of Ti in Ni followed by the formation of intermetallic equilibrium compounds. No direct calorimetric or structural evidence for the formation of an amorphous Ni-Ti phase has been found in these samples.

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