Resolving the turnover of temperature dependence of the reaction rate in barrierless isomerization

Article Abstract:

The temperature dependence of the barrierless cis-trans isomerization reaction in the excited state of 1,1'-diethyl-4,4'-cyanine was investigated. Measurement of transient absorption kinetics and transient absorption spectra at different temperatures and viscosities showed dynamic information on the isomerization process of constant viscosity. Results suggest a crossover of reaction rate from a negative temperature dependence at low viscosities to a positive temperature dependence at higher viscosities. This is due to the competition between the two processes following excitation.

Analysis, Temperature measurements, Temperature measurement, Isomerization, Excited state chemistry, Cyanides

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Dynamics of excited states of the carotenoid peridinin in polar solvents: dependence on excitation wavelength, viscosity, and temperature

Article Abstract:

Several equlibria occur between Fe(super 3+), Fe(super 2+), Cl(super -), the neutral carotenoid, and its radical cation and dication in the oxidation of carotenoids, ethyl all-trans-8'-apo-beta-caroten-8'-oate and all-trans-beta-carotene, with ferric chloride. The radical cation and dication were found to abstract an electron from Fe(super 2+) and in the presence of air, a stable product is formed in high yield.

Science & research, Carotenoids, Oxidation-reduction reaction, Oxidation-reduction reactions, Chemistry, Physical and theoretical, Physical chemistry, Chemical properties

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