12 documents found, page 1 of 2
Solution and surface photochemistry of fenarimol: A comparative study
Silva, José P. da; Mateus, M. Conceição D. A.; Silva, Abílio M. da; Ferreira, Luís F. Vieira; Burrows, Hugh D.The photochemistry of the pesticide fenarimol was studied in methanol and on a cellulose surface. The ground state absorption and fluorescence spectra are similar in solution and at the solid/gas interface. Room temperature phosphorescence emission was observed in cellulose. Transient absorption of fenarimol and of its chromophoric units, chlorobenzene and pyrimidine, showed a common absorption band centered at...
Solution and surface photochemistry of fenarimol: a comparative study
Silva, José P. da; Mateus, Maria Da Conceição; Silva, Abílio M. da; Ferreira, Luís F. Vieira; Burrows, Hugh D.The photochemistry of the pesticide fenarimol was studied in methanol and on a cellulose surface. The ground state absorption and fluorescence spectra are similar in solution and at the solid/gas interface. Room temperature phosphorescence emission was observed in cellulose. Transient absorption of fenarimol and of its chromophoric units, chlorobenzene and pyrimidine, showed a common absorption band centered at...
Photolysis of 4-chloroanisole in the presence of oxygen: formation of the 4-met...
Silva, José P. da; Ferreira, Luís F. Vieira; Machado, Isabel Ferreira; Silva, Abílio M. daThe photochemistry of 4-chloroanisole was studied in cyclohexane, with and without molecular oxygen. The triplet state is the main transient in argon purged solutions. In air equilibrated conditions the triplet state was not detected and a new broad absorption band was observed above 450 nm. This absorption was assigned to the 4-methoxyphenylperoxyl radical. The formation of phenylperoxyl radicals after direct ...
Aqueous photochemistry of pesticides triadimefon and triadimenol
Silva, José P. da; Ferreira, Luís F. Vieira; Silva, Abílio M. daThe photochemistry of pesticides triadimefon and triadimenol was studied in aqueous solution and in methanol/water mixtures, in controlled and natural conditions. The photodegradation kinetics and product distribution are strongly dependent on the solvent and on the irradiation wavelength. The degradation rates are faster at 254 nm than at 313 nm. The kinetics is faster in water than methanol. Direct photoreact...
Photochemistry of 4-chlorophenol on cellulose and silica
Silva, José P. da; Ferreira, Luís F. Vieira; Silva, Abílio M. da; Oliveira, A. S.The photochemistry of 4-chlorophenol (4-CP) was studied on silica and cellulose, using time-resolved diffuse reflectance techniques and product degradation analysis. The results have shown that the photochemistry of 4-CP depends on the support, on the concentration, and also on the sample preparation method. Transient absorption and photoproduct results can be understood by assuming the formation of the carbene...
Fenarimol solar degradation pathways and photoproducts in aqueous solution
Mateus, M. Conceição D. A.; Silva, Abílio M. da; Burrows, Hugh D.http://www.sciencedirect.com/science/article/B6V74-44X00X6-2/1/82feeddfa7673b496683c783fbe3fb85
A comparative study of the photophysics and photochemistry of 4-chlorophenol ad...
Da Silva, José Paulo; Ferreira, Luís F. Vieira; Silva, Abílio M. da; Oliveira, A. S.The photochemistry and photophysics of 4-chlorophenol (4-CP) were studied onto two model solid supports, silicalite and beta-cyclodextrin (beta-Cl)), using time resolved diffuse reflectance techniques and product degradation analysis. The results have shown that the photochemistry and photophysics of 4-CP are different from solution and depend on the solid. Ground state diffuse reflectance and time resolved lum...
Dissipation of triadimefon on the solid/gas interface
Silva, José P. da; Silva, Abílio M. da; Khmelinskii, IgorThe dissipation or triadimefon, as pure solid and in the Bayleton 5 commercial formulation, was studied under controlled and natural conditions. Volatilization and photodegradation were shown to be the main dissipation processes. The volatilization results can be described by an empirical model assuming exponential decay of the volatilization rate. The filler of the commercial formulation is determinant for the...
Photophysics and photochemistry of azole fungicides: triadimefon and triadimenol
Silva, José P. da; Silva, Abílio M. da; Khmelinskii, Igor; Martinho, J. M. G.; Ferreira, Luís F. VieiraPhotophysics and photochemistry of pesticides triadimefon {1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl) butanone} and triadimenol {1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl) butan-2-ol} were studied in the solution. The excited singlet states were identified by comparison with the absorption spectra of adequate model compounds, in several solvents. The first excited singlet state o...
Kinetics of photodegradation of the fungicide fenarimol in natural waters and i...
Mateus, M. Conceição D. A.; Silva, Abílio M. da; Burrows, Hugh D.The rate of photodegradation of the fungicide fenarimol ([alpha]-(2-chlorophenyl)-[alpha]-(4-chlorophenyl)-5-pyrimidine-methanol) by solar radiation has been studied in natural waters with different salinities. Photodegradation rates and quantum yields are found to decrease with increasing salinity.; http://www.sciencedirect.com/science/article/B6V73-3YF3VXJ-6/1/852ccb9d579f1edc3ac6d240675bf88b