Zobrazeno 1 - 10
of 122
pro vyhledávání: '"MICHAEL KASHA"'
Publikováno v:
Photochemistry and Photobiology. 91:576-585
Trace quantities of hydrogen-bonding impurities in otherwise highly purified and dried glassy hydrocarbon matrices at 77 K can modify the relative triplet state energy levels, and hence the photophysical properties of two aromatic ketones, xanthone a
Autor:
Michael Kasha
Publikováno v:
Radiation Research. 178:AV27-AV34
Energytransferphenomenacontinuetofascinatethebiologist, chemist, and physicist, and the literature contains numerous experiments designed to demonstrate the presence of excitation energy transfer. At the present stage of development of the theoryofsu
Publikováno v:
Proceedings of the National Academy of Sciences. 101:419-422
A theoretical analysis of the double proton transfer (PT) in a hydrogen-bonded N-heterocyclic base pair is presented. The calculated (time-dependent density functional theory) double PT barrier calculated for the concerted process of the 7-azaindole
Publikováno v:
Proceedings of the National Academy of Sciences. 99:5799-5803
A mechanism is proposed for the formation in gas phase, during a short time, of the delicately symmetrical coplanar C 2h classic 7-azaindole (7AI) doubly hydrogen-bonded dimer. Of the five card-pack or otherwise random geometry structures most likely
Autor:
Michael Kasha, Javier Catalán† and
Publikováno v:
Scopus-Elsevier
Photophysical research on the experimental and theoretical bases for the biprotonic transfer in the doubly-H-bonded dimer of 7-azaindole (7AI) is reported. The spectroscopic properties of the 7AI monomer, the normal-tautomer dimer, and the proton-tra
Publikováno v:
Scopus-Elsevier
In this Letter we consider the second laser-pulse time delay experiments of Castleman and co-workers [D.E. Folmer, L. Poth, E.S. Wisniewski, A.W. Castleman, Jr., Chem. Phys. Lett. 287 (1998) 1; D.E. Folmer, E.S. Wisniewski, S.M. Hurley, A.W. Castlema
Publikováno v:
International Journal of Quantum Chemistry. 77:118-127
Study of the chemically produced anionic and cationic species of the heterocyclics 7-azaindole (7-AI) and 1-H-pyrrolo[3,2-h]quinoline (1-HPQ) in 298 K solution spectroscopy displays a striking coincidence of the anion/cation spectra for each. A hybri
Publikováno v:
The Journal of Physical Chemistry A. 103:2467-2475
The molecule 1-H-pyrrolo[3,2-h]quinoline (1-HPQ) (alternatively pyrido[3,2-g]indole) and its 1-methyl derivative (1-MPQ) are shown to exhibit a pronounced dipolar-relaxation red shift of their principal fluorescence in protic solvents. For 1-HPQ, the
Autor:
José Luis G. De Paz, Jose Palomar, Juan Carlos del Valle, Javier Catalán, Michael Kasha, Cristina Díaz
Publikováno v:
Scopus-Elsevier
The solvatochromism of nine fluorophores which possess a five- or six-membered-ring intramolecular hydrogen bond is investigated. Upon variation of the polarity/polarizability, acidity and basicity of the solvent used, the observed fluorescence frequ
Publikováno v:
Chemical Physics Letters. 297:109-114
Quercetin (3,3′,4′,5,7-pentahydroxyflavone) in contrast to many hydroxyflavonols exhibits very little or no fluorescence in 298 K liquid solution or in the rigid glass protic solvents at 77 K. However, in the UV beam of the spectrofluorimeter a s