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'fluorescence' in keywords Facet   Publication Year 1980  [X]
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1Author    P. V. Sane, T. S. Desai, V. G. TatakeRequires cookie*
 Title    Luminescence from Photosystem I at High Temperatures  
 Abstract    The changes in the fluorescence and delayed fluorescence intensity of spinach leaf as affected by temperature were studied. It was observed that the delayed fluorescence showed a maximum at about 45 °C whereas the fluorescence maximum was at about 55 °C. An examination of the emission spectra of delayed fluorescence at different temperatures showed that at higher tem­ peratures the relative emission at 735 nm was increased. It is argued that at higher temperatures the luminescence from photosystem I contributes to delayed fluorescence. 
  Reference    Z. Naturforsch. 35c, 289—292 (1980); received November 1 1979 
  Published    1980 
  Keywords    Fluorescence, Delayed Fluorescence, Photosystem I 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0289.pdf 
 Identifier    ZNC-1980-35c-0289 
 Volume    35 
2Author    GeoffreyA. Codd, G. Eorg, H. SchmidRequires cookie*
 Title    Effects of S-^^-DichlorophenyO-N-N'-Dimethylurea on Oxygen Evolution and Fluorescence by Whole Filaments and Isolated Thylakoids of the Cyanobacterium Anabaena cylindrica  
 Abstract    The site of inhibition of DCM U against photosystem II in the cyanobacterium (Blue-green alga) Anabaena cylindrica was examined in electron transport and fluorescence studies. Isolated thylakoids catalyzed silicomolybdate photoreduction using H zO as electron donor; the steady-state reaction was completely inhibited by DCM U. This reaction is insensitive to DCM U in chloro­ plasts, since silicomolybdate accepts electrons from the prim ary photosystem II acceptor, and thus before the site of action o f D CM U in higher plants. DCM U did not increase the steady-state level of fluorescence by inact A. cylindrica, nor affect the monophasic fluorescence induction, with 
  Reference    Z. Naturforsch. 35c, 649—655 (1980); received April 18 1980 
  Published    1980 
  Keywords    Oxygen-Evolving Side, Cyanobacteria, D CM U-Sensitivity, Fluorescence 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0649.pdf 
 Identifier    ZNC-1980-35c-0649 
 Volume    35 
3Author    Jacek Wierzchowski, M. Arian Szczęśniak, D. Avid ShugarRequires cookie*
 Title    Fluorescence Emission Properties of the Cation of 4-Aminopyrazole(3,4-d) pyrimidine, an Adenine Analogue: Evidence for Phototautomerism  
 Abstract    A study has been made of the emission spectra at room temperature, in aqueous and alcoholic media, of 4-aminopyrazolo(3,4-d)pyrimidine (APP) and some o f its methylated derivatives. The cationic forms APPH+, N 2-methyl-APPH+ and N 7-methyl-APPH+ exhibit intense fluorescence un­ der these conditions, the first two exhibiting excitation spectra which differ from the absorption spectra, pointing to the existence o f a tautomeric equilibrium in the ground state. From the shape o f the excitation spectra, and comparisons with methylated analogues in fixed tautomeric forms, it follows that the emission of APPH+ originates exclusively from the species N (2)-H ,N (7)-H +, the other forms being non-fluorescent. The proportion o f the emitting species, calculated from the ex­ citation wavelength dependence o f the quantum yield, is in good agreement with data for the ground state. The emission spectrum of APPH+ in aqueous medium consists o f two bands with /lmax 360 nm and 430 nm, which exhibit identical excitation spectra, but are quenched to different extents by H30 +. The 430 nm emission band is absent in alcoholic media. A similar behaviour is exhibited by N 7-methyl-APPH+, whereas the neutral form o f this analogue exhibits only the 430 nm band. These results indicate that the long wavelength emission band o f APPH+ originates from the rare tautomeric species N(7)-H formed in the excited state by photodissociation o f the N(2)-H proton from the species N(2)-H ,N(7)-H+. This is further confirmed by results obtained with the aid o f the basicity method, as well as by salt efects in non-aqueous media. Consideration is given to the possibility of such processes occurring in other analogues o f nucleic acid derivatives. 
  Reference    Z. Naturforsch. 35c, 878—8 (1980); received July 28 1980 
  Published    1980 
  Keywords    Fluorescence, Phototautomerism, Pyrazolo(3, 4-d)pyrimidines, Adenine Analogues, Protonation Sites 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0878.pdf 
 Identifier    ZNC-1980-35c-0878 
 Volume    35