Energy migration in DNA evaluated by the sensitized fluorescence of an intercalation dye

An equation is obtained to calculated the efficiency of energy migration along a biopolymer with transfer of excitation to a fluorescence dye using excitation and absorption spectra. With the aid of bromoethydium intercalating into DNA-phage it is shown that in a solution at room temperature energy is transferred to it only from one or two neighboring nucleotides. The low efficiency of energy migration in relation to DNA under these conditions is explained by the low probability of each event of “cold” and “hot” migration. Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, 142292, Moscow Region, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 5, pp. 794–798, September–October, 1998.     

Ultrafast Photodynamics of the Indoline Dye D149 Adsorbed to Porous ZnO in Dye‐Sensitized Solar Cells

We investigate the ultrafast dynamics of the photoinduced electron transfer between surface‐adsorbed indoline D149 dye and porous ZnO as used in the working electrodes of dye‐sensitized solar cells. Transient absorption spectroscopy was conducted on the dye in solution, on solid state samples and for the latter in contact to a I^?/I₃^? redox electrolyte typical for dye‐sensitized solar cells to elucidate the effect of each component in the observed dynamics. D149 in a solution of 1:1 acetonitrile and tert‐butyl alcohol shows excited‐state lifetimes of 300±50 ps. This signature is severely quenched when D149 is adsorbed to ZnO, with the fastest component of the decay trace measured at 150±20 fs due to the charge‐transfer mechanism. Absorption bands of the oxidized dye molecule were investigated to determine regeneration times which are in excess of 1 ns. The addition of the redox electrolyte to the system results in faster regeneration times, of the order of 1 ns.     

A Theory of Luminescence of Light‐Collecting Molecular Systems

Expressions are obtained for the intensity and the quantum yield of the sensitized luminescence of the chromophore that plays the role of a reaction center in the simplest model trichromophore molecular [lightcollecting] antenna which is so constructed and so oriented in space that the irradiation photons coherently excite its other two chromophorespigments. The quantum electrodynamics formalism which takes into account the radiative dissipative interaction between the pigments and the reaction center of the antenna was used. The comparative analysis of the obtained expressions with the corresponding expressions for the luminescence of a bichromophore molecular system, differing from the trichromophore antenna by the absence of one of the pigments, has shown that the collective dissipative interaction of the pigments with the reaction center of the antenna can be considered as a highly efficient mechanism of [light collection] in molecular antennas.     

PHOTOOXYGENATION OF CAFFEINE SENSITIZED BY HYPOCRELLIN B

The photooxygenation of caffeine sensitized by Hypocrellin B in alcohol solvents hasbeen investigated in this paper. The products have been isolated and identified. The mainproduct is 8--alkoxyl substituted caffeine derivatives. Deuterium. oxygen partial pressure andNaN_3-quenching experiments indicate that the reaction proceeds on singlet oxygen mechanism.     

铽-妥舒沙星的敏化化学发光研究

镧系离子Tb3 能极大增强TSLX Ce(Ⅳ ) Na2 SO3 体系的化学发光强度 ,据此提出了妥舒沙星的敏化化学发光测定妥舒沙星 (TSLX)的新方法。在选定的最佳实验条件下 ,TSLX的浓度在 8.0× 1 0 -9～ 1 .0× 1 0 -5mol L-1 范围内与化学发光强度呈良好的线性关系 ,检出限为 5 .6× 1 0 -1 0 mol L ,对 1 .0× 1 0 -7mol L的TSLX标准溶液进行 1 1次平行测定 ,相对标准偏差为 1 .3 %。