光谱增感染料798的聚集效应与AgBr上的吸附

The Aggregation Behavior of Photographic Scnsitizing Dye (3,3-dihydroxycthyl-5,5-dimethoxy-9-cthyl Thiacarbocyanine Chloride)in Solution and in Its Adsorbed State on the Surface of Silver Bromide

对用于黑白片感红染料798(3,3′—二羟乙基—5,5′—二甲氧基—9—乙基—噻碳菁氯盐)由记录其吸收光谱,反射光谱,研究了它在甲醇,水及KBr水溶液中的聚集效应和吸附于AgBr表面的吸附态性质.得到在甲醇中以单分子态存在的最大吸收入max为560nm.25℃水溶液中(5×10^(-6)～2.5×10^(-5)5mol/L)存在二聚平衡(λ_D=520nm),二聚平衡常数K(298K)=1.28×10^(-5)(△γG(298K)=27.9kJ)以及△γH(298K)=35.2KJ,△γ(298K)=24.5JK^(-1).25℃的吸附等温线表明798在AgBr上为多层吸附,第一吸附层的饱和吸附量是0.73μmol/g,[按单分子染料单元计算)吸附态的表面反射光谱表明,只在第一层中存在J-聚集状态.

The aggregation behavior of (3.3'-dihydroxy ethyl-5.5'-dimethoxy -9-ethylthiac-arbocyanine Chloride)in CH,OH,H_2Oand in the adsorbed state on AgBr surface was studied from the absorption and reflection spectra,and from adsorption isotherms at 25℃. NO J-absorption, but only dimer-monomer equilibra were observed form the solution spectra of the experimental of concentration range, the dimerzation constant△_rH (298K) and △_rS(298K)were found spectrophotometrically to be K(298K)=1.28×10^(-5) △G° = 27.9kJ ,35.2kJ and 24.5JK^(-1), respectively. The adsorption isotherm abtained at 25℃ was multilayer-type with saturated monolayer capacity 0.73umol/ g(AgBr) (expressed as monomer units of the dye) .The surface reflection spectra showed that after the J-band had reached critical intensity( λ_(Ja) = 640nm),the further additions of dye only caussed H-aggregate and monomer formations.this indicated that only dye molecules in the first adsorbed layer existed as J-aggregats,the adsorption states in subsequent dye layers are different.