照相光谱增感染料在溴化银沉淀表面的吸附及吸附热测量

用离心分离法得到25℃菁染料Ⅱ和Ⅲ分别在几种溶剂的溴化银分散系中的吸附等温线;记录了染料溶液的吸收光谱和吸附态染料的反射光谱。采用精密量热技术得到25±0.01℃溴化银从DMF-水溶液中吸附染料Ⅱ等位摩尔吸附热为-(3.18±0.09)KJ/mol(θ=0.87)。还对从DMF溶液中吸附染料Ⅱ的体系绘制了以单位溴化银表面的吸附热表示的吸附等温线,表明用精密量热技术可以研究染料的吸附过程。

Adsorption of Photographic Spectral Sensitizing Dyes to Silver Bromide and Enthalpy of Adsorption Measurements

The adsorption isotherms of c'yanine dyes Ⅱ and Ⅲ (1-methyl-1'-(γ-sulfopropyl)-2,2'-cyanine Ⅱ and its 6'-methyl analog Ⅲ) on AgBr suspensions in several solvents were obtained at 25℃ by centrifugation method. Corresponding absorption (reflection) spectra of these dyes in solutions and in adsorbed states over a wide concentration range were recorded. The solvent effect on dye adsorption and on the aggregation states of dye molecules were discussed. The very small heat effect in dye adsorption was measured at 25±0.01℃ with the Versatile Precision Semiconductor Calori-metric System developed in this lab using a specially designed calorime-tric unit. The precision environmental temperature control to 25±0.0001℃ is implemented by a microcomputer system. The isosteric molar heat of adsorption of dye Ⅱ in DMF-Water (1:1) to AgBr was obtained at 25℃ to be (3.18 ±0.09) kJ/mol (θ=0.87). Also calorimetric measurements were made for adsorption of dye Ⅱ in DMFto AgBr over a wide concentration range, and the isotherm expressed in terms of enthalpy per m² AgBr surface was drawn with the shape essentially in parallel with that obtained from the phase separation method. This result shows that the precision calorimetry can be used for the study of dye adsorption process.