Monomolecular dye layers

K.H. Drexhage (1974) Interaction of light with monomolecular dye layers. In Progress in Optics. Vol. 12 (Ed E. Wolf). Interscience, Amsterdam, 163-232. 

Fig. 10.14 Photocurrent action spectra for monomolecular layers of cyanine dyes at a Sn02/In203 electrode at pH 10 with 0.5 M allylthiourea. Molar ratio of dye to arachidic acid, 1 5. The parameters for different curves are explained by the structure of dye layers shown at the top of the figure. (After ref. [34])...

A. Ruaudel-Teixier and M. Vandevyver, Energy transfer in dye monomolecular layers, Thin Solid Films 68, 129-133 (1980). 

Absorption measurements, however, on such fatty acid layers mixed with dye molecules which are deposited on glass slides can be used for estimating light absorption in the layer of dye molecules at the crystal surface. A monomolecular layer of dye molecules with an absorption coefficient of 105 M-1 cm-1 as for... 

Electronic excitation of one chromophore sometimes elicits fluorescence from a different chromophore that is located nearby. For example, excitation of a monomolecular layer of dye can induce fluorescence in a layer of another dye spaced 5 nm... 

France suggested that the retardation of growth perpendicular to a face might occur even if the amount of adsorbed impurity was insufficient to form a complete monomolecular layer, and Buckley has expressed the same view. Dyes are often included in crystals, presumably when the retardation of growth by adsorbed dyes is insufficient to stop growth completely. 

Our attention has been directed to modifying Sn02 electrodes and later, metal electrodes with very thin films (10-100 molecular layers) of phthalocyanines which appear to aggregate when sublimed. The oriented phthalocyanine phase or phases sensitize the response of the Sn02 electrodes with efficiencies many times greater than monomolecular layers of covalently attached chromophores or randomly oriented multilayer dye films (9). Our initial studies have been conducted with phthalocya-nines which we expected would orient in a linear "pancake-stack," by virtue of the interaction between the central metal atoms — either a covalent bond or a strong electrostatic interaction. 

Determination of the absolute fluorescence quantum yields for solids is usually much more difficult than for solution systems. A method based on energy transfer has been employed to determine the absolute Of of thiocyanine dye molecules in monomolecular layers.113... 

Recently, the Langmuir-Blodgett (LB) technique has been recognized as a useful way of tailoring thin films of molecular thickness. Interest in the LB technique has led to a number of investigations of different types of materials. For example, the classic long-chain fatty acids and alcohols as well as polymerizable molecules, e.g. diacetylenic acids [211-213], aromatic hydrocarbons, e.g. substituted anthracenes [214, 215], TCNQ radical anion salts [216, 217] and charge transfer complexes [218-220] and dye substances can now all be produced as monomolecular layers. 

If a molecular species completely saturates the adsorberrt surface with a single layer of molecules (or ions), the adsorption is known as urtimolectrlar or monomolecular. On the other hand, the formation of mrrlti-layers can occur, referred to as multimolecirlar adsorptiorr. The latter, no dorrbt, occrrrs in the dyeing of nylon fibres with mono-sulphonated acid (fyes, where dye aggregation is believed to take place within the fibre. 

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