Sm. Ohline et al., Quantification of methylene blue aggregation on a fused silica surface andresolution of individual absorbance spectra, CHEM P LETT, 346(1-2), 2001, pp. 9-15
The absorbance spectra of individual methylene blue aggregates adsorbed by
spin coating on a fused silica surface are resolved. Using singular value d
ecomposition and a model incorporating Beer's Law and elemental conservatio
n, a varied concentration family of UV-Vis spectra are fit. Results indicat
e that H-dimer formation occurs beginning at a surface concentration of 3 x
10(13) molecules/cm(2), and further aggregate formation, including J-type
dimers, is significant above 2 x 10(14) molecules/cm(2). Based on our resul
ts, past assumptions that a spin-coated surface (using a millimolar coating
solution) results in a monolayer of methylene blue monomers should be reex
amined. (C) 2001 Elsevier Science B.V. All rights reserved.