Related Experiment Video
Updated: Mar 18, 2026

Diffuse Reflectance Infrared Spectroscopic Identification of Dispersant/Particle Bonding Mechanisms in Functional Inks
Published on: May 8, 2015
Characterization of Aqueous Oleic Acid/Oleate Dispersions by Fluorescent Probes and Raman Spectroscopy
Keishi Suga1, Dai Kondo1, Yoko Otsuka1
1Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan.
Abstract:
Oleic acid (OA) and oleates form self-assembled structures dispersible in aqueous media. Herein, the physicochemical properties of OA/oleate assemblies were characterized using fluorescent probes and Raman spectroscopy, under relatively high dilution (<100 mM of total amphiphile) at 25 °C. Anisotropy analysis using 1,6-diphenyl-1,3,5-hexatriene showed that the microviscosity of the OA/oleate assembly was highest at pH 7.5 (the pH range of 6.9-10.6 was investigated). The fluorescence spectra of 6-lauroyl-2-dimethylaminonaphthalene revealed the dehydrated environments on membrane surfaces at pH < 7.7. The pH-dependent Raman peak intensity ratios, chain torsion (S = I1124/I1096) and chain packing (R = I2850/I2930), showed local maxima, indicating the occurrence of metastable phases, such as dispersed cubic phase (pH = 7.5), vesicle (pH = 8.5), and dispersed cylindrical micelle (pH = 9.7). These results suggest that large-scale OA/oleate assemblies could possess particular membrane properties in a narrow pH region, e.g., at pH 7.5, and 9.7.
Related Concept Videos
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency,...
Raman Spectroscopy: Overview
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
Spectroscopy of Carboxylic Acid Derivatives
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in...
Raman Spectroscopy Instrumentation: Overview
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...

