Rotational reorientation dynamics of Aerosol-OT reverse micelles formed in near-critical propane

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Applied Spectroscopy

DOI:https://doi.org/10.1366/0003702963905691· OSTI ID:633973

Heitz, M P; Bright, F V ^[1]

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1. Department of Chemistry, Natural Sciences and Mathematics Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000 (United States of America)

The rotational reorientation kinetics of two fluorescent solutes (rhodamine 6G, R6G, and rhodamine 101, R101) have been determined in sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol-OT, AOT) reverse micelles formed in liquid and near-critical propane. We show that the amount of water loading ([water]/[AOT], R), continuous phase density, and temperature all influence the solute rotational dynamics. In all cases, the decay of anisotropy data (i.e., frequency-dependent differential polarized phase angle and polarized modulation ratio) are well described by a bi-exponential decay law. We find that the faster rotational correlation times are similar to but slightly less than the values predicted for an individual AOT reverse micelle rotating in propane. The recovered rotational correlation times range from 200 to 500 ps depending on experimental conditions. This faster rotational process is explained in terms of lateral diffusion of the fluorophore along the water/headgroup interfacial region within the reverse micelle. The recovered values for the slower rotational correlation times range from 7 to 18 ns. These larger rotational reorientation times are assigned to varying micelle-micelle (i.e., tail-tail) interactions in the low-density, highly compressible fluid region. We also quantify the contribution of the reverse micellar {open_quotes}aggregate{close_quotes} to the total decay of anisotropy. {copyright} {ital 1996} {ital Society for Applied Spectroscopy}

• DOE Contract Number: FG02-90ER14143
• OSTI ID: 633973
• Journal Information: Applied Spectroscopy, Journal Name: Applied Spectroscopy Journal Issue: 6 Vol. 50; ISSN 0003-7028; ISSN APSPA4
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
DENSITY
FLUORESCENCE
MICELLAR SYSTEMS
PROPANE
RHODAMINES
ROTATIONAL STATES
TEMPERATURE DEPENDENCE
WATER INFLUX