Nanosecond reorganization of water within the interior of reversed micelles revealed by frequency-domain fluorescence spectroscopy

Journal Article · Thu Oct 03 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100173a064· OSTI ID:7265876

Zhang, Jing; Bright, F V ^[1]

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1. State Univ. of New York, Buffalo (United States)

The fluorescence properties of 1,8-ANS (1-anilino-9-naphthalenesulfonic acid) in AOT (Aerosol-OT; 1,4-bis(2-ethylhexyl) sulfosuccinate) reverse micelles have been studied. Steady-state and time-resolved methods show that water content and temperature play key roles in the photophysics of the emission process. For example, a continuous red shift of the emission spectrum is observed as the water content within the AOT reverse micelle increases. New multifrequency phase and modulation experiments show clearly that the 1,8-ANS emission spectrum is continuously evolving on a nanosecond time scale. From these experiments, the authors find that the solvation correlation functions (S(t)) are characterized by a pair of solvent relaxation rates when the water content is at or below R {approx} 2.5 (R, molar ratio of water to AOT). Above R {approx} 2.5 (r{sub w} {approx} 2R {approx} 5{angstrom}, r{sub w} is the core radius of the water droplet) the authors observe a single relaxation process. It is proposed that, as lower water levels, the two solvation rates are a consequence (in part) of interfacial (type 1) and core (type 2) associated water, each characterized by its own relaxation rate. Upon increasing the water content within the reverse micelle, the relative fraction of type 2 water increases and the solvent relaxation process collapses into a single relaxation rate. From temperature-dependent studies they determine the activation barriers for each of these solvent reorganization events.

• DOE Contract Number: FG02-90ER14143
• OSTI ID: 7265876
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:20; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
CARBOXYLIC ACIDS
DATA
DICARBOXYLIC ACIDS
EMISSION SPECTROSCOPY
ENERGY
ESTERS
EXPERIMENTAL DATA
FLUORESCENCE SPECTROSCOPY
HYDROGEN COMPOUNDS
INFORMATION
MICELLAR SYSTEMS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
RESOLUTION
SOLVATION
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SUCCINIC ACID
SULFONIC ACID ESTERS
SULFONIC ACIDS
SURFACTANTS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TIME RESOLUTION
TIMING PROPERTIES
WATER