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Microdialysis of Ethanol During Operant Ethanol Self-administration and Ethanol Determination by Gas Chromatography
Published on: September 5, 2012
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Rhodamine 6G Structural Changes in Water/Ethanol Mixed Solvent.
Mingyu Chapman1, William B Euler2
1Department of Chemistry, University of Rhode Island, 140 Flagg Road, Kingston, RI, 02881, USA.
Journal of Fluorescence
|October 22, 2018
Summary
Rhodamine 6G forms aggregates in water, but this can be controlled by mixing with ethanol. Researchers measured monomer and dimer sizes, finding aggregation occurs in the ground state.
Area of Science:
- Photochemistry
- Materials Science
- Spectroscopy
Background:
- Rhodamine 6G (Rh6G) is a fluorescent dye known to aggregate in solution.
- Solvent polarity significantly influences the aggregation behavior of dyes.
- Understanding dye aggregation is crucial for applications in sensing and optoelectronics.
Purpose of the Study:
- To investigate the aggregation of Rhodamine 6G in mixed water-ethanol solvents.
- To characterize the spectral properties of Rh6G monomers and aggregates.
- To determine the size of Rh6G aggregates using light scattering.
Main Methods:
- UV-Vis absorption and fluorescence emission spectroscopy.
- Dynamic Light Scattering (DLS) for particle size analysis.
- Varying the water-ethanol ratio to control dye aggregation.
Main Results:
- Rh6G aggregation is concentration-dependent and solvent-composition-dependent.
- Absorption spectra reveal monomer (S1 π-π* transition and vibronic side band) and H-dimer formation.
- Emission spectra show monomer, dimer, and excimer aggregate emission.
- Monomer and dimer average diameters were measured as 1.4 ± 0.2 nm and 3.3 ± 0.6 nm, respectively.
- Aggregation occurs in the ground state.
Conclusions:
- The water-ethanol ratio precisely controls Rh6G aggregation, even at high concentrations.
- Ground-state aggregation influences the observed excited-state properties.
- This study provides fundamental insights into dye aggregation mechanisms in mixed solvents.
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