Characterization of the fluorescence correlation spectroscopy (FCS) standard Rhodamine 6G and calibration of its diffusion coefficient in aqueous solutions
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany)
Precise diffusion measurements of rhodamine 6G (Rh6G) dissolved in D{sub 2}O at concentrations between 50 and 200 μM were carried out in the temperature range from 280 to 320 K using pulsed field gradient nuclear magnetic resonance (PFG-NMR). The obtained diffusion coefficients can be used as a calibration reference in fluorescence correlation spectroscopy (FCS). Besides measuring the diffusivity of Rh6G, the diffusion coefficient of the solvent in the same system could be determined in parallel by PFG-NMR as the resonances of water and Rh6G are well separated in the {sup 1}H NMR spectrum. To analyze the differences due to the isotope effect of the solvent (D{sub 2}O vs. H{sub 2}O), the correlation time τ{sub D} of Rh6G was measured by FCS in both D{sub 2}O and H{sub 2}O. The obtained isotopic correction factor, τ{sub D}(D{sub 2}O)/τ{sub D}(H{sub 2}O) = 1.24, reflects the isotope effect of the solvent´s self-diffusion coefficients as determined previously by PFG-NMR.
- OSTI ID:
- 22255009
- Journal Information:
- Journal of Chemical Physics, Vol. 140, Issue 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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