How can I calculate the average size for Au NPs fro UV/Vis spectroscopy only, without TEM?
Dear Mohammad,
The attached publication describes a method to calculate the average size for Au NPs from UV/Vis spectroscopy only, without TEM.
Size Evaluation of Gold Nanoparticles by UV#vis Spectroscopy
Vincenzo Amendola, and Moreno Meneghetti
J. Phys. Chem. C, 2009, 113 (11), 4277-4285• DOI: 10.1021/jp8082425 • Publication Date (Web): 24 February 2009
Size Evaluation of Gold Nanoparticles by UV-vis Spectroscopy
Vincenzo Amendola and Moreno Meneghetti*
Department of Chemical Sciences, UniVersity of PadoVa, Via Marzolo 1, I-35131 PadoVa, Italy
ReceiVed: September 16, 2008; ReVised Manuscript ReceiVed: January 7, 2009
We present a method for the evaluation of the average size of gold nanoparticles based on the fitting of their UV-vis spectra by the Mie model for spheres. The method gives good results using a calibration of the dumping frequency of the surface plasmon resonance and accounting for the presence of nonspherical AuNP
in solution by the Gans model for spheroids. It has been successfully applied to free and functionalized gold nanoparticles in various solvents with diameters in the 4-25 nm range. Despite the differences among samples, we found an accuracy of about 6% on the nanoparticles average size with respect to sizes measured by
transmission electron microscopy (TEM). Moreover, the fitting model provides other information not available from TEM like the concentration of AuNP in the sample and the fraction of nonspherical nanoparticles, which is particularly useful for measuring aggregation processes. The fitting procedure and models are
thoroughly discussed in the text, and the fitting programs are freely accessible on the web.
Conclusions:
Size, concentration, and aggregation level of gold nanoparticles are key points for their applications. We presented in detail a method for estimating these properties by UV-vis spectroscopy, based on the fitting of experimental spectra with the Mie
and Gans models. Calibration of the SPR dumping frequency Γ allowed an accuracy on the evaluation of average particles size of about 6% for different types of AuNP solutions with diameters between 4 and 25 nm. A model for the estimation of the size distribution of AuNP by extending the fitting of the UV-vis spectra down to 200 nm range was also shown to give good results. Through the calibration procedure and the fitting program, which is provided on the web (see Supporting Information), the MG fitting can be adjusted to the case of other nanoparticles
with a characteristic SPR in the UV-vis like silver, copper, and noble metals alloys.
Hoping this will be helpful,
Rafik
Dear Mohammad,
The attached publication describes a method to calculate the average size for Au NPs from UV/Vis spectroscopy only, without TEM.
Size Evaluation of Gold Nanoparticles by UV#vis Spectroscopy
Vincenzo Amendola, and Moreno Meneghetti
J. Phys. Chem. C, 2009, 113 (11), 4277-4285• DOI: 10.1021/jp8082425 • Publication Date (Web): 24 February 2009
Size Evaluation of Gold Nanoparticles by UV-vis Spectroscopy
Vincenzo Amendola and Moreno Meneghetti*
Department of Chemical Sciences, UniVersity of PadoVa, Via Marzolo 1, I-35131 PadoVa, Italy
ReceiVed: September 16, 2008; ReVised Manuscript ReceiVed: January 7, 2009
We present a method for the evaluation of the average size of gold nanoparticles based on the fitting of their UV-vis spectra by the Mie model for spheres. The method gives good results using a calibration of the dumping frequency of the surface plasmon resonance and accounting for the presence of nonspherical AuNP
in solution by the Gans model for spheroids. It has been successfully applied to free and functionalized gold nanoparticles in various solvents with diameters in the 4-25 nm range. Despite the differences among samples, we found an accuracy of about 6% on the nanoparticles average size with respect to sizes measured by
transmission electron microscopy (TEM). Moreover, the fitting model provides other information not available from TEM like the concentration of AuNP in the sample and the fraction of nonspherical nanoparticles, which is particularly useful for measuring aggregation processes. The fitting procedure and models are
thoroughly discussed in the text, and the fitting programs are freely accessible on the web.
Conclusions:
Size, concentration, and aggregation level of gold nanoparticles are key points for their applications. We presented in detail a method for estimating these properties by UV-vis spectroscopy, based on the fitting of experimental spectra with the Mie
and Gans models. Calibration of the SPR dumping frequency Γ allowed an accuracy on the evaluation of average particles size of about 6% for different types of AuNP solutions with diameters between 4 and 25 nm. A model for the estimation of the size distribution of AuNP by extending the fitting of the UV-vis spectra down to 200 nm range was also shown to give good results. Through the calibration procedure and the fitting program, which is provided on the web (see Supporting Information), the MG fitting can be adjusted to the case of other nanoparticles
with a characteristic SPR in the UV-vis like silver, copper, and noble metals alloys.
Hoping this will be helpful,
Rafik
You can calculate the size from XRD. very good explanation is here on this link,
http://www.instanano.com/characterization/theoretical/xrd-size-calculation/
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