Greetings! I am a post-grad student and have been working on producing metallic nanoparticles and oxides of them, via various wet chemical methods.
However, i have faced a small problem when carrying out spectroscopic analysis. Few of my specimens appear to exhibit rather large light absorbance peaks along with "noise", as seen on the next plot where a copper precursor was used. The dashed lines correspond to measurement of the same colloid on a prior date. I have read relative literature and couldn't come up with a definite answer. I have also carried out DLS measurements which have provided me with a report that the same colloid is polydispersed and includes particles at the nanoscale (
Dear Stavros A
The same problem I was facing during synthesis of copper nanoparticles. I was worried from the noisy peaks...finally i got clear peak by decreasing the concentration of stabilizing agent and taking very dilution solution for UV analysis....minimum 3 to 4 drop and maximum 0.5 mL in distilled water filled 3 mL Uv cuvette.
Try these..hope you got results.
Merry Christmas
Dear Stavros A
The same problem I was facing during synthesis of copper nanoparticles. I was worried from the noisy peaks...finally i got clear peak by decreasing the concentration of stabilizing agent and taking very dilution solution for UV analysis....minimum 3 to 4 drop and maximum 0.5 mL in distilled water filled 3 mL Uv cuvette.
Try these..hope you got results.
Merry Christmas
The refractive index is not required for the intensity distribution in DLS. This question has been asked and answered many times on ResearchGate. See also, for example: http://www.materials-talks.com/blog/2014/01/23/intensity-volume-number-which-size-is-correct/
If one is wanting to convert from intensity to volume then the optical properties are required. This is the wavelength of the utilized laser (typically He-Ne at 632.8 nm) and literature values are easily obtained. A robustness check will almost certainly confirm that they exert little effect on the generated distribution for particles in the Rayleigh size region.
The most robust values coming from DLS are the z-average and polydispersity index (PDI) arising from the cumulants analysis. See the international standards ISO13321:1996. ISO22412:2008, and ASTM E2490-09 (15).
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