I synthesized the gold nanoparticle in pH11 medium and left it for days in room temperature without light. But then I observe that during day 3 the peak are higher than day 2 n 1 whereas day 1 are lower than 2 and 3. Is that possible to happen?
Ainin Razak
Without further details it's easy to speculate - aggregation and settling are my favored reasons... Carry out a Stokes' Law calculation to see what size particles could remain in suspension. Gold has a high density of 19.3 g/cm3.
You may possibly also observe a change in color of the samples. Here is an application note relating the size (from DLS) with a photograph of colloidal gold samples: https://instrumat.ch/wp-content/uploads/2016/08/MRK956-01-Characterisation-of-colloidal-Gold-using-DLS-LRLL.pdf
Dear Ainin Razak , Metallic nanoparticles are not stable, unless you use some stabilizing agent. Normally the particle size increases with time. The change in absorbance value is related with particle size of nanomaterials. You will need to do some additional analysis in order to correlate your observation. You can do DLS and SEM to see what is the effect of time on particle size and morphology. That will explain your change is absorbance value. Another possibility is instrument related error. The absorbance value may change if you analyze the same sample also at different times.
Alan F Rawle Thank you the answer, will figure out about Stoke's law more.
Ulf Nobbmann Thank you for the attachment, appreciate a lot.
Ranjit Kumar Thank you for your suggestion,appreciate a lot.
-Increasing the intensity may be represent the increasing the concentration of the formed nanoparticles (the number of Au NPs) this may be assigned to that reaction still working.
- On other hand using weak stabilizing agent, give the chance of aggregation specially if you prepare nanoparticles in the presence of polysaccharides.
if you dont mind can you share the literature regarding your first answer Ayman S ELmezayyen
Ainin Razak
plz, check the attached images 1,2 snapped from the article:
Article Zinc selenide nanoparticles (ZnSe−NPs): Green synthesis and ...
I hope it help
Good luck
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