Hi All,
I have attempted to synthesis ZnO nano for the first time according to the paper attached (zinc acetate dissolved in ethanol combined with NaOH in ethanol and stirred for 12 hours). I have not been able to find any supporting information or reference to the method they describe in the paper.
It is my understanding that depending on the method of synthesis the characteristic peaks for the ZnO will vary. Attached a copy of my spectrum (apologies for the excel sheet!) and i can see two very weak peaks that correspond close to other literature values of ZnO nano but the peaks to the left are confusing me. If someone would be able to explain what the peaks to the left could be or why my absorbance for the two peaks around 280nm and 380nm are so weak? (an arbitrary amount of sample was used for the analysis and this weak signal could just be v low concentration).
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cheers.
I think absorption peak near 370-380 nm is due to strong absorption and peak at near 280 nm is due to excitonic absorption in ZnO nanoparticles. Meaning your ZnO nanoparticles have band gap near 370-380 nm (most absorption occuring), whereas some electrons are also being excited to higher energy levels (near 280 nm).
M. A. Uddin you are correct. I replotted my data and the spectra looks compatible with ZnO nano. The noise to the left I am going to say was from the quartz cuvette.
Indeed, you have a quite low concentration. I guess also a very small amount of ZnO. I suggest to perform at least a TEM analysis (+XPS) and even better XRD and UV-vis with a higher concentration and/or a thicker cuvette. Here, you cannot exclude the effect of the "Equipment" (light intensity, possible baseline issues, D2 to W lamp change).
You might take a look in some of our publications resulting in higher concentrations of well-defined and analyzed ZnO nanoparticles.
Article Synthesis and testing of ZnO nanoparticles for photo-initiat...
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