I have done the procedure many time for ZnO NPs synthesized via Green synthesis method from leaf extract but I didn't get the desire peak for UV absorption mentioned in literature that is from 330nm to 390nm , every time I just got the peak 208nm to 220nm following the concentrations ( 1: 1 means 1mg ZnO NPs & 1ml dH2O) and ( 1:5 means 1mg NPs & 5ml dH2O ) respectively.
The first step color change is done nicely during synthesis of NPs.
So please help what I do to get the peak mentioned in literature for ZnO NPs.
Thanks!