In the fig. given is a PL Emission spectra of ZnO.

(1.) How to understand or to determine the no. of maximum or min. peaks to which the given spectra can be deconvoluted? Or else, are all these things are done by trial and error method?

(2) How can one determine which function—such as Gaussian, Lorentzian, or Voigt—is most appropriate for deconvolution?

(3.) Why does the fitting process sometimes fail to converge, displaying a message indicating overparameterization? What does it mean? How to rectify it?

(4)If there is any textbooks, tutorials, you tube videos, or any learning platform about peak fitting please mention.

I shall be thankful to valuable suggestions.