Photoluminescence of doped ZnO NRs sample was measured using Fluoromax-4 Spectrofluorimeter (HORIBA Jobin Yvon, model FM-100) of UV-Vis range. I have exited at 360 nm and given input emission range as 375-750 nm. Then I got a peak broad peak with lambda max at 625 nm and got an overtone peak (not of doped ZnO sample) starting from 710 nm and not able to get complete proper emission peak range beyond 710 nm to 800 nm. I have attached the photoluminescence peak datafile below.

emission peak range = (360 nm X 2) -10 = 710

Beyond this 710 nm, I could not get complete.

Can you explain the reason for this incomplete peak beyond 710 nm