Whatever emission maxima (Lambda Emission) we got for the analyte, we got second harmonic at double value of emission maxima...you rescale your graph to remove it...because it's intensity usually vary, but intensty of emission peak is relatively recurring....
Second harmonic is optical phenomenon that was largely related to your equipment. It can be reduced, minimized or completely eliminated sometimes, subject to how your PL was measured.
Jp Wu how will i know that this peak is due to second harmonic ??? in can be an internal property of PL ..! Mohsen Kia Kundan Tayade Haleemah J. Mohammed
There is an Eq. that you should be able to calculate or estimate its position according to the 1st order peak of PL Em. 2ndly, it is a so nice peak in practice regarding its peak shape, etc. against the 1st. 3rdly, you could vary Ex wavelength to see its position changes with the 1st order PL Em peak. depending on your equip. Interestingly, it can be 2/3, etc. instead of 2nd harmonic peak, although the last largely dorminated harmonic signals in PL Em.
I did 2D and 3D plot of PL Em versus PL Ex to remove or minimize its impact in my PhD study a long time ago.