This is the case of a wide bandgap, natural silicate material (~7.7 eV). The excitation spectrum is recorded for a defect (depth from the conduction band edge is ~ 2.1 eV). Any leads will be highly appreciated.
In principle, you need PL excitation as a complementary technique for PL mainly to identify the origin of multiple peaks feature . In my opinion this is only absorption growth apparently belonging to intrinsic absorption threshold of silica glass.
Hi Raju Kumar,
how exactly does the energy diagram look like, or what would you expect it to look like? Right now, the excitation PL you are showing combined with the description you gave is a bit confusing. Usually, for an excitation PL spectrum, you would let your detector sit on one given emission wavelength (e.g. emission maximum) and let the light source scan through the different excitation wavelengths. However, your material seems to have a bandgap of 7.7 eV, and the defect is located 2.1 eV "below" your conduction band edge; this means the defect is about 5.6 eV "above" the valence band edge? If this is the case, then how do you come to the conclusion that the peak at 1.5 eV is the first excited state, if the energy differences I listed above are all larger than 1.5 eV?
In any case, I would like to know what emission wavelength was kept constant?
Hi Joachim Vollbrecht
Thank you for your comment. The emission energy is fixed at 1.30 eV (wavelength ~955nm). The first resonance (~1.45 eV) has been identified as the first excited state using other methods (for e.g. optically stimulated luminescence (OSL), radio-luminescence), and the trap depth (defect location in energy below CB edge) has been obtained around 2.1 eV using OSL. Since with PL we are looking at the same trap, resonances in PL excitation spectrum should make same sense.
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