We are working on the preparation of transition metal dichalcagonide (TMD) samples with 60-90µm sized monolayer trinangles of WS2, MoS2, WSe2 or MoSe2. The goal is to cover a large area of the substrate with monolayer TMDs to perform further experiments. We are looking for a cheap and straight-forward method to get a first quick estimate of the sample quality right after production in our CVD set-up. I know that the PL quantum yield is much higher for monolayer TMDs than for multilayers. Therefore, I have the idea to put them onto an optical microscope with up to 1000x magnification and look at the luminescence. My first approach was to do the optical excitation with a laser (laser pointer, laser diode, HeNe). However, I realized that a lot microscope nowadays offer the option of LED irradiation. Is green LED irradiation sufficient to measure PL of TMDs?