Photoluminescence excitation

Photoluminescence excitation (PLE) is a technique used to investigate the electronic properties of materials, particularly semiconductors and quantum dots. In this method, a sample is illuminated with varying wavelengths of light (typically in the ultraviolet or visible range) to excite electrons from the valence band to the conduction band. As the sample absorbs photons, it can re-emit them at longer wavelengths, which is known as photoluminescence.