Photoluminescence Spectroscopy

PL spectroscopy studies material properties by analyzing the light a sample re-emits after absorbing photons — a standard tool in materials science, semiconductor research, and nanotechnology.

The process, in four steps

• Excitation: laser light lifts electrons in the material into an excited state.
• Relaxation: the electrons gradually return to the ground state, releasing excess energy as heat and light.
• Emission: the emitted light has a longer wavelength than the light that excited it — it carries less energy.
• Spectral analysis: the wavelengths of the emitted light reveal band gaps, defects, and interactions within the material.

In practice, the emitted light's intensity is typically plotted against wavelength — this spectrum reveals the quality and electronic structure of the sample under study.