Role of high pressure for understanding luminescent phenomena

High-pressure techniques make possible to investigate the changes in the electronic properties induced by modifications of the local or crystal structure of the material without changing the chemical composition. The different sensitivity of excited states to crystal-field strength enables energy tuning of the states, which are eventually responsible for the optical properties. It is possible to induce resonance between levels producing exotic effects like upconversion as well as excited state crossover or high-spin to low-spin transitions. Herein, we present selected examples of high-pressure effect for understanding luminescent phenomena or even inducing new ones.