Free electron gas; Free electrons; Free electron (disambiguation)
Free-electron laser
TYPE OF LASER
XFEL; X-ray free-electron laser; Free electron laser
A free-electron laser (FEL) is a (fourth generation) light source producing extremely brilliant and short pulses of radiation. An FEL functions and behaves in many ways like a laser, but instead of using stimulated emission from atomic or molecular excitations, it employs relativistic electrons as a gain medium.
A SIMPLE MODEL FOR THE BEHAVIOUR OF VALENCE ELECTRONS IN A CRYSTAL STRUCTURE OF A METALLIC SOLID
Free-Electron Model of Metals; Free-electron theory of metals; Drude-Sommerfeld model; Drude–Sommerfeld model; Free-electron theory; Free electron theory; Free-electron model
In solid-state physics, the freeelectron model is a quantum mechanical model for the behaviour of charge carriers in a metallic solid. It was developed in 1927, principally by Arnold Sommerfeld, who combined the classical Drude model with quantum mechanical Fermi–Dirac statistics and hence it is also known as the Drude–Sommerfeld model.
In the British colonies in North America and in the United States before the abolition of slavery in 1865, free Negro or free Black described the legal status of African Americans who were not enslaved. The term was applied both to formerly enslaved people (freedmen) and to those who had been born free (free people of color).