Thermalisation

In physics, thermalisation (in American English thermalization) is the process of particles reaching thermal equilibrium through mutual interaction.

When a molecule absorbs energy, as in the technique of molecular fluorescence, the lifetime of the excited state is ~10⁻¹² sec. Then it rapidly loses energy to the lowest level of the lowest excited state; this is called thermalization.

In general the natural tendency of a system is towards a state of equipartition of energy or uniform temperature. This raises the system’s entropy.

Examples of thermalisation include:

• the achievement of equilibrium in a plasma
• the process undergone by high-energy neutrons as they lose energy by collision.

External links

• Collisions and thermalization
• U.S. Nuclear Regulatory Commission Glossary