Optical pumping

As optical pumping is called a physical effect that causes a population inversion by optical excitation ( electron-photon interaction). A population inversion is when the energy levels of a particle are not so occupied with electrons, as would be expected without optical excitation according to the given temperature. The technique was developed by Alfred Kastler (Nobel Prize 1966) in the early 1950s.

On the " pumpability " of levels have different properties of the system of energy levels and excitation system influence. These are:

• Temperature of the system, and thus occupation of the levels according to the Boltzmann distribution
• Excitation rate
• Lifetime of the states in the excited level
• Possibly life of the states of the energy levels of the empties the pumped level

Technical Terms

Laser

In lasers called optical pumping the first step in which the optically active medium (e.g., dyes, crystals) (for example, other lasers, flashlamp ) excited by an external energy source in the cavity, that is, the electrons in the case of "lifted" to a higher energy level (optical response ). Technical lasers are typically operated at ambient temperatures, therefore, the critical condition for the optical pumping, the existence of long-lived energy levels, either pumped or level in the indirectly inflated levels.

Resonance spectroscopy

The optical pumping of the underlying mechanisms may be used in addition to the technical use of the laser in certain resonance spectroscopy studies. By cooling the sample to be examined and the use of high excitation rates " nonequilibrium occupations are created " can be used in a large number of systems and they are excited to luminescence.

Since energy levels may be influenced by additional field effects ( static magnetic fields, static electric fields ), the luminescence of the pumped levels are used to:

• To determine properties pumped levels
• To analyze transfer processes at other levels

If additional exchange fields are used, optically pumped level (eg microwave resonance) can also be emptied via additional resonance effects. This leads to so-called multi-resonance measurement methods (e.g., optically detected magnetic resonance - ODMR ).