Temporal concentration

The shortest events ever created by man are obtained by lasers interacting with gases. Currently, these time periods are less than a femtosecond. Phase-synchronised (mode-locked) lasers usually produce picosecond or femtosecond (commercial lasers) pulses, which are markedly shorter than the events to be analysed. They can thus be used to sample temporally a very fast phenomenon, such as a chemical reaction involving the formation of free radicals.

Q-switched lasers (nanosecond pulses) can be used to immobilise particles in a gas or a moving machine part (the stroboscope effect). The temporal concentration enables instantaneous electrical fields to be achieved, which can be greater than the fields of atomic bonds in a molecule or a metal. It is therefore possible to create plasmas or to detach atoms from a surface without producing any warming.