Energy Pooling in Collisions Between Excited Atoms

4 Energy Pooling in Collisions Between Excited Atoms 

Optical pumping with lasers may bring an appreciable fraction of all atoms within the volume of a laser beam passing through a vapor cell into an excited electronic state. This allows the observation of collisions between two excited atoms, which lead to many possible excitation channels where the sum of the excitation energies is accumulated in one of the collision partners. Such energy-pooling processes have been demonstrated for Na -fNa, where reactions 

Measurements of the fluorescence intensity h n, L) emitted by the levels Na n, L =4D or 5S) yields the collision rate 

Since the sum of the excitation energies of the two colliding Na (3P) atoms is higher than the ionization limit of the Na2 molecule, associative ionization 

A further experimental step that widens the application range is the excitation of two different species Ai and A2 with two dye lasers. An example 

A further experimental step which widens the application range, is the excitation of two different species Aj and A2 with two dye lasers. An example is the simultaneous excitation of Na (3P) and K (4P) in a cell containing a mixture of sodium and potassium vapors. Energy pooling can lead to the excitation of high-lying Na or K states which can be monitored by their fluorescence [13.57]. When both lasers are chopped at two different frequencies fj and f2 (where 1/f is long compared to the collisional transfer 

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