Collisional Line Broadening Using Laser Excitation and Ionization

A laser excitation and ionization process is used to measure Cs-Ar interaction forces at long range. With energy densities of 1 J/${\mathrm{cm}}^2$, nonlinear excitation persists as far out as 70 Å at one atmosphere of Ar. This method provides extreme sensitivity (even single absorption events can be measured) which allows absolute measurements on the very far wing where absorption or fluorescence becomes vanishingly small.