Intermolecular Forces from Atomic Line-Shape Experiments

A systematic convergent method of studying intermolecular forces in excited states is detailed. Extensive comparison between theory and experiment indicates that high-resolution line-shape experiments over a wide range of frequencies will permit the inference of parameters in realistic forms of the potential energy. The analysis focuses on the ²P1/2-²S1/2 resonance line of cesium pressurized by helium, argon, and xenon. When the model is used with ground-state potentials inferred from atomic-beam experiments, and when the excited state is described by V=GR¹²-DR⁶, the following reliable parameters were determined: helium, G=0.459±0.060 and D=-0.614±0.061; argon, G=6.48±0.20 and D=5.23±0.05; xenon, G=53.6±5.8 and D=19.1±0.57, where the units of G are 10^-102 erg cm¹² and of D are 10^-58 erg cm⁶.