The capture cross section of a dipole trap

An active distance of attraction model is developed for the capture cross section σ_s of a dipole trap, yielding a simple analytical form. A first order analysis of the field dependence shows that the result is valid up to moderately high field strengths, e.g. up to 5 × 10⁶ V m^-1 for the example quoted in the text. It should be borne in mind, however, that this marks the limit of the analysis rather than the actual onset of a pronounced field dependence of σ_s.The assumption of certainty of energy loss by the electron on entering the ?2kT equipotential surface limits the applicability of the result to low mobility solids and certain liquids; fortuitously these happen to encompass the substances predicted to be most suitable as bulk media in dipole capture investigations.