A collection of particles, interacting via screened Coulomb pair potentials and confined to two dimensions, is used in a Monte Carlo simulation to study the effect of externally applied potentials on the local order of equilibrium phases. By varying the inverse screening length of the particle potential at fixed surface charge, a liquid to crystal phase transition is observed. These phases are then subjected to a spatially varying external potential and studied as a function of the amplitude and period of this potential. The application of the external (radiation) potential causes the particles to align within the potential minima. The degree of this localization is found to be dependent on the external field amplitude. The particle pair potential produces a variety of local structures depending on the period of the externally applied field. The results of these simulations mimic the observed behavior of two dimensional suspensions of charge stabilized particles subjected to spatially varying radiation pressure fields. There is agreement between these simulations and recent experiments.
