Spatial localization of high-frequency particle oscillations in a complex plasma monolayer

We study the spatial distribution of dynamical properties in a strongly coupled confined experimental dust monolayer with a dense central region and a rarefied periphery. We show that the dust particle oscillations spectrum shifts into the low-frequency range from the center of the structure toward its periphery. Correspondingly, the high-frequency particle oscillations are localized in the central region of the system. This effect is quantitatively described within the framework of the model system of trapped screened Coulomb charges. Such spatial localization has a significant effect on the spatial distribution of dynamical parameters, such as the amplitude of particle oscillations and the coupling parameter. The obtained results might be useful for the theory of crystal formation, instabilities and phase transitions in complex (dusty) plasmas, colloidal suspensions, and Coulomb crystals.