Anomalous lattice shrink of a single CeO₂submicrometer particle in an optical trap

Anomalous lattice shrink is observed in a single submicrometer-sized CeO₂particle with X-ray diffraction using an optical-trap sample holder. A CeO₂particle 380 nm in size is successfully levitated with radiation pressure force exerted by counterpropagating laser beams and irradiated by a high-flux focused synchrotron radiation beam. The diffraction pattern of a single particle is consistent with that of CeO₂but the lattice shrink approaches 1.22% of the lattice constant of a particle assemblage.