Publications by authors named "Vahid Shahabadi"

Accurate surface tension measurements are key to understanding and predicting the behavior of atmospheric aerosols, particularly their formation, growth, and phase transitions. In Earth's atmosphere, aerosols often exist in metastable states, such as being supercooled or supersaturated. Standard tensiometry instruments face challenges in accessing these states due to the large sample volumes they require and rapid phase changes near surfaces.

View Article and Find Full Text PDF

In this Letter, we study the optical trapping of particles in a focal spot engineered by a combination of a dielectric microsphere and the conventional optical tweezers setup. The dielectric microsphere is placed in the laser path before the focal spot, and its impact on the trapping stiffness is theoretically and experimentally studied in detail. The suggested method for considering the geometric phase shift, due to the presence of the microsphere, into the Debye diffraction integral shows a good agreement with the experiment.

View Article and Find Full Text PDF

In this paper, we study the optical trapping of anti-reflection core-shell microspheres by regular Gaussian beam and several structured beams including radially polarized Gaussian, petal, and hard-aperture-truncated circular Airy beams. We show that using an appropriate anti-reflection core-shell microsphere for the optical trapping by several structured light beams can dramatically enhance the strength of the trap compared to the trapping by the common Gaussian beam. The optimal core-shell thickness ratio that minimizes the scattering force is obtained for polystyrene-silica and anatase-amorphous titania microspheres, such that the core-shells act as anti-reflection coated microspheres.

View Article and Find Full Text PDF