Laser heating of a charged gold nanosphere levitated in an ion trap at high vacuum*

Levitation of a nanoparticle in high vacuum decouples the particle from its environment and enables sensitive thermodynamic measurements; specifically, a levitated particle can be heated in a controlled manner via illumination with a laser. We confine an electrically charged gold nanosphere in a quadrupole electric field trap at pressures as low as 1x10^-8 Torr and illuminate it with a linearly polarized 532 nm laser. Accurate measurements of the particle’s charge-to-mass ratio, combined with observations of single discharge events, give a precise determination of its mass. We observe that the particle begins to evaporate at sufficiently high laser powers; from the evaporation rate, we can deduce its internal temperature. In this talk, we present evidence of the heating of 250 nm gold spheres to temperatures in the range of 1000-1250 K, near the melting temperature of 1337 K. Further heating of the particle should enable trapping and observation of a molten droplet.