Nondestructive high-resolution and absolute mass determination of single charged particles in a three-dimensional quadrupole trap

Abstract

A method for the nondestructive high-resolution and absolute mass determination of charged particles is described. It is based on the detection of light scattered from a single particle in an electrodynamical three-dimensional quadrupole trap. From the amplitude modulation of this signal, the eigenfrequencies of the secular motion are determined with high precision. For 500 nm in diameter SiO2 particles, having a mass of 130 fg (≈1011 u), a resolution of 10−4 is achieved in a 10 s measurement. On a longer time scale, the 10−6 range can be accessed. Key features of the method such as reproducibility, long term stability, accuracy, and linearity are characterized in detail. The extension of the mass range of quadrupole traps from atomic masses to micrometer sized particles as well as potential applications are discussed.