Material-specific detection and classification of single nanoparticles.

Detection and classification of nanoparticles are important for environmental monitoring, contamination mitigation, biological label tracking, and biodefense. Detection techniques involve a trade-off between sensitivity, discrimination, and speed. This paper presents a material-specific dual-color common-path interferometric detection system. Two wavelengths are simultaneously used to discriminate between 60 nm silver and 80 nm diameter gold particles in solution with a detection time of τ ≈ 1 ms. The detection technique is applicable to situations where both particle size and material are of interest.