Fig. 2: Quantitative nanoparticle characterization.
a Cavity frequency shift Δν and peak transmission amplitude T/T0 as a function of time produced by a single SiO2 nanoparticle. b Schematic sketch of a single nanoparticle diffusing through the standing wave cavity field. c Correlation of cavity frequency shifts and transmission reductions. Solid black line: mean transmission reduction for a given frequency shift. Solid lines: simulation for the nanoparticle’s refractive indices nNP = {1.41, 1.42, 1.43} (yellow, orange, purple). d Histograms for the measured frequency shifts of a single transit event (black data) also shown in Fig. 3b, 59 transits (blue data, measurement duration: 2 h) and 210 additional transits (gray data, 8 h). The observed increased shifts reveal agglomeration. Dotted lines: simulation for nNP = 1.43 and the hydrodynamic radii rhydr = {77.4, 82.3} nm (red, orange). The vertical solid red and orange lines depict the corresponding estimated dimer shifts.
