Figure 4

(a,b) Second- and fourth-order P-SHG experimental results for two measured BTO nanoparticles and (c) one modelled nanoparticle. Scale bars: 500 nm (12.5 px). (d) The model parameters are θ = 45° (variable φ and ψ yield identical results), nanocrystal diameter 100 nm (2.5 px), core-to-size ratio r = 0.4, surface to core nonlinearity ratio η = 0.5.