Figure 1

(a) Experimental detection scheme. F: filter; D: dichroic mirror; P: polarizing beamsplitter; O: microscope objective ($\times 60$, $\mathrm{N}.\mathrm{A}.=1.4$); APD1, APD2: silicon avalanche photodiodes. The 3D plot shows an optical SHG intensity raster scan of a $7.6\mu \mathrm{m}\times 7.6\mu \mathrm{m}$ area. Each spot, whose diameter of about 400 nm is limited by diffraction, is associated with an isolated CMONS nanocrystal. The higher peak signal corresponds to 300 counts integrated over 20 ms. (b) Orientation of the unit-cell frame $(a,b,c)$ in the macroscopic frame $(X,Y,Z)$. The $(x,y,z)$ axes relate to the nanocrystal frame with $(x,y)$ defining the unit-cell plane (see Fig. 2).Reuse & Permissions

Figure 2

Molecular structure of CMONS and unit-cell representation of the crystalline form $(a)$, adapted from Ref. 11. The unit cell is constituted by four CMONS dipoles tilted with an angle of $\pm 25.5°$ relative to the $(c)$ axis. The table shows the nonvanishing coefficients of the microscopic susceptibility tensors of the CMONS unit cell. All out-of-plane contributions involving the index $(a)$ can be neglected, as one can assume that the molecules lie in the $(b,c)$ plane of the unit cell [11]. The coefficients are normalized so that their tensorial norm is equal to unity. Nondiagonal coefficients are equal for permutations on all indices.Reuse & Permissions

Figure 3

TPF and SHG polarization responses of two monocrystalline nanocrystals in the $X$ and $Y$ analyzed polarization directions (indicated at the bottom of the circles). The data are displayed with similar sizes, although they are of different amplitudes. The fits with the monocrystalline model give the following orientation parameters within a $\pm 5\%$ error range: (a) ($50°$, $60°$, $70°$); (b) ($80°$, $80°$, $110°$). These angles are defined within the $[0,180°]$ angular range. Note that the combinations $(\theta ,\phi ,\psi )$, $(\theta ,\phi +180°,\psi )$, and $(\theta ,\phi ,\psi +180°)$ give identical polarization responses.Reuse & Permissions

Figure 4

TPF and SHG polarization responses of two nonmonocrystalline nanocrystals in the $X$ and $Y$ analyzed polarization directions. (a) A nearly isotropic nanocrystal. (b) A polycrystalline nanocrystal, for which the polar plot fits are obtained from the incoherent addition of two nanocrystals of orientations ($70°$, $160°$, $60°$) and ($70°$, $55°$, $65°$). This combination of angles is not the unique solution for the fit.Reuse & Permissions