BW scattered intensities under these conditions are of equal strength and normalize all spectra according to this reference.

#### Incident and detection angles: {#incident-and-detection-angles .unnumbered}

The upper limit for the incident angle from the dark-field condensers (FW and BW both $\text{NA}=0.95$) is $$\varphi_{\text{in}} = \sin^{-1}\left( \text{NA} \right) \approx 72^{\circ}.$$ The high incident angles can modify the response of the Mie resonances. However, since the illumination is conic, only a fraction of the incident light has actually a large wavevector component parallel to the nanowire $k_{\parallel}$. Thus, assuming normally incident plane wave illumination in the simulations is a valid approximation to our experimental conditions, further justified by the excellent agreement between our simulations and measurements.

The upper limits of the detection angles can be calculated by the collecting objectives’ numerical apertures: $$\begin{aligned}
  \text{NA}_{\text{FW}} & = 0.75 
    \quad & \Rightarrow \quad 
  \varphi_{\text{FW}} &\approx 49^{\circ}\\
    \text{NA}_{\text{BW}} & = 0.5 
    \quad & \Rightarrow \quad 
  \varphi_{\text{BW}} &\approx 30^{\circ}.
 \end{aligned}$$ With the maximum incident angle $\varphi_{\text{in}} \approx 72^{\circ}$ this eventually leads to the following angular detection ranges (per polar quadrant): $$\begin{aligned}
  23^{\circ}\ & \ \lesssim \varphi_{\text{col., FW}} \lesssim \ & \ 120^{\circ} & \\
    42^{\circ}\ & \ \lesssim \varphi_{\text{col., BW}} \lesssim \ & \ 102^{\circ} &.
 