Fig. 3: Orientation analysis of a single NaYF4:Eu nanorod by spectral fitting.
From: Measuring 3D orientation of nanocrystals via polarized luminescence of rare-earth dopants
a–b Schematic illustration of a hexagonal crystalline NaYF4:Eu nanorod with an arbitrary 3D orientation denoted by the spherical angles (θ, φ) or (θ′, φ′) when the polar axis is (a) y-axis or (b) z-axis respectively. The observation plane is fixed as xy-plane. c A scheme of the optical microscopy setup used to conduct the orientation analysis. The inset is a photograph of the photoluminescence (PL) of a single nanorod captured by the CCD camera (scale bar: 1 µm). The in-plane angle (φ′) of the nanorod was found as the long axis of the ellipsoidal shape of this image. d, e Spectral fitting analysis using a polarized PL spectrum Izx or Izy obtained with the analyzer (d) parallel to the x-axis or (e) parallel to the y-axis. Each analysis considers both ED and MD transitions in order to determine θ and φ from a single spectrum using Eqs. 4–9. The calculated values of the trigonometric functions of (θ, φ) and the absolute values of (θ′, φ′) are presented in the figure. The results of the same analysis for a large number of particles are shown in the supplementary information (Supplementary Fig. 8, Supplementary Data 1).
