As-synthesized α-SeNPs are shown in Figure , panel A with a fast Fourier transform of the image (FFT) shown in the inset. The FFT shows no distinct diffraction spots or rings, indicating that the sample is amorphous. When the α-SeNPs are converted to ZnSe (Figure , panel B) or CdSe (Figure , panel C), we directly observe lattice lines within the NPs as well as diffraction spots and rings in the FFTs (insets). Figure , panels D -F show the visual appearance of the nanoparticle solutions upon exposure to UV irradiation. The α-SeNP precursors are not substantially fluorescent (panel D). Following conversion to ZnSe (Figure ) or CdSe (Figure ), the solutions become luminescent, indicating the presence of semiconductor nanoparticles.