Fig. 1. Spectral characteristics of GeuSap and Sapphire.

a Fluorescence decay of GeuSap (orange) on 400 nm excitation and 510 nm detection, measured with TCSPC. The model used for fitting (black) is a bi-exponential function with reconvolution, yielding two lifetimes τ₁ = 0.58 ns (70%) and τ₂ = 1.7 ns (30%). IRF is in gray. Weighted residuals are shown in the bottom panel (χ ² = 1.2). b Fluorescence decay of Sapphire (blue). The model used is a mono-exponential function with reconvolution (black), τ = 3.3 ns and χ² is 1.08. c Absorption spectra of GeuSap and Sapphire. d Emission spectra of GeuSap and Sapphire upon excitation at 400 nm. Optical density at the excitation wavelength was adjusted to 0.1 for both samples. Inset shows normalized emission spectra. W. Res.: weighted residuals. Source data are provided as a Source Data file.