Characterization of luminescent chromophore obtained from silica spheres

•Blue light emitting chromophore is separated from the silica spheres.•The chromophore absorption peak is at 5.17 eV.•The luminescent fragment is comprised of C–OH, –CH2, –CH3, –C=O, and Si–O–Si.•Large Stokes shift (201 nm) is observed from the chromophore.

Blue light emitting chromophores have been separated from silica spheres by soaking them into acetone for 120 days. The luminescent chromophores were not obtained from other solvents, including ether, methanol, ethanol, 2-propanol, chloroform and tetrahydrofuran. According to the Fourier transform infrared spectrum, the luminescent material is composed of C–OH, –CH2, –CH3, C=O, and Si–O–Si. UV–visible absorption peak of the chromophore is at 5.17 eV (240 nm). Field emission scanning electron microscope images show small cracks on the surface of aged spheres. The luminescence peak was at 2.81 eV (441 nm) for excitation energy between 3.88 and 3.35 eV and slightly shifted toward lower energy for excitation energy lower than 3.35 eV. The deconvoluted luminescent spectrum shows two emission bands at 3.08 and 2.74 eV, which are well-matched the oxygen deficient center model. Compared to the absorption peak (5.17 eV) and the emission peak (2.81 eV), large Stokes shift (2.36 eV) is observed.

Graphical abstractThe luminescent chromophore was separated from the silica spheres and analyzed the chromophore. Large Stokes shift was observed from this chromophore.Figure optionsDownload full-size imageDownload as PowerPoint slide