Fls980 fluorometer

Transmission electron microscopy (TEM) was carried out on a JEOL-2010 TEM at 200 kV. Fourier transform infrared (FTIR) spectra were recorded using a FTIR2500 spectrometer (KBr disk). Raman spectra were collected on a LabRam-1B Raman spectroscope equipped with a 632.8 nm laser source. X-ray diffraction spectra (XRD) were determined on a Holland PANalytical X'Pert PRO X-ray diffractometer with Cu Kα (λ = 1.54056 Å) as radiation source in the 2θ range of 5–80°. X-ray photoelectron spectroscopy (XPS) measurements were made on Kratos AXIS UltraDLD (Kratos Analytical Ltd.) with mono Al Kα radiation (hν = 1487.71 eV) at a power of 75 W. Emission spectra were collected using a Varian Cary 100 spectrometer. Fluorescence life time of the products were determined using a FLS980 fluorometer (Edinburgh Instruments Ltd.). Absorption spectra were recorded on a UV-3600 UV-vis-NIR spectrophotometer (Shimadzu). Fluorescence quantum yield (QY) was detected using quinine sulfate as the standard (QY = 54% in 0.1 M H₂SO₄). Confocal laser-scanning microscopy (CLSM) images were recorded on a Zeiss LSM 710 CLSM (Zeiss LSM710, Germany). The zeta potential of Mn(ii)-NGQDs and NG were measured by a Zetasizer Nano ZS90 (Malvern Instruments).