Photoluminescence (PL) emission spectra were recorded on a FLS980 PL spectrometer from Edinburgh Instruments. Two different measuring assemblies, i.e. the standard right angle geometry for liquid dispersions as well as a front-facing sample holder suitable for powder samples, were used.
FT-IR spectra of ZnO nanoparticle powders were measured in transmission mode using a high-vacuum cell developed by J.T. Yates Jr. and coworkers [27 ]. The sample powders were pressed into a tungsten grid that subsequently was mounted in the high-vacuum cell. The cell was aligned in the optical path of the IR beam of a Bruker Tensor 27 spectrometer system. The resolution was 3 cmτ and 20 interferograms were averaged for a reasonable signal-to-noise ratio.
For IR measurements of aqueous solutions, we used a glass cell in contact with the ZnSe prism that was placed in an ATR reflection unit (PIKE Technologies, Veemax II). This unit was attached to a Bruker Vertex 70 FT-IR spectrometer equipped with a MCT detector. Measurements were performed at an incident angle of 55° using unpolarized light. Spectra were obtained by averaging 100 scans at a resolution of 4 cmτ and are represented as — log(R/R0), where R0 and R correspond to the reflectance values of the reference and the sample, respectively.
FT-IR spectra of ZnO nanoparticle powders were measured in transmission mode using a high-vacuum cell developed by J.T. Yates Jr. and coworkers [27 ]. The sample powders were pressed into a tungsten grid that subsequently was mounted in the high-vacuum cell. The cell was aligned in the optical path of the IR beam of a Bruker Tensor 27 spectrometer system. The resolution was 3 cmτ and 20 interferograms were averaged for a reasonable signal-to-noise ratio.
For IR measurements of aqueous solutions, we used a glass cell in contact with the ZnSe prism that was placed in an ATR reflection unit (PIKE Technologies, Veemax II). This unit was attached to a Bruker Vertex 70 FT-IR spectrometer equipped with a MCT detector. Measurements were performed at an incident angle of 55° using unpolarized light. Spectra were obtained by averaging 100 scans at a resolution of 4 cmτ and are represented as — log(R/R0), where R0 and R correspond to the reflectance values of the reference and the sample, respectively.