Analytics
Aim
The physical and chemical characterization of samples from materials science with established methods is an important tool in scientific work. In case of nanomaterials the optical properties are characteristic due to quantum size effects. Optical measurements reveal information about the electronic structure. Additionally, nanomaterials are characterized by a large surface area. A non-destructive method to investigate this feature uses gas adsorption.
Synthesis of nanomaterials in the IVG labs is mostly based on gas-phase processes. The determination of chemical pathways often requires a detailed chemical analysis. For this purpose, a combination of gas chromatography and mass spectrometry (GC/MS) is a powerful tool. It enables to analyze mixtures as well as pure substances. GC/MS allows a quantitative determination.
Approach
The optical properties of materials are characterized by the optical absorption and the fluorescence. In our lab, the former can be measured with a Cary 400 UV-Vis-spectrometer while the fluorescence can be analyzed by means of a FluoroLog FL3 fluorescence spectrometer. High quality spectra are achieved by using double monochromators and a detector equipped with a Peltier cooling. The quantum yield can be determined by means of an integrating sphere. Both devices are also equipped with special sample holders for powders. The gas adsorption is measured with nitrogen at 77 K with a Quantachrome Nova 2200 analyzer. The instrument is equipped with two outgassing and one measuring station. A detailed determination of the adsorption isotherm can be used to receive information about the pore size of the material. For GC/MS measurements an Agilent GC 7890 N attached to a MSD 5975 mass analyzer is available and liquid as well as gaseous samples can be analyzed. For highly sensitive detection of hydrocarbons there is also a flame ionization detector available.