For the lifetime measurements the samples were excited with a Xe flashlamp (50 Hz repetition rate at 340 nm) for LTCs and with a diode-laser (405.6 nm center wavelength, 2 MHz repetition rate, 5 mW maximum average power) for the QDs. FRET-measurements were performed on an immunoanalysis platereader (IOM Nanoscan LF500, Berthold selleck bio Detection Systems, Germany) with two photomultiplier tube (PMT) detection channels using changeable bandpass filters (Semrock, USA). All samples were excited with a pulsed 337.1 nm nitrogen laser system (SpectraPhysics, USA) with 128 shots
The chemo-resistive detection of reducing gases in n-type oxide semiconductors is determined by various factors such as the degree of electron depletion in nanostructures, the Inhibitors,Modulators,Libraries electron transfer across the necks or grain boundaries, the effective diffusion of analyte gases onto the sensor surface, the amount of oxygen adsorption on the surface, and the surface reaction between analyte gases and negatively charged adsorbed oxygen [1�C8].
Most of the key factors in gas sensing Inhibitors,Modulators,Libraries reactions, except the surface reactions, can be effectively manipulated by proper control of the size, morphology, crystallinity, and agglomerated configuration of the nanostructures used. To achieve high gas responses, nanostructures with small size, high surface area, good crystallinity, macro-, meso- and nano-porosity, and less-agglomerated configurations are advantageous [9�C13].ZnO is one of the most representative chemo-resistive n-type oxide semiconductors.
Many synthetic routes to prepare ZnO nanostructures Inhibitors,Modulators,Libraries have Inhibitors,Modulators,Libraries been suggested, which include hydrothermal reactions [14�C16], ambient-atmosphere solution reactions at mild temperature (50�C100 ��C) [17�C19] or room temperature [20,21], thermal evaporation [22], and microwave methods [23]. Among these, solution-based self-assembly reactions under ambient atmosphere provide facile and cost-effective methods to prepare various ZnO nanostructures with high surface areas. When the low-dimensional nano-building blocks such as 1-dimensional (1D) nanorods and 2D nanosheets are self-assembled into the higher dimensional hierarchical structures, well-defined Dacomitinib porous architectures can be achieved without sacrifice of high surface area. Thus the gas response, as well as the response kinetics, selleck kinase inhibitor can be enhanced significantly by the rapid and effective diffusion of analyte gases to the entire sensing surface [24�C26].The present authors have previously prepared ZnO hierarchical nanostructures assembled from dense nanosheets by the forced stirring of immiscible mixtures of oleic-acid-dissolved n-hexane solutions and aqueous solutions of dissolved Zn-precursors and subsequent addition of NaOH [27].