A Radiotracer Study of CadmiumTransport Across the CdS/ Aqueous Solution Interface

Information on interfacial mass transport of cadmium in cadmium sulfide suspensions and er equilibrium conditions has been obtained by probing with a radiotracer for cadmium. The transport of Cd2+ ions from the cadmium sulfide solid particles to the saturated solution and visa versa is followed by adding radioactive 109Cd2+ to the solution and measuring the amount of radioactivity present in the solution as a function of time. The amount of exchangeable cadmium in or at the solid/liquid interface, which is deduced from the final value of radioactivity in the solution appeared to be 1.8 to 2.3 times the amount of cadmium in one lattice layer. Compartmental analysis of the experimental data revealed that 4 different cadmium species are involved in the exchange processes, one of which being the cadmium in the bulk of the solution, and another one, representing 40% to 50 of one lattice layer, which exchanges rapidly with the solution in comparison with the other two species left

Observation of compositional domains within individual copper indium sulfide quantum dots

The origin of photoluminescence in copper indium sulfide (CIS) quantum dots (Qdots) has previously been ascribed to a donor-acceptor pair (DAP) recombination, with a crystal lattice defect implicated as the origin of the donor state. In this study, electron energy-loss spectroscopy (EELS) was used to observe defect-rich compositional domains within individual CIS Qdots, supporting a model of defect-state-mediated photoluminescence for these particles, and identifying them as an ideal model system for future study of lattice defects on Qdot properties

A Radiotracer Study of CadmiumTransport Across the CdS/ Aqueous Solution Interface

Information on interfacial mass transport of cadmium in cadmium sulfide suspensions and er equilibrium conditions has been obtained by probing with a radiotracer for cadmium. The transport of Cd2+ ions from the cadmium sulfide solid particles to the saturated solution and visa versa is followed by adding radioactive 109Cd2+ to the solution and measuring the amount of radioactivity present in the solution as a function of time. The amount of exchangeable cadmium in or at the solid/liquid interface, which is deduced from the final value of radioactivity in the solution appeared to be 1.8 to 2.3 times the amount of cadmium in one lattice layer. Compartmental analysis of the experimental data revealed that 4 different cadmium species are involved in the exchange processes, one of which being the cadmium in the bulk of the solution, and another one, representing 40% to 50 of one lattice layer, which exchanges rapidly with the solution in comparison with the other two species left

Coupled Mach--Zehnder interferometer

InGaAsP photonic integrated circuit. The system acts as an optical flip-flop, with optical set and reset functions. A schematic diagram of the device is shown in Fig. 1. Each MZI in the device is constructed from the following components: a 72 / 28 splitting ratio multimode interference coupler 6 at the MZI input (left side of Fig. 1), a 1450 #m long electro-optic phase shifter (PS) in one MZI arm, 7 a 750 #m long SOA in the other MZI arm, and, following the SOA, another 72 / 28 multimode interference coupler. This coupler is employed to couple light out of the system, such that the system's state can be observed, and also to couple in light that is used to switch between states. The two MZIs share a common 50 / 50 multimode interference coupler. The couplers employ tapered access waveguides for accurate coupling ratios and low excess loss. 8 A theory on the way in which two coupled MZIs can interact to form a 1 bit memory is given in Ref. 5. Here, MZI 1 and MZI 2 share a co