SPECTROSCOPIC STUDIES OF CHALCOGENIDE GLASS MEMBRANES OF CHEMICAL SENSORS - LOCAL-STRUCTURE AND IONIC RESPONSE

Enhanced chemical durability, suitable and variable transport characte ristics, actually unlimited ability to be doped or modified thus chang ing their structure and properties suggest an application of non-cryst alline chalcogenides and chalcohalides (bulk glasses and thin films) a s promising membrane materials for conventional chemical sensors and c hemical microsensors selective to heavy metal ions in various liquid m edia. Furthermore, they can be used as convenient model materials for a better understanding of fundamentals of the ionic response. Relation ships between composition, local structure, ionic and electronic trans port phenomena, on the one hand, and surface-ion exchange and ionic re sponse, on the other hand, are the main topics to be discussed in the present contribution. Mossbauer spectroscopy and surface spectroscopy studies allow important information to be obtained concerning the shor t- and medium-range order in the glasses as well as surface processes occurring at the glass/solution interface. It will be shown that diffe rent microstructural organizations of the glass membrane (glass-networ k topology, chemical and structural states of the components, etc.) le ad to drastically different transport, exchange and sensor properties. Structural and mechanistic studies of this kind are, therefore, extre mely important for further development and optimization of chalcogenid e glass chemical sensors.