Organic film sources

Individual valves switch the source flows to enable rapid on/off control of the respective deposition, which offers high precision control of layer interfaces and minimization of material waste. The organic molecules are homogeneously mixed in the gas phase before being introduced uniformly through the heated showerhead injector across the entire substrate surface where they condense to form the desired organic film. 

Broadly speaking, there are three different types of liquid membranes. Bulk liquid membrane (BLM) is a stirred organic phase of lower density than the aqueous phase positioned under it or vice versa. In emulsion liquid membrane (ELM), the receiver aqueous phase containing oil droplets is dispersed into the feed aqueous phase. The total volume of the receiving phase inside the oil droplets is at least ten times smaller than that of the source phase. The thickness of the membrane (organic film) is very small, while the surface area is enormous resulting in very fast separations. Though the efficiency of mass transfer in the liquid membranes is inversely proportional to the thickness of the membrane phase, too thin a film has poor stability due to low but finite solubility in F and R. It can also be disturbed by pressure differences created by the two aqueous phases. 

Organic films on sapphire were prepared in various UHV chambers with base pressures of less than 5 x 10 ° mbar. Chemical composition and cleanliness of all samples were determined with XPS using Mg-Ka radiation from a laboratory source and a hemispherical electron analyser. The preparation and characterisation of the sapphire substrates are discussed in Section 14.3.1.1. 

Fig. 12.13 An organic thin-film field-effect transistor, schematic. The current Id in a weakly semiconducting organic film (black) between two electrodes S (source) and D (drain) can be controlled by the gate (G) voltage Vc- The latter influences charge carriers capacitively in a thin layer of the...

Diesel particulate emissions are a major source of fine and ultrafine atmospheric particles. These particles are of current interest due to their suspected adverse health effects and their impacts on the Earth s radiation balance, visibility impairment, and atmospheric chemistry. Diesel particles are typically aggregates of fine primary particles coated with condensed organic films. The most common technique to characterise the structure of the aggregates is TEM, which provides projected two-dimensional properties of aggregates. Thus, the actual structural properties of aggregates are inferred from the projected properties. However, few studies of the structural properties of aggregates produced from diesel engines have been reported. 

---