Thermal conductivity image

Figure 4. Left - topography of microtomed cross-section through a multilayer polyolefin packaging film. Centre - raw thermal conductivity contrast image. Right - thermal conductivity image postprocessing with trained neural net program.

Sowada and Warman (1982) have described a dc conductivity method for Ar gas at 295 K and 45 atm. Following a 20-ns pulse of irradiation, the conductivity rises to a peak at -50 ns, due to the Ramsauer effect, before settling to a plateau, which is ascribed to thermal conductivity since the collecting field is very low. Since there is little electron loss, the conductivity profile is proportional to the mobility profile this in turn can be considered a kind of image of collision frequency as a function of electron energy. The time to reach the conductivity plateau, -150 ns, is the measure of thermalization time in the present case. At a density of -9 X 1021 cm-3, the conductivity maximum vanishes, indicating the disappearance of the Ramsauer minimum according to Sowada and Warman. 

Low density PE foam sheets having a thickness of 10 mm were cut from a block produced by compression moulding and their thermal conductivities over the temperature range from 24 to 50C determined. The evolution of the properties along the block was analysed and the cell structure, apparent mean cell diameter, anisotropy, mean cell wall thickness and relative fraction of polymer determined using quantitative image analysis and a previously reported model utilised to predict the thermal conductivity of the foams. 30 refs. 

In order to obtain a fundamental understanding of oxide surfaces, well-ordered thin oxide films, grown in ultrahigh vacuum (UHV) under well-controlled (clean) conditions, has turned out to be a successful approach ([8, 17, 38] and references therein). In contrast to many (insulating) bulk oxides, thin oxide films exhibit electrical and thermal conductivity sufficient for the application of surface sensitive imaging (e.g., STM) and spectroscopic methods (e.g., XPS Auger electron spectroscopy, AES and temperature-programmed desorption, TPD). 

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