Wetting Phenomena of Mercury near the critical point

It is well known that liquid mercury is a non-wetting substance on solid non-metallic substrate under the ambient conditions。Indeed the closest example in common experience of a non-wetting substance is a mercury drop on a glass plate.However，at high temperatures and high pressures close to the liquid-vapor critical point of mercury，we found that sapphire substrate is wetted with mercury.This change from non-wetting to wetting takes place as a1st order phase transition，and is called a wetting transition.In the present study，we tried to develop the above study further.We invented a new experimental technique for ellipsometric measurements，which can be applied to high temperature and high pressure conditions。By using this technique，we succeeded in determining important physical quantities，such as coverageΓ，which is the order parameter of the wetting transition.This technique makes us possible to study the physical properties of the wetting layer as an two-dimensional liqu…More id，and we concluded that the wetting layer has semiconducting properties.This result gives important information on the problem why the sapphire substrate is wetted by mercury。In addition，we found that the wetting phenomena can also be detected by measuring the thermal radiation intensity.Indeed，a sharp dip in the thermal radiation intensity is observed in the prewetting supercritical region，where the two-dimensional compressibility(αΓ/αµ)ii D2τii is expected to show a maximum due to the critical fluctuations。Hereµis the chemical potential.As stated above，we invented new experimental techniques，by which we can determine experimentally both the mean values and the fluctuations of physical quantities characterizing the wetting phenomena with high accuracy.These techniques are expected to be applied not only to sapphire-mercury system but also to other systems.The results of the present research project are reported in“Adriatico research conference on wetting”(Treste，Italy)as an invited lecture.The head investigator of the present research project organized a symposium on“wetting phenomena”in the meeting of the physical society of Japan for the first time.Less：Less

It is well known that liquid mercury is a non-wetting substance on solid non-metallic substrate under the ambient conditions. Indeed the closest example in common experience of a non-wetting substance is a mercury drop on a glass plate. However, at high temperatures and high pressures close to the liquid-vapor critical point of mercury, we found that sapphire substrate is wetted with mercury. This change from non-wetting to wetting takes place as a 1st order phase transition, and is called a wetting transition.In the present study, we tried to develop the above study further. We invented a new experimental technique for ellipsometric measurements, which can be applied to high temperature and high pressure conditions. By using this technique, we succeeded in determining important physical quantities, such as coverage Γ, which is the order parameter of the wetting transition. This technique makes us possible to study the physical properties of the wetting layer as an two-dimensional liqu … More id, and we concluded that the wetting layer has semiconducting properties. This result gives important information on the problem why the sapphire substrate is wetted by mercury. In addition, we found that the wetting phenomena can also be detected by measuring the thermal radiation intensity. Indeed, a sharp dip in the thermal radiation intensity is observed in the prewetting supercritical region, where the two-dimensional compressibility (αΓ/αμ)ィイD2τィエD2 is expected to show a maximum due to the critical fluctuations. Here μ is the chemical potential.As stated above, we invented new experimental techniques, by which we can determine experimentally both the mean values and the fluctuations of physical quantities characterizing the wetting phenomena with high accuracy. These techniques are expected to be applied not only to sapphire-mercury system but also to other systems. The results of the present research project are reported in "Adriatico research conference on wetting" (Treste, Italy) as an invited lecture. The head investigator of the present research project organized a symposium on "wetting phenomena" in the meeting of the physical society of Japan for the first time. Less