Surface phenomena and isotope effects in the process of titanium hydrides (deuterides) formation

Surface phenomena related to the process of TiHx (TiDy) formation at 78K and 298K were studied through simultaneous surface potential (SP) and pressure measurements, by means of sensitive, short response time circuits. Thermal Desorption Mass Spectrometry was applied to compare hydrogen (deuterium) uptake on the surface of titanium hydride (deuteride) and in the bulk. All studies were performed in situ, on thin Ti films deposited under ultra-high vacuum conditions. An image of the Ti film was obtained by Atomic Force Microscopy. It has been found that TiHx (TiDy) is formed following the incorporation of positively polarized hydrogen (deuterium) adspecies from the surface into the bulk of the Ti films. An isotope effect was observed in the rate of incorporation of hydrogen (deuterium) adspecies from the surface to below the surface image plane. The rate of incorporation was found to depend strongly on the H/Ti (D/Ti) atomic ratio in TiHx (TiDy).