Browsing by Author "Woldeghebriel, Hagos"

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    X-Ray Study of Dynamics of Growing Wetting Films
    (Addis Ababa University, 1996-06) Woldeghebriel, Hagos; Press, Werner (Professor)
    The dynamics of growing wetting films is studied by the method of x-ray scattering in the region of total external reflection. \\"ith a short pulse disturbance caused by a temperature difference between the substrate and the \"apour in the x-ray cell. the wetting film thickness is reduced. Afterwards the time dependence of the -growing film is monitored by x-ray reflectivity measurements. The examined sample systems are H2/Si. CH.3/Si . Ge/Si and a quartz glass wetted by a liquid film of CCk The obsen'ed growth kinetics of the wetting layers are discussed in the framework of a model which is adapted to the experimental conditioll5. particularly the finite temperature stability of the experimental set-up. From the growth law l(t) rx I ~ exp:~(t/T)nl fitted to the data. the time constants T and the dynamic exponent 11 are determined. The quallt ity n depends on the dimension of the growth mechanism