Thermal desorption spectroscopy of Xe at the Si(111) as a local probe for surface structures

Abstract

The binding energy of noble gases depends on the arrangement of atoms close to the adatom. Due to the weak forces of physisorption a rearrangement of the substrate during adsorption is unlikely. Therefore, the desorption of noble gases reveals the local arrangement of surface atoms. It is demonstrated that the structures of the Si(111) surface produced by adsorption of gases or metal overlayers have besides the well-known long range order quite different desorption spectra which point to specific short range order or local atom arrangements.

Selective Ablation of Xe from Silicon Surfaces: Molecular Dynamics Simulations and Experimental Laser Patterning

“…An important observation in the simulations discussed above is the slow rate of the energy transfer from the Si substrate heated by the 16 MW/cm 2 laser pulse up to ∼650 K and the Xe film that heats up to only less than half of that temperature on the nanosecond time scale. The maximum surface temperature is way above the standard desorption temperature (57 K) observed in temperature-programmed desorption (TPD) experiments of Xe from solid surfaces, typically performed at slow heating rates of about 2 K/s and under ultrahigh vacuum conditions. ,,, This large difference can be attributed to the difference in the substrate heating rates. Indeed, Xe multilayers ablate from ruthenium surfaces at ∼350 K when the heating is induced by 5 ns pulse irradiation at λ = 532 nm and absorbed laser power of 2.5 MW/cm 2 , while the resistive heating (∼2 K/s) results in multilayer desorption at 57 K .…”

“…The maximum surface temperature is way above the standard desorption temperature (57 K) observed in temperature-programmed desorption (TPD) experiments of Xe from solid surfaces, typically performed at slow heating rates of about 2 K/s and under ultrahigh vacuum conditions. 30,35,48,49 This large difference can be attributed to the difference in the substrate heating rates. Indeed, Xe multilayers ablate from ruthenium surfaces at ∼350 K when the heating is induced by 5 ns pulse irradiation at λ = 532 nm and absorbed laser power of 2.5 MW/cm 2 , while the resistive heating (∼2 K/s) results in multilayer desorption at 57 K. 35 Similarly, the vast difference between the desorption temperature in nanosecond pulsed laser desorption (heating rate of 10 8 K/s) and standard TPD (2 K/s) was observed in MD simulations of water desorption from metallic surfaces.…”