Motion of individual atoms and mesoscopic structural dynamics on non-equillibrium surfaces

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In order to realize the direct observation of the dynamic motion of individual atoms and molecules on the non-equillibrium surfaces and to understand the underlying microscopic mechanism, we have developped a new variable-temperature scanned probe microscope. In order to study further on the surface dynamics, we have also conducted thermal desorption and high-resolution electron energy loss spectroscopy to investigate the ordering in the (NO+CO) coadsorption system on the Pd (100) surface.The scanned probe microscope developped in the present study can be operated under ultrahigh vacuum and at sample temperature from 100 to 1000K.Another important characteristic is its low-noise signal output. The vertical noise for the topographic imaging mode is 3pm (p-p), which enables the imaging of (100) and (111) surfaces of transition metals. This microscope can also be operated at tunneling current as low as 1pA, which enables imaging of low-conductivity materials such as organic crystals.The ordering in (NO+CO) /Pd (100) coadsorption system has been studied by low-energy electron diffraction, thermal desorption and vibrational spectroscopy preparatory to the application of the scanned probe microscope. We have found that NO and CO form stable mixed ordered phases and that an explosive CO2 formation reaction undergoes in the mixed ordered phases. A kinetic Monte Carlo simulation based on a lattice-gas model has been done to quantify NO-CO intermolecular interactions.We have also investigated on the H+H/Pd (100) reaction and found that the impinging H atoms force the preadsorbed H atoms to penetrate into Pd bulk (stamping absorption). The characteristics of the potential energy surface for the MH2 system was discussed.