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Step degeneracy and step-step interactions
A244 Surface Science 283 (1993) 277 282 North-Holland
Many-atom interactions in metals J.K. N0rskov, K.W. Jacobsen, P. Stoltze and L.B. Hansen l.aboratory of Applied Physics, Technical Unit,ersity o1" Denmark, DK 2800 Lyngby, Denmark Received 21 April 1992; accepted for publication 8 May 1992 A conceptual framework is presented for understanding the many-atom interactions in metals. The discussion is based on the effective medium theory. A number of examples are discussed where p h e n o m e n a at metal surfaces are dominated by many-atom interactions: a d a t o m - a d a t o m interactions, nucleation and growth, and reconstructions.
Surface Science 283 (1993) 283-289 North-Holland
New views on surface melting obtained with STM and ion scattering J.W.M. Frenken, H.M. van Pinxteren and L. Kuipers FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, Netherlands Received 21 April 1992; accepted for publication 6 May 1992 This paper gives a brief account of three new p h e n o m e n a related to the disordering process known as surface melting. Using scanning tunneling microscopy we demonstrate that under the influence of the attractive tip-surface interaction, a melting surface can jump to contact and form a connecting neck to the tip. We employ medium-energy ion scattering to show that not all surfaces can be classified simply as either melting or non-melting. We find surface orientations exhibiting incomplete surface melting and we identify ranges of surface orientations that undergo surface-melting induced faceting.
Surface Science 283 (1993) 290-299 North-Holland
Step degeneracy and step-step interactions S. Balibar, C. Guthmann and E. Rolley Laboratoire de Physique Statistique, Ecole Normale Sup~rieure. 24 rue Lhomond, 7.523l Paris Cedex 05, France Received 21 April 1902: accepted for publication 27 April 1992 When slightly misoriented with respect to a high symmetry direction, crystal surfaces are usually called vicinal. However, they should be called so only if they can be described as a set of terraces limited by well separated, weakly interacting, steps. Such a situation occurs if the step width w is much smaller than the average s t e p - s t e p distance d, i.e. if the tilt angle 4' of the vicinal surface is smaller than a small angle ~bc. For ~ > ~bc, the steps overlap and are degenerate. For ~b < qSc, the steps are far enough from each other to be non-degenerate. The critical angle &c tends to zero at the roughening temperature T R where the width w diverges. As shown by recent work on helium crystals, even if T << T~, ~bc is much smaller than previously thought (2.5 ° in this particular case). The two surface stiffness components of truly vicinal surfaces are predicted to be very different from each other (the vicinal surface is highly anisotropic); they are also directly related to the magnitude of s t e p - s t e p interactions; We present a review on crystal shapes, crystallization waves and step fluctuations, and explain why, in our opinion, no clear evidence of a l / d 2 interaction between steps has yet been obtained. The step degeneracy transition at ~bc has not yet been observed either, although it should have drastic effects on the surface stiffness and growth rate of the crystal.
Many-atom interactions in metals J.K. N0rskov, K.W. Jacobsen, P. Stoltze and L.B. Hansen l.aboratory of Applied Physics, Technical Unit,ersity o1" Denmark, DK 2800 Lyngby, Denmark Received 21 April 1992; accepted for publication 8 May 1992 A conceptual framework is presented for understanding the many-atom interactions in metals. The discussion is based on the effective medium theory. A number of examples are discussed where p h e n o m e n a at metal surfaces are dominated by many-atom interactions: a d a t o m - a d a t o m interactions, nucleation and growth, and reconstructions.
Surface Science 283 (1993) 283-289 North-Holland
New views on surface melting obtained with STM and ion scattering J.W.M. Frenken, H.M. van Pinxteren and L. Kuipers FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, Netherlands Received 21 April 1992; accepted for publication 6 May 1992 This paper gives a brief account of three new p h e n o m e n a related to the disordering process known as surface melting. Using scanning tunneling microscopy we demonstrate that under the influence of the attractive tip-surface interaction, a melting surface can jump to contact and form a connecting neck to the tip. We employ medium-energy ion scattering to show that not all surfaces can be classified simply as either melting or non-melting. We find surface orientations exhibiting incomplete surface melting and we identify ranges of surface orientations that undergo surface-melting induced faceting.
Surface Science 283 (1993) 290-299 North-Holland
Step degeneracy and step-step interactions S. Balibar, C. Guthmann and E. Rolley Laboratoire de Physique Statistique, Ecole Normale Sup~rieure. 24 rue Lhomond, 7.523l Paris Cedex 05, France Received 21 April 1902: accepted for publication 27 April 1992 When slightly misoriented with respect to a high symmetry direction, crystal surfaces are usually called vicinal. However, they should be called so only if they can be described as a set of terraces limited by well separated, weakly interacting, steps. Such a situation occurs if the step width w is much smaller than the average s t e p - s t e p distance d, i.e. if the tilt angle 4' of the vicinal surface is smaller than a small angle ~bc. For ~ > ~bc, the steps overlap and are degenerate. For ~b < qSc, the steps are far enough from each other to be non-degenerate. The critical angle &c tends to zero at the roughening temperature T R where the width w diverges. As shown by recent work on helium crystals, even if T << T~, ~bc is much smaller than previously thought (2.5 ° in this particular case). The two surface stiffness components of truly vicinal surfaces are predicted to be very different from each other (the vicinal surface is highly anisotropic); they are also directly related to the magnitude of s t e p - s t e p interactions; We present a review on crystal shapes, crystallization waves and step fluctuations, and explain why, in our opinion, no clear evidence of a l / d 2 interaction between steps has yet been obtained. The step degeneracy transition at ~bc has not yet been observed either, although it should have drastic effects on the surface stiffness and growth rate of the crystal.