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Surface melting?
A427 Surface Science 189/190 (1987) 605-609 North-Holland, Amsterdam SURFACE
605
MELTING?
G. JEZEQUEL
*, P. T H I R Y , (3. R O S S 1 , K . H R I C O V I N I
**
a n d Y. P E T R O F F Laboratoire pour l'Utilisation du Rayonnement Electromagn~tique, Universit~ Paris Sud. 91405 Orsay, France Received 15 April 1987; accepted for publication 16 April 1987 Recently the observation of a solid-liquid transition has been reported on the (110) surface of lead at 40 K below the bulk melting point and a premelting of Ge (111) at 172°C below the bulk melting temperature. We have performed angle resolved photoemission experiments on Pb(110), AI(100) and G e ( l l l ) near the bulk melting point. No evidence of molten or fully disordered layers has been observed for Pb(ll0), AI(100) and Ge(lll).
610
Surface Science 189/190 (1987) 610-619 North-Holland, Amsterdam
THERMALLY STUDIED
INDUCED
DISORDER
BY LOW-ENERGY
ON A Cu(ll0)
SURFACE
ION SCATTERING
AND INVERSE PHOTOEMISSION Th. F A U S T E R ,
R. S C H N E I D E R ,
H. D U R R ,
G. E N G E L M A N N
a n d E. T A G L A U E R Max-Planck-lnstitut for Plasmaphysik, EURA TOM Association, D-8046 Garching near Munich, Fed. Rep. of Germany Received 30 March 1987; accepted for publication 4 May 1987 The scattering of low-energy Na + ions (600 eV, 0 = 50 o) off a Cu(110) surface along the [110] azimuthal direction shows a strong decrease of the intensity above 450 K. This observation cannot be explained by computer simulations using the regular lattice structure and, therefore, indicates a rearrangement of the surface. Experiments with Ne + ions (5 keV, 0 = 164 o) give a more direct picture of the geometrical surface structure. The results above 500 K suggest larger displacements of the surface atoms than expected from the extrapolation of the vibration amplitudes at lower temperatures. Additional structtires can he interpreted as the creation of adatoms. The intensity of inverse photoemission transitions is found to decrease with temperature stronger than expected from a simple Debye-Waller factor. Taking scattering by defects into account gives a good fit of the experimental data.
605
MELTING?
G. JEZEQUEL
*, P. T H I R Y , (3. R O S S 1 , K . H R I C O V I N I
**
a n d Y. P E T R O F F Laboratoire pour l'Utilisation du Rayonnement Electromagn~tique, Universit~ Paris Sud. 91405 Orsay, France Received 15 April 1987; accepted for publication 16 April 1987 Recently the observation of a solid-liquid transition has been reported on the (110) surface of lead at 40 K below the bulk melting point and a premelting of Ge (111) at 172°C below the bulk melting temperature. We have performed angle resolved photoemission experiments on Pb(110), AI(100) and G e ( l l l ) near the bulk melting point. No evidence of molten or fully disordered layers has been observed for Pb(ll0), AI(100) and Ge(lll).
610
Surface Science 189/190 (1987) 610-619 North-Holland, Amsterdam
THERMALLY STUDIED
INDUCED
DISORDER
BY LOW-ENERGY
ON A Cu(ll0)
SURFACE
ION SCATTERING
AND INVERSE PHOTOEMISSION Th. F A U S T E R ,
R. S C H N E I D E R ,
H. D U R R ,
G. E N G E L M A N N
a n d E. T A G L A U E R Max-Planck-lnstitut for Plasmaphysik, EURA TOM Association, D-8046 Garching near Munich, Fed. Rep. of Germany Received 30 March 1987; accepted for publication 4 May 1987 The scattering of low-energy Na + ions (600 eV, 0 = 50 o) off a Cu(110) surface along the [110] azimuthal direction shows a strong decrease of the intensity above 450 K. This observation cannot be explained by computer simulations using the regular lattice structure and, therefore, indicates a rearrangement of the surface. Experiments with Ne + ions (5 keV, 0 = 164 o) give a more direct picture of the geometrical surface structure. The results above 500 K suggest larger displacements of the surface atoms than expected from the extrapolation of the vibration amplitudes at lower temperatures. Additional structtires can he interpreted as the creation of adatoms. The intensity of inverse photoemission transitions is found to decrease with temperature stronger than expected from a simple Debye-Waller factor. Taking scattering by defects into account gives a good fit of the experimental data.