X-Ray Scattering Studies of the Melting of Lead Surfaces

X-RAY REFLECTIVITY STUDY OF SURFACE MELTING ON Pb (110)

“…At T = Tm -0.2 K, the QLL thickness is been found to be d=1.96 + 0.25 nm. This value is in good agreement with the ion scattering results (2.15 f 0.15 nm)/3/ but much larger than that of the X-ray study 161. The average density of the QLL is 3.9 + 1.2 % smaller than that of solid Pb.…”

“…Information is obtained on the density profile near the surface. The existence of a quasiliquid layer on top of the Pb(ll0) surface, with average density close to that of bulk liquid is clearly shown at T=Tm-0.2 K. The QLL thicknesses used to fit the reflectivity curves at other temperatures below Tm are consistent with the ion-scattering results /2,3/, but disagree with the conclusions from the X-ray diffraction study by Fuoss et al 161. The reason for the discrepancy is not yet understood.…”

Phase transition of a Pb monolayer on Ge(111)

“…The solidliquid interface that occurs during surface melting 3 is of equal fundamental interest, but here also the precise structure of the liquid remains unknown. 4,5 Pb monolayers adsorbed on Ge surfaces constitute an ideal two-dimensional metal. Since the mutual solid solubilities are negligible over all temperatures for which lead does not desorb, a well-defined interface is formed, without complications due to alloying or dissolution in the bulk.…”

“…From reflection high-energy electron-diffraction ͑RHEED͒, x-ray scattering, and low-energy electrondiffraction ͑LEED͒ measurements, a structural model has been proposed with a saturation coverage of 4 3 ML ͑four atoms per unit cell͒. [7][8][9][14][15][16]26 This structure is essentially a 1% compressed close-packed Pb͑111͒ layer rotated by 30°w ith respect to the underlying Ge lattice.…”

Energy of the Pb{111}‖Al{111} interface

“…This crystal was placed in as much as 50 K below the bulk melting temperature. [14][15][16][17][18][19][20] an ultrahigh vacuum chamber equipped with a sputtering It is generally acknowledged that the presence of surface gun, an Auger spectrometer, and a Pb physical vapor deposipremelting is the reason why superheating is rarely seen in tion source. The Al single crystal was cleaned using repeated metals with free surfaces.…”