The Surface Structure of Liquid Metals and Alloys

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The Surface Structure of Liquid Metals and Alloys
Current associates are underlined
Non-Harvard Collaborators Ben Ocko, Elaine
DiMasi, Olaf Magnussen Physics Dept. Brookhaven
National Laboratory Moshe Deutsch Bar Ilan
University, Israel Binhua Lin, Mati Meron, Tim
Graber, Jeff Gerbhardt, Advanced Photon
Source Harvard Students/Postdocs Alexei
Grigoriev, Patrick Huber, E.H. Kawamoto, Holger
Tostmann, Mike Regan, Oleg Shpyrko.
Oleg Shpyrko
Support DE-FG02-88-ER45379/NSF- DMR-0124936
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Liquid Surfaces Metals/Non-Metals Are Different
D'Evelyn . Rice, J. Chem. Phys., 1983. 78 p.
5225.
For Metals Particle-Particle Interactions Change
Across The Surface
This influences the structure of the surface!
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Non-Metal Liquids
Predictions of Monte Carlo Calculations Average
Density ltr(z)gt vs Distance From Surface(z)
Liquid/Vapor Surface Structure Factor F(Qz)
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X-ray Reflectivity R(Qz) F(Qz)
Quantitative Measure of F(Qz)!
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Thermal Effects on Reflectivity
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Liquid vs Solid Surfaces
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Measure of Structure Factor Requires Thermal
Effects be Removed
Large (T/g)Qz2 No specular peak if h2!
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To Understand Thermal EffectsDiffuse Scattering
From Liquid Surface
Qx(2p/l)cos a-cos b
Qz(2p/l)sin asin b
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Demonstration of Thermal Removed Liquid Gallium
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Issue 1 What other metals can be studied?
h (i.e. T/g) must be small
P T low enough for UHV(Hg, K, Na are special)
Element Tm (K) ? Tm/g P_melt(mm) Ga 302.93 718 0.4
2 Hg 234.28 498 0.47 1.2E-06 Sn 505.118 560 0.90
In 429.32 556 0.77 K 336.8 388 0.87 1.0E-6 Zn 6
92.73 782 0.89 2.2E-01 Al 933.52 914 1.02 Cu 1356
.6 1303 1.04 9.7E-04 Cd 594.1 570 1.04 1.1E-01 Bi
544.5 378 1.44 Li (Chemistry) 453.69 398 1.14 Au
1337.58 1169 1.14 1.6E-05 Tl 576.7 464 1.24 Pb 6
00.64 458 1.31
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Measurement of Potassium
Good Oxides Dissolve in Bulk Liquid?Clean
Surface Bad Low g ? h at layering peak is
large, R(Qz) too small
Data ? Layering in K is same as Ga, In.
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Anomalous Layering of Liquid Sn Surface
Bump ? Surface Density Is Higher Than Bulk!
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Is there experimental evidence that dielectric
liquids are not layered?
Water g73 dynes/cm K g?100 dynes/cm
Water does not show indication of surface
layering!
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If we cant study other pure metals, what can we
do?
AlloysSurface Chemistry of Liquid Metals
(oxidation)
Surface Heavier Bi rich liquid Bulk lighter Ga
rich liquid!
Short Range Wetting
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Keep Looking i.e. Alloys for Electronics
Example AuSi
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Summary
1- To Measure Liquid Surface Structure Factor
F(Qz)Effects of Capillary Waves.
2- F(Qz) of Free Surface of Liquid Metals
Exhibits Atomic Layering!
3- Water does Not! What about other non-metallic
liquids.
4- Surfaces of Liquid Alloys Interesting Physics
Sn Anomalous Surface GaBi Short Range
Wetting AuSi Enormously Intense
Future