1. |
- Laegsgaard, E, et al.
(author)
-
A high-pressure scanning tunneling microscope
- 2001
-
In: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 72:9, s. 3537-3542
-
Journal article (peer-reviewed)abstract
- We present the design and performance of a high-pressure scanning tunneling microscope (HP-STM), which allows atom-resolved imaging of metal surfaces at pressures ranging from ultrahigh vacuum (UHV) to atmospheric pressures (1 x 10(-10)-1000 mbar) on a routine basis. The HP-STM is integrated in a gold-plated high-pressure cell with a volume of only similar to0.5 l, which is attached directly to an UHV preparation/analysis chamber. The latter facilitates quick sample transfer between the UHV chamber and the high-pressure cell, and allows for in situ chemical and structural analysis by a number of analytical UHV techniques incorporated in the UHV chamber. Reactant gases are admitted to the high-pressure cell via a dedicated gas handling system, which includes several stages of gas purification. The use of ultrapure gasses is essential when working at high pressures in order to achieve well-defined experimental conditions. The latter is demonstrated in the case of H/Cu(110) at atmospheric H-2 pressures where impurity-related structures were observed. (C) 2001 American Institute of Physics.
|
|
2. |
- Pedersen, M O, et al.
(author)
-
Diffusion of N adatoms on the Fe(100) surface
- 2000
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 84:21, s. 4898-4901
-
Journal article (peer-reviewed)abstract
- The diffusion of individual N adatoms on Fe(100) has been studied using scanning tunneling microscopy and ab initio density functional theory (DFT) calculations. The measured diffusion barrier for isolated N adatoms is E-d = (0.92 +/- 0.04) eV, with a prefactor of nu(0) = 4.3 x 10(12) s(-1), which is in quantitative agreement with the DFT calculations. Thr; diffusion is strongly coupled to lattice distortions. and. as a consequence, the presence of other N adatoms introduces an anisotropy in the diffusion. Based on experimentally determined values of the diffusion barriers and adsorbate-adsorbate: interactions, the potential energy surface experienced by a N adatom is determined.
|
|
3. |
- Österlund, Lars, 1967-, et al.
(author)
-
Bridging the pressure gap in surface science at the atomic level : H/Cu(110)
- 2001
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 86:3, s. 460-463
-
Journal article (peer-reviewed)abstract
- The structural response of the Cu(110) surface to H-2 gas pressures ranging from 10(-13) to 1 bar is studied using a novel high-pressure scanning tunneling microscope (HP-STM). We find that at H-2 pressures larger than 2 mbar the Cu(110) surface reconstructs into the (1 X 2) "missing-row" structure. From a quantitative analysis of the pressure dependence of the surface reconstruction, we conclude that Cu(110) responds identically to hydrogen at ultrahigh vacuum conditions and at atmospheric pressures. From the HP-STM data, we extract refined values for the adsorption and desorption rate constants.
|
|