Microscopic Observation of Step and Terrace Diffusion of Indium Atoms on Cu(111) Surfaces

Abstract

The perturbed yy angular correlation (PAC) method has been applied to study isolate ' "In probe atoms on vicinal Cu(ll1) surfaces. The properties of the observed electricfield gradients and the annealing behaviour suggest the existence of indium as step adatoms up to 140 K, above this temperature these adatoms convert into substitutional step atoms. At 220 K the indium probes finally start to diffuse into substitutional terrace sites. Desorption and diffusion into bulk was also detected. From the thermal conversion between the different sites activation energies have been estimated.

Diffusion and incorporation of a surfactant: In on (vicinal) Cu(001)

“…7 shows that In incorporated two or three rows deep into the terrace, while the kinks of the copper step fluctuated only over a few atomic positions along the step in the same time, thereby displacing the average step position over a small fraction of an atomic spacing. This indicates that the incorporation did not take place via step fluctuations, as had already been suggested by earlier PACS experiments [9,10,16]. Instead, a vacancy-assisted incorporation mechanism is active at room temperature, as has already been discussed elsewhere [27,30].…”

“…[8][9][10][11][12][13]. Perturbed angular correlation spectroscopy (PACS) makes use of the anisotropic emission of c-rays of a set of excited probe nuclei with respect to the direction of their nuclear spin.…”

“…After it has been deposited, it forms a surface alloy and already works as a surfactant at coverages as low as a few percent of a monolayer [6]. The In/Cu(0 0 1) system has been studied extensively with the technique of perturbed angular correlation spectroscopy (PACS) [8][9][10][11][12][13]. The results from these studies indicate the indium atoms go through a sequence of four different sites on/in the Cu(0 0 1) surface in the course of the incorporation process: (1) an isolated In adatom on the Cu(0 0 1) terrace, the adatomic terrace site, (2) an isolated In atom residing at a kink, the adatomic step site, (3) an isolated In atom incorporated in the first row of a step, the substitutional step site and (4) an isolated In atom incorporated in a Cu(0 0 1) terrace, the substitutional terrace site.…”

“…Combining the STM results with the PACS data of Refs. [8][9][10][11][12][13], we construct a comprehensive picture for the entire incorporation process.…”

Step dynamics and step–step interactions on the chiral Cu(5 8 90) surface

“…Some of the experimental studies focused on the structure and stability of high-Miller-index surfaces during adsorption [5][6][7][8]; others investigated surface reconstructions [9][10][11][12][13] or surface relaxations [14]. The importance of high-Miller-index surfaces (or "vicinal" surfaces as they are frequently called) in surface science was acknowledged by introducing a special notation such that the structure of the denoted crystal planes could be recognized straight forwardly just by their notation (sometimes denoted as the "Somorjai notation") [15].…”