Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of $\mathrm{O}/\mathrm{Ag}(110)$

Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of $O / Ag (110)$

Jagriti Pal, Takat B. Rawal, Marco Smerieri, Sampyo Hong, Matti Alatalo, Letizia Savio, Luca Vattuone, Talat S. Rahman, and Mario Rocca

Phys. Rev. Lett. 118, 226101 – Published 1 June 2017

Abstract

The reconstruction and modification of metal surfaces upon $O_{2}$ adsorption plays an important role in oxidation processes and in gauging their catalytic activity. Here, we show by employing scanning tunneling microscopy and the ab initio density functional theory that Ag atoms are extracted from pristine (110) terraces upon $O_{2}$ dissociation, resulting in vacancies and in Ag-O complexes. The substrate roughening generates undercoordinated atoms and opens pathways to the Ag subsurface layer. With increasing O coverage, multiple vacancies give rise to remarkable structures. The mechanism is expected to be very general depending on the delicate interplay of energy and entropy, so that it may be active for other materials at different temperatures.

Received 18 November 2015

DOI:https://doi.org/10.1103/PhysRevLett.118.226101

Physics Subject Headings (PhySH)

Adsorption Surface & interfacial phenomena

Density functional theory Scanning tunneling microscopy

Condensed Matter, Materials & Applied PhysicsInterdisciplinary Physics

Authors & Affiliations

Jagriti Pal^1,2, Takat B. Rawal³, Marco Smerieri¹, Sampyo Hong⁴, Matti Alatalo⁵, Letizia Savio¹, Luca Vattuone^1,2, Talat S. Rahman³, and Mario Rocca^1,2

¹IMEM-CNR, UOS Genova, Via Dodecaneso 33, 16146 Genova, Italy
²Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy
³Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
⁴Division of Physical Sciences, Brewton-Parker College, Mount Vernon, Georgia 30445, USA
⁵Center of Molecular Materials, Faculty of Science, P.O. Box 8000, FI-90400 University of Oulu, Finland

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 118, Iss. 22 — 2 June 2017

Reuse & Permissions

Access Options

Article Available via CHORUS

Download Accepted Manuscript

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) STM image ( $250 Å \times 250 Å$ ) recorded after an exposure of 19 L of $O_{2}$ on Ag(110) at 175 K by backfilling. (b)–(d) Images of the area delimited by the rectangle in (a). Size, $120 Å \times 82 Å$ . The sequence shows the effect of vertical manipulation on the gray lines: Voltage pulses (at the yellow dots) generate two sombreros (S) and the corresponding shortening of the structure by two lattice spacings (STM images were recorded at 6 K, $V = 70 mV$ ). (e) Line profiles of BD and G along $[1 \bar{1} 0]$ [dotted line in (b)] recorded at different stages of the manipulation process. (f) Apparent depth vs bias voltage for BD corresponding to SV or DV. For SV, a comparison with simulated STM images is shown. Inset enlargement of a BD with line scans used to determine the depth.
Reuse & Permissions
Figure 2
(a)–(c) DFT-optimized geometries and (d)–(f) simulated STM images (at 70 mV) of (a),(d) O in LB (S), (b),(e) Ag vacancy (BD), and (c),(f) O atoms in threefold hollows, forming a zigzag chain on Ag(110) (G). (g)–(i) Comparison of theoretical (red trace) and experimental (black trace) depth profiles for $V = 70 mV$ . They are obtained from line scans, along $[1 \bar{1} 0]$ for (d) and (e) and along [001] for (f). To allow a comparison with the experiment, the calculated profiles were convoluted with a suitable function simulating the tip. A small dependence of the depth profile on the bias voltage is observed in the experimental data, in agreement with Fig. 1. Here and in the following, Ag atoms in the first, second, and third layers and O atoms are represented by gray, green, purple, and red balls, respectively.
Reuse & Permissions
Figure 3
Schematic representation for the formation of a single Ag vacancy and added O-Ag-O unit on Ag(110): (a) pristine surface; (b) the dissociated O atoms participate to form an O-Ag-O complex, resulting in a weakening of Ag-Ag bonds in the substrate; (c) Ag vacancy (yellow dotted line); (d) O-stabilized Ag adatom (blue dotted line); (e) diffusion of O-Ag-O complex and Ag atom in “concerted” motion; and (f) diffusion of the vacancy away from the added O-Ag-O complex.
Reuse & Permissions
Figure 4
(a),(b) STM images of $O / Ag$ (110) after dosing $O_{2}$ at 0.4 eV kinetic energy by SMB, at $T = 165 K$ (a) and $T = 185 K$ (b). The estimated coverage is 0.06 ML. Image size $450 Å \times 450 Å$ , $V = 70 mV$ , $I = 1.0 nA$ . (c) Enlargement of a butterfly structure (image size $34 Å \times 33 Å$ , $V = 70 mV$ ). (d),(e) DFT-optimized geometry and simulated STM image of the butterfly unit. See Fig. S10 in Supplemental Material [33] for the atomic positions.
Reuse & Permissions

Physical Review Letters

Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of O/Ag(110)

Jagriti Pal, Takat B. Rawal, Marco Smerieri, Sampyo Hong, Matti Alatalo, Letizia Savio, Luca Vattuone, Talat S. Rahman, and Mario Rocca

Phys. Rev. Lett. 118, 226101 – Published 1 June 2017

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

Supplemental Material (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of $O / Ag (110)$