Cesium adsorption on TiO{sub 2}(110)

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.1844· OSTI ID:475293

Grant, A W; Campbell, C T ^[1]

---

1. Chemistry Department, Box 351700, University of Washington, Seattle, Washington 98195-1700 (United States)

The adsorption of Cs on a TiO{sub 2}(110) rutile surface was investigated at 130{endash}800K using x-ray photoelectron spectroscopy, x-ray excited Auger electron spectroscopy, temperature-programmed desorption, work-function, and band-bending measurements. Below room temperature, the Cs displays a Stranski-Krastanov growth mode, with the completion of a uniform monolayer (ML) containing (6{plus_minus}2){times}10{sup 14} Cs adatoms per cm{sup 2}, followed by the growth of three-dimensional clusters of Cs that cover only a small fraction of the surface. The Cs in the first {approximately} (1/2) ML is very cationic, donating electron density to the TiO{sub 2}. Most of this charge is localized near the topmost atomic layers, with Ti{sup 4+} ions being reduced to Ti{sup 3+}. This gives rise to a local dipole moment of the adsorbate-substrate complex of {approximately}6D at {approximately}0.1 ML. However, a small part of the charge transferred to the substrate also goes much deeper into the solid, giving rise to downward band bending of {approximately}0.2{endash}0.3 eV. This band bending nearly saturates at {approximately}0.05 ML. The local dipole moment of the alkali-metal{endash}substrate complex decreases smoothly with coverage in the first ML, due to dipole-dipole repulsions and their consequent mutual depolarization, similar to transition-metal surfaces. This gives rise to a rapid and smooth decrease in the heat of adsorption with coverage from {gt}208kJ/mol down to {approximately}78kJ/mol. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 475293
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 3 Vol. 55; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
AUGER EFFECT
CESIUM
CRYSTALS
ELECTRON SPECTRA
ELECTRON SPECTROSCOPY
GROWTH
MONOCRYSTALS
RUTILE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TITANIUM OXIDES
WORK FUNCTIONS
X-RAY SPECTRA