Local fluctuations during catalytic CO oxidation on Pt

A field emission study

authored by: Yu Suchorski, J. Beben, R. Imbihl
Abstract: Field electron microscopy (FEM) is employed to monitor local brightness fluctuations that occur during catalytic CO oxidation on a Pt field emitter tip and that are caused by local variations in the adsorbate coverages. The reaction is studied in the bistability range at T = 310 K with fixed p_o2 = 4.0 x 10^-4 Torr and p_CO = 3.0 x 10^-7 Torr. The measurements are conducted on the apex plane of a [100]-oriented Pt tip. Local time series are obtained by digitization of the video-recorded FEM image (40 ms time resolution) and integration of the intensity in windows of 100 x 100 Å and 20 x 100 Å size. From the measured time series, the autocorrelation and cross-correlation functions were determined. Fluctuations on the reactive (oxygen covered) and on the inactive (CO covered) branch of the reaction exhibit quite substantial differences. On the reactive branch, spatial correlations extend over much longer distances (several hundred angstroms) than on the unreactive branch, and time correlations decay much more slowly. These differences are discussed on the basis of the Langmuir-Hinshelwood mechanism for catalytic CO oxidation. The fluctuations on the unreactive branch apparently originate from CO diffusion alone.
Organisation(s): Institute of Physical Chemistry and Electrochemistry
External Organisation(s): University of Wroclaw
Type: Article
Journal: Surface science
Volume: 405
Pages: L477-L483
ISSN: 0039-6028
Publication date: 12.05.1998
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry

BibTeX

@article{d14815ea179d4683932a49fe6f1c793a,
title = "Local fluctuations during catalytic CO oxidation on Pt: A field emission study",
abstract = "Field electron microscopy (FEM) is employed to monitor local brightness fluctuations that occur during catalytic CO oxidation on a Pt field emitter tip and that are caused by local variations in the adsorbate coverages. The reaction is studied in the bistability range at T = 310 K with fixed po2 = 4.0 x 10-4 Torr and pCO = 3.0 x 10-7 Torr. The measurements are conducted on the apex plane of a [100]-oriented Pt tip. Local time series are obtained by digitization of the video-recorded FEM image (40 ms time resolution) and integration of the intensity in windows of 100 x 100 {\AA} and 20 x 100 {\AA} size. From the measured time series, the autocorrelation and cross-correlation functions were determined. Fluctuations on the reactive (oxygen covered) and on the inactive (CO covered) branch of the reaction exhibit quite substantial differences. On the reactive branch, spatial correlations extend over much longer distances (several hundred angstroms) than on the unreactive branch, and time correlations decay much more slowly. These differences are discussed on the basis of the Langmuir-Hinshelwood mechanism for catalytic CO oxidation. The fluctuations on the unreactive branch apparently originate from CO diffusion alone.",
keywords = "Carbon monoxide, Field emission, Oxidation, Oxygen, Platinum, Surface chemical reaction",
author = "Yu Suchorski and J. Beben and R. Imbihl",
note = "Funding Information: Financial support from the Deutsche For-schungsgemeinschaft is gratefully acknowledged.",
year = "1998",
month = may,
day = "12",
language = "English",
volume = "405",
pages = "L477--L483",
journal = "Surface science",
issn = "0039-6028",
publisher = "Elsevier",
number = "1",
}