Title
Qualitative and quantitative analysis of complex temperature-programmed desorption data by multivariate curve resolution
Date Issued
01 October 2010
Access level
metadata only access
Resource Type
journal article
Author(s)
University of Delaware
Abstract
The substantial amount of information carried in temperature-programmed desorption (TPD) experiments is often difficult to mine due to the occurrence of competing reaction pathways that produce compounds with similar mass spectrometric features. Multivariate curve resolution (MCR) is introduced as a tool capable of overcoming this problem by mathematically detecting spectral variations and correlations between several m/z traces, which is later translated into the extraction of the cracking pattern and the desorption profile for each desorbate. Different from the elegant (though complex) methods currently available to analyze TPD data, MCR analysis is applicable even when no information regarding the specific surface reaction/desorption process or the nature of the desorbing species is available. However, when available, any information can be used as constraints that guide the outcome, increasing the accuracy of the resolution. This approach is especially valuable when the compounds desorbing are different from what would be expected based on a chemical intuition, when the cracking pattern of the model test compound is difficult or impossible to obtain (because it could be unstable or very rare), and when knowing major components desorbing from the surface could in more traditional methods actually bias the quantification of minor components. The enhanced level of understanding of thermal processes achieved through MCR analysis is demonstrated by analyzing three phenomena: i) the cryogenic desorption of vinyltrimethylsilane from silicon, an introductory system where the known multilayer and monolayer components are resolved; ii) acrolein hydrogenation on a bimetallic Pt-Ni-Pt catalyst, where a rapid identification of hydrogenated products as well as other desorbing species is achieved, and iii) the thermal reaction of Ti[N(CH3)2]4 on Si(100), where the products of surface decomposition are identified and an estimation of the surface composition after the thermal reaction is afforded. Since this work constitutes, to the best of our knowledge, the first effort to introduce multivariate analysis to TPD data, the procedures, algorithms and strategies employed are described in full detail. © 2010 Elsevier B.V. All rights reserved.
Start page
2043
End page
2054
Volume
604
Issue
21-22
Language
English
OCDE Knowledge area
Química orgánica
Subjects
Scopus EID
2-s2.0-77957158989
Source
Surface Science
ISSN of the container
00396028
Sponsor(s)
Funding text
This work was supported by the National Science Foundation ( CHE-0650123 ). Acknowledgment is also made to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this research. The authors would like to thank the valuable cooperation of Prof. J. G. Chen and Dr. M. Humbert in providing the data corresponding to acrolein hydrogenation. Dr. L. Pirolli is acknowledged for collecting the original VTMS desorption data. J. C. F. R.-R. acknowledges the valuable help of Prof. K. Booksh, Mrs. D. Chavez and Mr. B. Herbert (Department of Chemistry and Biochemistry, University of Delaware) during the initial stages of the application of MCR analysis to the TPD data and of Dr. N. Gallagher (Eigenvector Research, Inc.) during the course of the investigations reported here.
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