Method for direct deconvolution of heat signals in transient adsorption calorimetry

• Published in: Surface science Vol. 633; no. C; pp. 17 - 23
• Main Authors: Wolcott, Christopher A., Campbell, Charles T.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-03-2015; Elsevier
• Subjects: Adsorption; Calorimetry; Deposition; Enthalpy; Fourier transforms; Iodides; Molecular beams; Response functions; SCAC; Single crystal adsorption calorimetry; Surface chemistry; Transient adsorption microcalorimetry; Single crystal adsorption calorimetry; SCAC; Transient adsorption microcalorimetry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2014.11.005

A method of heat signal analysis is presented for transient adsorption calorimetries including single crystal adsorption calorimetry (SCAC) which uses fast Fourier transforms (FFT) to determine the instrument response function and deconvolute the heat-versus-time signals. The method utilizes a heat signal generated by a laser pulse of known power-versus-time to extract the instrument response function for the calorimeter. The instrument response function is then used to extract the heat power signal from a molecular beam heat pulse of unknown intensity. This method allows for the extraction of the total heat deposited by the molecular beam pulse without any kinetic modeling even in the event of complex reaction dynamics. This method is compared to previous methods used to analyze SCAC data using example data from the two-step dissociative adsorption of methyl iodide on Pt(111). It is found to be equally accurate for extracting total heats and simpler to perform than the previous methods.
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•A method of heat signal analysis for transient adsorption calorimetries·•Utilizes FFT to deconvolute measured signal to give heat vs time·•Particularly useful for single crystal adsorption calorimetry (SCAC)·•Easily applied to systems with complex adsorption dynamics without kinetic modeling·•Applicability demonstrated, and advances over other methods discussed·