Temperature programmed desorption: A statistical rate theory approach

Abstract

Articles you may be interested inDesign and construction of a semiautomatic temperature programmed desorption apparatus for ultrahigh vacuum J. Vac. Sci. Technol. A 23, 215 (2005); 10.1116/1.1818133Microsystem with integrated capillary leak to mass spectrometer for high sensitivity temperature programmed desorption Rev. Sci. Instrum. 75, 3345 (2004); 10.1063/1.1791851 Quantification of lateral repulsion between coadsorbed CO and N on Rh(100) using temperature-programmed desorption, low-energy electron diffraction, and Monte Carlo simulations Development of a temperature-programed electron-stimulated desorption ion angular distribution/time-of-flight system for real-time observation of surface processes and its application to adsorbed layers on Ru(001) Rev. Sci. Instrum. 69, 3666 (1998); 10.1063/1.1149156Temperature-programmed desorption study of the etching of Ni(110) with 2,4-pentanedione J.The equation traditionally used to interpret temperature programmed desorption ͑TPD͒ spectra, the Polanyi-Wigner equation, does not contain explicitly the coverage and temperature dependence necessary to predict TPD spectra in several important systems including CO-Ni͑111͒. Herein, the statistical rate theory ͑SRT͒ approach is used to formulate equations for temperature programmed desorption which are then used to examine TPD spectra reported in the literature for CO-Ni͑111͒. The molecular and material properties for the CO-Ni͑111͒ system have been previously established. One experimental spectrum has been chosen to determine the apparatus constants. The material properties and the apparatus constants are then used in the SRT equations to predict the eight additional TPD spectra for different initial coverages. A critical comparison can then be made between the theory and these eight experimental spectra, since no fitting constants were used in these eight cases. The results show that there is clearly qualitative agreement. The SRT equations are then used along with the heat of adsorption to derive an equation for the pre-exponential factor appearing in the Polanyi-Wigner equation. A prediction is made for the pre-exponential factor that is in agreement with that found empirically. The agreement found between the SRT predictions and the measured spectra indicates that all of the coverage and temperature dependence necessary to predict TPD spectra is given explicitly by the SRT approach. Hence, the experimental support for the SRT approach is enhanced. The SRT equations are then used to predict CO-Ni͑111͒ spectra that would occur if the heating rate were varied.

Liquid-Vapour Phase Change Rates and Interfacial Entropy Production

“…Since in the thermal desorption study, a number of experiments were performed in which only the initial surface concentration of CO was changed before the heating process was begun, the apparatus constants that were not given could be determined from one experiment, and then the pressure spectra of the other experiments could be predicted. The comparison between the measurements and the predictions give strong support to the SRT expression for adsorption kinetics [11,30].…”

“…However, the expression for the chemical potential that can: 1) successfully be used to calculate the equilibrium adsorption isotherms and to predict the coverage dependence of the heat of adsorption [29], and 2) used with SRT to predict the thermal desorption spectra of CO-Ni(111) [11] indicates that transition state theory is internally inconsistent [7].…”

“…The approach has been examined in a number of nonequilibrium circumstances, including unsteady evaporation [2], gas adsorption kinetics on homogeneous and heterogeneous surfaces [7±14], surface diffusion [15], membrane transport [16], electron transfer reactions [17], crystal dissolution [18] and gas absorption by liquids [19±21]. In each case, the SRT procedure received support from the comparison with experimental measurements, but it received particularly strong support from the comparison with measurements of the predicted phase change rate of water [1±4], thermal desorption of CO from Ni(111) [11] and gas absorption by liquids [19±21]. In these latter cases, predictions could be made of the kinetics in which there were no ®tting parameters, and the results compared with measurements.…”

Splitting methods for relaxation two-phase flow models

“…The probability of each event is calculated using a first-order perturbation analysis of the Schrödinger equation, together with the Boltzmann definition of entropy. Since its introduction by Ward et al (1982), SRT has been used to model a number of different transport processes, including crystal growth (Dejmek & Ward, 1998), solution/solid adsorption (Azizian et al, 2008;Rudzinski & Plazinski, 2006), gas/solid adsorption (Elliott & Ward, 1997a;, temperature programmed desorption (Elliott & Ward, 1997b), ion permeation across lipid membranes (Bordi et al, 2000), chemical reactions (Harding et al, 2000), and evaporation and condensation (Ward & Fang, 1999;Kapoor & Elliott, 2008;Ward & Stanga, 2001). Lund and Aursand (2012) developed an explicit expression for the phase transfer source term Γ in Eqs.…”

A Statistical Rate Theory of Interface Concentration during Solution ZeoliteCrystal Growth

“…We use a theoretical approach (statistical rate theory) to obtain the expression for the rate of solute transport across the boundary layer in terms of the concentration at the interface. The advantage of this approach is that once the model has been established, it could be incorporated into the kinetics equations and used to predict the crystal growth rate [15][16][17].…”