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TPD Calculator for a Lattice Gas

This page can simulate temperature programmed desorption (TPD) spectra. It can also calculate the adsorption energy distribution from an experimental TPD spectrum at saturation coverage.
For more information and the underlying theory, see M. Schmid, G. S. Parkinson, U. Diebold, Analysis of temperature-programmed desorption via equilibrium thermodynamics, ACS Phys. Chem. Au 2 (2022).
Currently this page does not include the “magic formula”, which determines the adsorption energy from the peak temperature and peak width. When the peak temperature is given, this calculator performs a TPD simulation based on the input data. You can then check whether the peak width agrees with experiment. If it doesn't, the assumptions made in the input (sticking coefficient, soft vibration modes, dissociation for molecules like H2, single adsorption energy vs. energy distribution, etc.) need to be questioned. When doing a simulation for a single adsorption energy, this page provides some thermodynamic data required for the magic formula (gray output below the input fields).

Calculation for what 
Gas  a)  
Ramp rate β  K/s
Adsorption sites/area na 
Tpeak  K; FWHM = K
|Eads0 J/mol   b)
Adsorbate vibrations Evib  cm-1   c)
Extra entropy Sad,extra/R  d)
Initial coverage θ0 
Sticking:      (mobile precursor)
  (Langmuir-type adsorption)

Plot experimental TPD curve(s) for comparison


Export plot: T = K,    × pxl,  Line width pxl   

T, Calculated desorption rate(s)

Author: Michael Schmid, IAP/TU Wien.
This work is licensed under GNU General Public License (GPLv3) and Creative Commons Attribution-ShareAlike 4.0 (CC-BY-SA 4.0). The plot library Plotly is licensed under the MIT license.
When using and/or modifying this program for scientific work please cite our paper:
Michael Schmid, Gareth S. Parkinson, and Ulrike Diebold, Analysis of temperature-programmed desorption via equilibrium thermodynamics ACS Phys. Chem. Au (2022), doi: 10.1021/acsphyschemau.2c00031.
For offline use, the latest version of this program (updated with respect to the one in this paper) is available via the download page.
Note that exporting the plot as .png file may not work correctly in Firefox if privacy.resistFingerprinting is enabled in about:config.

surface/tpd_calculator.txt · Last modified: 2023-01-02 16:28 by Michael Schmid