A TPD-based determination of the graphite interlayer cohesion energy

Area of Science:

• Surface Science
• Materials Science
• Physical Chemistry

Background:

• Polycyclic Aromatic Hydrocarbons (PAHs) are crucial in various scientific fields.
• Understanding PAH interactions with surfaces like graphite is essential for materials science.
• Accurate measurement of binding energies and cohesion forces is key.

Purpose of the Study:

• To determine the binding energies of PAHs (C22Hn to C60Hn) on highly oriented pyrolytic graphite.
• To estimate the dispersive graphite interlayer cohesion energy using a refined extrapolation method.
• To evaluate the limitations of Temperature Programmed Desorption (TPD) for such measurements.

Main Methods:

• Utilized Temperature Programmed Desorption (TPD) spectroscopy.
• Employed a refined extrapolation method based on Björk et al. for cohesion energy estimation.
• Analyzed binding energies of polycyclic aromatic hydrocarbons with varying carbon numbers (22-60) on graphite.

Main Results:

• Obtained binding energies for polycyclic aromatic hydrocarbons on highly oriented pyrolytic graphite.
• Estimated the dispersive graphite interlayer cohesion energy to be 44.0 ± 3.8 meV per carbon atom.
• Identified and discussed limitations associated with the TPD-based approach.

Conclusions:

• The TPD method provides a viable route to estimate graphite interlayer cohesion.
• The determined cohesion energy offers a new data point for understanding graphite's bulk properties.
• Comparison with previous studies highlights the strengths and weaknesses of different experimental approaches.