Low-energy vibrational excitation cross section of multilayers of CO molecules on graphite using electron scattering

Abstract

This paper presents a low-energy study of the vibrational excitation cross section of 50 layers of CO molecules on graphite at 23 K using the electron energy loss spectroscopy technique. The vibrational excitation cross section or the excitation curve is presented for two different scattering angles. The results show an energy dependence of the vibrational excitation cross section, at both angles, which indicates the formation of negative ion resonance in this adsorbed phase of CO on graphite. The data show an oscillatory structure in the region between 0.5 and 3 eV that is associated with the excitation of the ²Π state.

Keywords:

• ultracold molecules
• Rydberg

Acknowledgements

This work was supported by a studentship from Cambridge Overseas Trust, the Karim Rida Said Foundation and Christ's College. I wish to thank Cavendish Laboratory workshop for help and support during the time of the experiment and Mr. Peter Flaxman for constantly providing the liquid helium. Without the help and continuous support of Dr. W. Allison I would never have been able to conduct a single electron scattering experiment. I am greatly indebted and grateful to him for all the help provided.