Surveying molecular vibrations during the formation of metal-molecule nanocontacts.
Molecular junctions have been characterized to determine the influence of the metal contact formation in the electron transport process through a single molecule. With inelastic electron tunneling spectroscopy and first-principles calculations, the vibration modes of a carbon monoxide molecule have been surveyed as a function of the distance from a copper electrode with unprecedented accuracy. We observe a continuous but nonlinear blue shift of the frustrated rotation mode in tunneling with decreasing distance followed by an abrupt softening upon contact formation. This indicates that the presence of the metal electrode sensibly alters the structural and conductive properties of the junction even without the formation of a strong chemical bond.
Vitali
Lucia
L
Max-Planck-Institute fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany. lucia_vitali@ehu.es
Ohmann
Robin
R
Kern
Klaus
K
Garcia-Lekue
Aran
A
Frederiksen
Thomas
T
Sanchez-Portal
Daniel
D
Arnau
Andres
A
D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry; D004553:Electric Conductivity; D004566:Electrodes; D053768:Metal Nanoparticles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D010100:Oxygen / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods; D013499:Surface Properties; D014732:Vibration
D008670:Metals; D002248:Carbon Monoxide; D010100:Oxygen