Can one define the conductance of amino acids?
Linda A. Zotti (Universidad Autónoma de Madrid)
Beatrice Bednarz (Kavli institute of nanoscience Delft, Student TU Delft)
Juan Hurtado-Gallego (Universidad Autónoma de Madrid)
Damien Cabosart (TU Delft - QN/van der Zant Lab, Kavli institute of nanoscience Delft)
Gabino Rubio-Bollinger (Universidad Autónoma de Madrid)
Nicolas Agrait (Universidad Autónoma de Madrid, Campus Universitario de Cantoblanco, Madrid)
Herre S.J. van der Zant (Kavli institute of nanoscience Delft, TU Delft - QN/van der Zant Lab)
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Abstract
We studied the electron-transport properties of ten different amino acids and one dimer (di-methionine) using the mechanically controlled break-junction (MCBJ) technique. For methionine and cysteine, additional measurements were performed with the scanning tunneling microscope break-junction (STM-BJ) technique. By means of a statistical clustering technique, we identified several conductance groups for each of the molecules considered. Ab initio calculations revealed that the observed broad conductance distribution stems from the possibility of various binding geometries which can be formed during stretching combined with a multitude of possible conformational changes. The results suggest that it would be helpful to explore different experimental techniques such as recognition tunneling and conditions to help identify the nature of amino-acid-based junctions even further, for example, with the goal to establish a firm platform for their unambiguous recognition by tunneling break-junction experiments.