Molecular detection on a defective MoS$_2$ monolayer by simultaneous conductance and force simulations

Cesar Gonzalez Pascual (1, 2) , Y. J. Dappe (3)

1 FMC - Departamento de Fisica de la Materia Condensada [Madrid]
2 UGR - Universidad de Granada = University of Granada
3 GMT - Groupe Modélisation et Théorie

Based on simultaneous force and conductance simulations, a proof of concept for a potential method of molecular detection is presented. Using density functional theory calculations, a metallic tip has been approached to different small inorganic molecules such as CO, CO$_2$ , H$_2$O, NO, N$_2$ , or O$_2$. The molecules have been previously chemisorbed on a defect formed by two Mo atoms occupying a S divacancy on a MoS 2 monolayer where they are strongly bonded to the topmost substitutional molybdenum. At that site, the fixed molecules can be imaged by a conductive atomic-force-microscopy tip. Due to the differences in atomic composition and electronic configurations, each molecule yields specific conductance/force curves during the tip approach. A molecule-tip contact is established at the force minimum, followed by the formation of a characteristic plateau in the conductance in most of the cases. Focusing our attention on the position and values of such force minimum and conductance maximum, we can conclude that both characteristic properties can give a clear signature of each molecule, proposing a different method of detecting molecules adsorbed on highly reactive sites.

Domaines: Physique [physics]

Cesar Gonzalez Pascual, Y. J. Dappe. Molecular detection on a defective MoS$_2$ monolayer by simultaneous conductance and force simulations . Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2017, 95, pp.214105. ⟨10.1103/PhysRevLett.106.176101⟩. ⟨cea-01567825⟩