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Title: Adsorption and reactivity of halogenated hydrocarbons on metal and semiconductor surfaces
Author: Panosetti, Chiara
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2013
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We investigated the adsorption and reactivity of substituted hydrocarbons on Si and Cu surfaces using Grimme’s vdW–corrected DFT, CI–NEB and STM simulations. Halogenated hydrocarbons on surfaces are systems of particular interest. These molecules adsorb and self–assembly at surfaces and many experimental works show that, if one provides energy to the complex, in the form of heat, light, or electrons dropped with an STM tip, they easily react resulting in single, or patterns of, chemisorbed atoms at specific and controllable sites. For instance, 1–chloropentane forms asymmetric (A) and symmetric (S) pairs on Si(001)–2×1. The rate of thermal reaction of A is greater than S in chlorinating room-temperature silicon. The energy threshold for electron–induced reaction is also different. We have used DFT and NEB tools to explain the features of this system and we simulated STM images in agreement with the experiments. On the other hand, diiodobenzenes physisorbed on Cu(110) can act as molecular calipers. We have computationally modelled the adsorption of 1,3-diiodobenzene (m–DIB) on Cu(110) and simulated STM images for the four most stable configurations using the Tersoff–Hamann approach at different bias voltages. We find that all the adsorption orientations have comparable energy and we discuss the relative probabilities of experimental observation as well as the structural details. We have furthermore compared the electronic ground–state reactivity of 1,3– and 1,4–diiodobenzene in order to show that the different symmetry of the initial adsorbed state greatly affects reactivity. Since the studied systems provide a means to surface functionalization via site–specific imprinting of single atoms, we also propose a model for Cu nanoclusters on Cu(110) supported by one or two chemisorbed S (or Cl) atoms.
Supervisor: Hofer, Werner A.; Darling, George Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: QD Chemistry