Theoretical Study on Chemical Structures and Stability of Molecules in Metallic Junctions

• Main Author: Hu, Wei
• Format: Doctoral Thesis
• Language: English
• Published: KTH, Teoretisk kemi och biologi 2016
• Subjects: SERS; IETS; Interface; Chemical Stability
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185947; http://nbn-resolving.de/urn:isbn:978-91-7595-992-4

In this thesis, we focus on the structural identification of the interface using surface enhanced Raman spectroscopy (SERS) and inelastic electron tunnelling scattering (IETS). Two different molecular junctions, namely gold/ trans-1,2-bis (4-pyridyl) ethylene/gold junction and gold/4,4'-bipyridine/gold junctions in various conditions were studied and the corresponding configurations were determined. The enhancement in SERS was also studied by employing the time-dependent density functional theory. Furthermore, we studied some properties of the interface, such as the stability of the adsorbates and charge transfer properties of molecular junctions. The decrease in the stability of molecules was found when adsorbed on metallic surface and trapped in metallic junctions. Our studies explained several puzzles and by rational design, more stable molecular devices were obtained.