Spectroscopic Ivestigation of Azobenzene based self-assembled monolayer on Gold, Sio2 and on water
This study was concerned with the investigation of photo-induced molecular switching processes of azobenzene based self-assembled monolayers (SAMs) on surfaces. The rational design of such surfaces, which often hold the potential for practical application, require a thorough understanding of the factors that control surface assembly into highly ordered architectures as well as photoswitching efficiency. The latter is often limited by steric hindrance, i.e., the lack of free volume in the molecular monolayer. This work further aimed at a demonstration of the capability of Sum Frequency Generation spectroscopy (SFG) to investigate diverse functionalized surfaces including reflective gold and transparent quartz substrates as well as monolayers at water-air interfaces. SFG analysis of Azobenzene (AB) on gold as well as on quartz and Azobenzenecholesterol/ Dipalmitoylphosphatidylcholine (AzoChol/ DPPC) on water was used to confirm the formation of self-assembled monolayers (SAMs) on the substrate, to depict the morphology of these SAMs and to check their photoisomerizing ability. Characteristic spectra confirmed the adsorption of molecules on the surfaces with vibrational signatures of different CH units.