The physical properties of surface modified indium-tin oxide (ITO) and SnO 2(110) with an adsorbed aliphatic chain monolayer were studied by soft-landing experiments coupled with infrared (IR) spectroscopy, temperature programmed desorption (TPD) spectroscopy, and scanning probe microscopy. The IR spectra showed that the aliphatic chains of palmitic acid on both the metal oxide surfaces form a crystalline-phase monolayer with an all-trans conformation at room temperature. Gas-phase synthesized Cr(benzene) 2 cations deposited with a hyperthermal energy (20 eV) were used to probe the surface morphology. The IR spectrum after deposition showed that the cations soft-landed after being neutralized and oriented to cant the molecular axes far from the surface normal direction through penetration into the monolayer matrix. The TPD spectrum showed that the desorption activation energy of Cr(benzene) 2 from an aliphatic monolayer on ITO is much lower than that from the aliphatic monolayer on SnO 2 or a self-assembled monolayer of alkanethiol on Au(111). The lower thermal stability of Cr(benzene) 2 on the aliphatic monolayer on ITO can be ascribed to considerable surface roughness of the ITO itself, which can be characterized by scanning probe microscopy.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films