Seminars Archive

Controlling the structure and functions of physisorbed nanosystems

Abstract
Two examples on how to control the structure and function of organic/inorganic nanosystems will be presented. The first part of the talk will deal with deposition of small-molecule organic semiconductors on vicinal sapphire surfaces. We will demonstrate that one can grow low-dimensional organic structures on sapphire, provided the substrate surface is characterized by atomically flat terraces and well-defined step edges. We will address the stability of these structures and suggest possible experiments to measure their electrical and optical properties. In the second part of the talk we will show how the optical properties of the organic dye methylene blue can be modified by adsorbing the molecule onto the surface of protonated titanate nanowires. We will demonstrate that, due to a unique coupling between the molecules and the nanowire surface, this nanocomposite system responds to changes in the relative humidity by changing its color. By analyzing Raman, fluorescence and transmission spectra we will clarify the mechanism behind the process. We will show that this humidity dependent metachromasy can be exploited in an optical fiber based humidity sensor. We will discuss the possible application of the sensor as a breathing monitor.