Study of the evolution in space and time of water diffusion in a leaf through a sub-terahertz portable imaging system

Among the non-destructive techniques capable of obtaining information on biological systems even in vivo, terahertz-based techniques are emerging due to their specificity to the water content, which can represent an important indicator of the presence of microorganisms and, in general, of the health status, particularly in plants. Nevertheless, the analysis of the extracted data (especially for images) and the exploitation of the potential of the technique for the study of the complex phenomena that occur in living tissues are still almost unexplored fields. In this work, the hydration status of leaves both in vivo and ex vivo was monitored continuously and non-destructively by acquiring videos in the sub-terahertz range through a portable imaging system. A model for describing the water flow in space and time in the midvein of a leaf is obtained which is suitable for the analysis of the data extracted from the portable sub-terahertz imaging system. These results show that terahertz-based technology can be used to study biological phenomena even in vivo; moreover, they pave the way for the introduction of a general method for the analysis of terahertz data based on surface fits in space and in time as well

Effect of a plasma polymerised linalyl acetate dielectric on the optical and morphological properties of an n-type organic semiconductor

Thin films of the n-type, organic semiconductor PDI-8CN2 were thermally evaporated on two different dielectric surfaces and their optical and morphological properties investigated using Variable Angle Spectroscopic Ellipsometry (VASE) and Atomic Force Microscopy (AFM), respectively. The two dielectric surfaces used were SiO2 and a plasma polymer derived from the non-synthetic monomer linalyl acetate. The characterisations were performed in order to assess the viability of plasma polymerised linalyl acetate (PLA) thin films as dielectric layers in future Organic Field-Effect Transistor (OFET) devices. These studies resulted in determination of the optical profiles (refractive index and extinction coefficient) in the UV-Vis band of PDI-8CN2 grown on SiO2 and an observation of uniaxial anisotropy in the organic semiconductor. This information is useful for the design of opto-electronic devices using PDI-8CN2 layers. Variations in morphological properties and small variations optical properties were found when the PDI-8CN2 films were grown on PLA layers, and attributed to the change in surface chemistry between dielectrics