Marchenko O. Scanning tunneling microscopy of organic molecules at the liquid-solid interface.

The thesis is devoted to experimental and theoretical investigations of structures and properties of self-assembled superthin (sub- and monolayer) organic films (OF) deposited from solution on atomically flat surfaces: reconstructed Au(111) facet and basal plane of highly oriented pyrolitic graphite (0001). The structural investigations of OF have been performed by in-situ scanning tunneling microscope (STM) adapted to the liquid environment. The n-tetradecane, C14H30, is used in STM experiments for the first time as multifunctional liquid which creates quasi-vacuum conditions for the substrate and simultaneously serves as tunnelling medium and solvent for deposition. The molecularly resolved STM-images are obtained for monolayers of long-chain compounds (n-alkanes, CnH2n+2, n=10-50, silanes, thiols), discotic liquid-crystals (triphenylenes, hexa-peri-hexabenzocoronenes), fullerenes (C60, C70). It has been found that the 23 3 reconstruction is the necessary condition for self-organization of investigated molecules on Au(111) surface. It is revealed that the structures and properties (stability, melting behavior, tribological) of n-alkane films on Au(111) depend on the molecule length in a non-monotonic manner. The one-dimensional model based on the misfit between periodicity of alkyl chain and Au(111) surface along 110 direction is developed for explanation of adsorption anomalies in n-alkane Au(111) system. The influence of chemical modification on structural organization of triphenylene-, hexabenzocoronene- and silane- derivatives was systematically studied. The examples of single molecule manipulations, nanoscale controlled phase transitions and film growth, tip-induced formation of artificial nanostructures (nanofabrication) are presented. The observed self-organized nanostructures are discussed in terms of adsorption and lateral interactions.