Development of Scanning Tunneling Microscope Operated under High Pressure Environments

The aim of this research project is to develop a scanning tunneling microscope(STM)capable to be easily handled under super high pressure environments and to study on interfacial phase transition through STM observation of molecular alignments of liquid crystal monolayers as well as their alignment structures。The results obtained are following.(1)The improvement of a high pressure STM and the realization of its operation under600 MPa were done.(2)The molecular alignments of C I D260个D2 and C I D270个D2were directly observed with STM under 350 MPa。Although phase transitions(PHs)of bulk phase of C I D 260个D 2 and C I D 270个D 2 were observed near 350 MPa based on previous studies，PHs of the monolayers were not observed at least by 400 MPa(3)The systematic observations were carried out for the molecular alignments of homologous series in monolayers of n-cyanobiphenyle(NCB)and n-alkyloxy-cyanobiphenle(NCB)liquid crystals on higly horyed horyed phenyle(NCB)More isulfide(MoS2)substrates using scanning tunneling microscope(STM)，as well as two-phase mixtures of n-CB.In nCB with n=odd number，only the single row alignments in the monolayer was observed。The monolayer alignments of nCB with n=even on the other hand showed double row characteristics.For nOCB these tendencies were opposite，that is，single tow for n=even and double row for n=odd。Thus all the observed aspects clearly indicated the odd-even effect of carbon numbers in alkyl chains.The origin of the even-odd effect is due to the orientation of prana-zigzag planes of alkyl-chains in nCB and nOCB，which is perpendicular to the substrate plane.The odd-even effect is therefore strongly related to the strength of interactions with substrates through such an orientation。In nCB and nOCB for n=odd，the end carbon atom of an alkyl-chain must be free from and rigid substrates respectively。That is the interaction for n=even in nCB(NOCB)is stronger(Weaker)than that for n=odd。This difference leads to basically two different alignments，I.e.，the single and double rows.The proposed model has been verified by computer simulation Less

The aim of this research project is to develop a scanning tunneling microscope (STM) capable to be easily handled under super high pressure environments and to study on interfacial phase transition through STM observation of molecular alignments of liquid crystal monolayers as well as their alignment structures. The results obtained are following.(1) The improvement of a high pressure STM and the realization of its operation under 600 MPa were done.(2) The molecular alignments of CィイD260ィエD2 and CィイD270ィエD2 were directly observed with STM under 350MPa. Although phase transitions (PHs) of bulk phase of CィイD260ィエD2 and CィイD270ィエD2 were observed near 350MPa based on previous studies, PHs of the monolayers were not observed at least by 400MPa(3) The systematic observations were carried out for the molecular alignments of homologous series in monolayers of n-cyanobiphenyle (nCB) and n-alkyloxy-cyanobiphenle (nOCB) liquid crystals on highly oriented pyrolytic graphite (HOPG) and molybdenum d … More isulfide (MoSィイD22ィエD2) substrates using scanning tunneling microscope (STM), as well as two-phase mixtures of n-CB. In nCB with n=odd number, only the single row alignments in the monolayer was observed. The monolayer alignments of nCB with n=even on the other hand showed double row characteristics. For nOCB these tendencies were opposite, that is, single tow for n=even and double row for n=odd. Thus all the observed aspects clearly indicated the odd-even effect of carbon numbers in alkyl chains. The origin of the even-odd effect is due to the orientation of prana-zigzag planes of alkyl-chains in nCB and nOCB, which is perpendicular to the substrate plane. The odd-even effect is therefore strongly related to the strength of interactions with substrates through such an orientation. In nCB and nOCB for n=odd, the end carbon atom of an alkyl-chain must be free from and rigid substrates respectively. That is the interaction for n=even in nCB (nOCB) is stronger (weaker) than that for n=odd. This difference leads to basically two different alignments, I.e., the single and double rows. The proposed model has been verified by computer simulation Less