Registration Number
0212U002469,
0110U003481
, R & D reports
Title
Structural phase transitions in chemisorbed layers: experiment and theory at the atomic level.
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Head
Braun Oleg Mikhailovich,
Registration Date
01-03-2012
Organization
Institute of physics NASU
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The goal of the research was the investigation of collective interaction of particles adsorbed on a solid state surface and the role of this interaction in structural states of two-dimensional systems. The methods of theoretical investigation included the method of the electron density functional and computer modelling by the Monte-Carlo (MC) and Molecular Dynamics (MD) methods. In close collaboration with the Institute of General Physics of the Russian Academy of Sciences, a complex theoretical-experimental investigation of structures and phase transitions in Cl monolayers on the Ag(111) surface has been done, and the following new results were obtained: (1) the adsorption sites of Cl adatoms on the Ag(111) surface were found; (2) the energy of interaction between Cl adatoms on the Ag(111) surface was calculated, the activation energy of diffusion was found, and it was showed that it leads to lowering of adatom mobility which is essential at formation of ordered structures; (3) the formation of chain structures of Cl adatoms was investigated by the MC method, and it was shown that the chain structures appear due to indirect interaction between the Cl adatoms; the sequence of Cl structures on the Ag(111) surface was determined and the machanism of the transition from the chain structure to the hexagonal (?3??3)R30? structure at coverage increasing to ?=0.33 was established; (4) the order-disorder transition for the (?3??3)R30? structure at the coverage ?=0.33 was investigated; it was shown that when the adlayer consists of domains of ordered structures, the difractional patterns demonstrate the existence of specific splitting of spots with a corresponding decreasing of the intensity of the (?3??3)R30? spots; (5) a role of two-dimensional crowdions in mobility of domain walls in the (?3??3)R30? structure was established, a set of computer programs has been developed, and the dynamics of crowdions was studied with the help of the MD method. Using the physical results of the research on structures and phase transitions in adsorbed layers, recommendations have been formulated for possible practical applications in developing dry cleaning methods in micro- and nano-technologies, designing catalysts and protecting of metals from corrosion in aggresive envirement. Keywords: NANOPHYSICS, PHASE TRANSITIONS, ADSORPTION, SURFACE PHYSICS.
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Браун Олег Михайлович
Зеленська Іріна Ільінічна
Петрова Наталія Вікторівна
Стрижеус Дмитро Вікторович
Яковкін Іван Миколайович
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2020-04-02
