Structure, dynamics, and thermodynamics of passivated gold nanocrystallites and their assemblies

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp961721g· OSTI ID:380903

Luedtke, W D; Landman, U ^[1]

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1. Georgia Inst. of Technology, Atlanta, GA (United States)

The structure, dynamics, and thermodynamics of gold nanocrystallites passivated by alkylthiolate monolayers were investigated, using molecular dynamics simulations in different environments, as isolated gas-phase clusters, when adsorbed on a graphite surface and when assembled into three-dimensional superlattices. The packing arrangements and densities of the monolayers passivating the facets of the core gold nanocrystallites differ from those found on extended gold surfaces, exhibiting organization into molecular bundles of preferred orientations which upon heating undergo a reversible melting transition from the ordered bundled state to a uniform intermolecular orientational distribution. The equilibrium geometries of adsorbed nanocrystallites depend on the chain length of the passivating molecules which effectively lubricate the interface between the gold core and the graphite surface conferring high surface mobility to the crystallites, involving a collective slip-diffusion mechanism. The room-temperature equilibrium structure of the superlattice made of Au{sub 140}(C{sub 12}H{sub 25}S){sub 62} nanocrystallites is predicted to be tetragonally distorted fcc with enhanced orientational bundling of the passivating molecules along the direction of the tetragonal distortion. The cohesion of the superlattice derives dominantly from the interactions between the interlocking molecular bundles. 27 refs., 7 figs.

• OSTI ID: 380903
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 32 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
99 GENERAL AND MISCELLANEOUS
CRYSTAL STRUCTURE
CRYSTALS
DYNAMICS
GOLD
MOLECULAR MODELS
ORGANOMETALLIC COMPOUNDS
PASSIVATION
PHYSICAL CHEMISTRY
SIMULATION
STRUCTURAL CHEMICAL ANALYSIS
SUPERLATTICES
THERMODYNAMICS
THIN FILMS