Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 87: Focussed Session: Solid-liquid Interfaces III

O 87.6: Talk

Friday, March 15, 2013, 11:45–12:00, H31

Molecular dynamics simulation of interfaces of gold nanorods — •Santosh Meena and Marialore Sulpizi — Condensed Matter Theory, Institute of Physics, Johannes Gutenberg University, Staudingerweg 7, 55128 Mainz, Germany

Nanorods are widely used in many areas such as drug delivery, photothermal cancer therapy, biochemical sensing and medical imaging. Growth of nanorods starts from small reasonably uniform gold seeds in a widely employed experimental technique, seed-mediated growth. In this technique ascorbic acid (a mild reducing agent), is added to aqueous cetyltrimethylammonium bromide (CTAB) solution of HAuCL4 for selective reduction of Au(III) to Au(I), followed by the addition of the seed solution which catalyze the reduction of Au(I) on their surface. Isotropic morphology breaking of the seeds results into anisotropic growth and thus formation of nanorods. However, the microscopic mechanism of symmetry breaking and anisotropic growth is still unknown. Therefore, we studied the adsorption mechanism of CTAB surfactant on different facets of gold, namely 110, 100 and 111 using molecular dynamics (MD) simulation. Atomistic models for different gold surfaces with CTAB surfactant in water were built using GROMOS 53A6 force-field parameters. Properties like, number densities of species and electrostatic potential were calculated across the gold-CTAB and CTAB-water interfaces in order to understand the adsorption of CTAB on the different gold surfaces. Higher density of adsorbed species were found on 110 and 100 facets than 111, this possibly results growth of the nanorod more in the direction of 111 facet.