Dresden 2011 – scientific programme

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MO: Fachverband Molekülphysik

MO 15: Linear and nonlinear Raman Spectroscopy

MO 15.4: Talk

Wednesday, March 16, 2011, 15:30–15:45, MER 02

Complex Concentration Dependence of Glycine-Induced Structural Modification of Silver Nanoparticles Investigated by UV-VIS, SERS, and TEM — •Patrice Donfack¹, Animesh K. Ojha^1,2, and Arnulf Materny¹ — ¹Center of Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany — ²Department of Physics, Motilal Nehru National Institute of Technology, Allahabad, India

In this contribution, we report a complex concentration-dependence of surface-enhanced Raman scattering (SERS) and UV-VIS absorption of Ag-nanoparticles (AgNPs) mixed with glycine (Gly). Surprisingly, while decreasing the Gly concentration, a new band in the UV-VIS absorption spectrum of AgNPs/Gly mixtures is found, which is red-shifting with increasing intensity, until a turning point at a critical concentration is reached. Upon further dilution of Gly, the new band blue-shifts with decreasing intensity. Similarly, the SERS intensities of the Gly bands at 615 and 905 cm⁻¹ consistently increase with decreasing Gly concentrations, reaching maxima at the critical concentration point. This agrees consistently with the variation in position and intensity of the newly developing plasmon absorption band. Interestingly, transmission electron microscopy (TEM) reveals Gly-mediated modifications of AgNPs, which includes a re-assembling and an increasing aspect ratio with deceasing Gly concentration.