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Ag and Au nanoparticles for SERS substrates produced by pulsed laser ablation
Author(s) -
Agarwal N. R.,
Fazio E.,
Neri F.,
Trusso S.,
Castiglioni C.,
Lucotti A.,
Santo N.,
Ossi P. M.
Publication year - 2011
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.201000588
Subject(s) - fluence , laser , laser ablation , materials science , nanoparticle , pulsed laser deposition , analytical chemistry (journal) , raman spectroscopy , surface enhanced raman spectroscopy , wavelength , plume , deposition (geology) , thin film , optics , optoelectronics , nanotechnology , chemistry , raman scattering , paleontology , sediment , biology , thermodynamics , physics , chromatography
A method for the growth of films consisting of Nanoparticles (NP) of Ag and Au is presented. Nanostructured films were obtained by means of nanosecond pulsed laser ablation of a metallic target in presence of a controlled Ar atmosphere. The morphology of these films from island structures to isolated nanoparticles, measured by SEM, depends on the varying gas pressure (10‐100 Pa) and on the number of laser pulses (500‐30000), keeping other deposition parameters such as the target to substrate distance, incidence angle, laser wavelength, laser fluence constant. Fast imaging of the plasma, performed using a intensified and gateable CCD camera at different time delays with respect to the arrival of the laser pulse, allows revelation of the propagation regime of the ablation plume and inference of plasma initial velocity. This data along with the measured average ablated mass per pulse were taken as inputs to a model to estimate the average size of NPs grown in the expanding plume. The theoretical NP sizes were compared with sizes measured from TEM images. These images indicate narrow gradients of NP sizes. Hence strict control of growth parameters aids fine tuning of NP size that is essential for many applications, including Surface Enhanced Raman Spectroscopy (SERS) active substrates. UV‐Visible Spectroscopy helped in determination of appropriate laser wavelength for resonant excitation of the localized surface plasmon. SERS Spectra obtained with increasingly lower concentrations of reference dye Rhodamin 6G (Rh6G) and medical drug Apomorphine, are discussed as a perspective of application to biomedical sensors. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)