**Titanium (IV) Oxide Nanotubes in Design of Active SERS Substrates for High Sensitivity Analytical Applications: Effect of Geometrical Factors in Nanotubes and in Ag-n Deposits SERS Substrates for High Sensitivity Analytical Applications: Effect of Geometrical Factors in Nanotubes and in Ag-n Deposits**

**Titanium (IV) Oxide Nanotubes in Design of Active** 

DOI: 10.5772/intechopen.72739

Marcin Pisarek, Jan Krajczewski, Marcin Hołdyński, Tomasz Płociński, Mirosław Krawczyk, Andrzej Kudelski and Maria Janik-Czachor Tomasz Płociński, Mirosław Krawczyk, Andrzej Kudelski and Maria Janik-Czachor Additional information is available at the end of the chapter

Marcin Pisarek, Jan Krajczewski, Marcin Hołdyński,

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72739

#### **Abstract**

In this chapter, we summarize the results of recent investigations into TiO2 nanotubular oxide layers on Ti metal loaded with Ag nanoparticles, which act as efficient surface plasmon resonators. These Ag-n/TiO2 NT/Ti composite layers appear to be useful as platforms for precise surface analytical investigations of minute amounts of numerous types of organic molecules: pyridine (Py), mercaptobenzoic acid (MBA), 5-(4-dimethylaminobenzylidene) rhodamine (DBRh) and rhodamine (R6G); such investigations are known as surface enhanced Raman Spectroscopy (SERS). Geometrical factors related to the nanotubes and the silver deposit affect the SERS activity of the resulting composite layers. The results presented here show that, for a carefully controlled amount of Ag-n deposit located mainly on the tops of titania nanotubes, it is possible to obtain high-quality, reproducible SERS spectra for probe molecules at an enhancement factor of 105 –106 . This achievement makes it possible to detect organic molecules at concentrations as low as, e.g., 10−9 M for R6G molecules. SEM investigations suggest that the size of the nanotubes, and both the lateral and perpendicular distribution of Ag-n (on the tube tops and walls), are responsible for the SERS activity. These features of the Ag-n/TiO2 NT/Ti composite layer provide a variety of cavities and slits which function as suitable resonators for the adsorbed molecules.

**Keywords:** TiO2 nanotubes (TiO2 NT), Ag nanoparticles (Ag-n), PVD methods of Ag-n deposition, SERS measurements, enhancement factor (EF )

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© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
