High Density Periodic Metal Nanopyramids for Surface Enhanced Raman Spectroscopy

The work presented in this thesis is focused on two areas. First, a new type of nanotextured noble-metal surface has been developed. The new nanotextured surface is demonstrated to enhance inelastic (Raman) scattering, called surface enhanced Raman scattering (SERS), from molecules adsorbed on the metal surface due to large electromagnetic fields generated in nanoscale gaps by an external laser excitation source. By detecting the enhanced Raman scattered photons, the molecular bond information can be analyzed using methods from conventional Raman spectroscopy. Raman spectroscopy is very powerful analytical method in chemistry, biology and other scientific areas, since it provides molecular vibrational information, which is considered a fingerprint for a particular molecule. Raman spectroscopy is less commonly used compared to other analytical methods, such as infrared spectroscopy, due to its extremely weak signal. For example, a typical molecule excited with ~1 mW laser excitation will scatter ~10-6 photons s-1 molecule-1 1, which requires a large number of molecules