| We illustrate in Chapter 1 the use of surface-enhanced Raman spectroscopy (SERS) as a molecule-specific probe targeting the detection of mercury ion (Hg2+), copper ion (Cu2+), and lead ion (Pb2+) in aqueous and buffered solutions. The determination of heavy metal ions was achieved by employing 4-mercaptobenzoic acid (pMBA) as the coordination ligand tethered on a SERS active substrate composed of silver nanoparticles (AgNP). Upon interaction with the metal cations, spectroscopic modifications such as changes in peak intensity ratios and peak shifts observed in the SERS spectrum of pMBA were taken as indicators of heavy metal coordination.;In Chapter 2, we confirm the occurrence of Ostwald ripening in pMBA-functionalized silver nanoparticles. We evaluated different parameters, such as light exposure and temperature that may influence this process via UV-visible spectroscopy, dynamic light scattering (DLS), inductively coupled plasma mass spectrometry (ICP-MS), and surface enhanced Raman scattering (SERS) measurements.;Chapter 3 centers on the study of the ionization behavior of 4-mercaptobenzoic acid (pMBA) immobilized on the surface of silver nanoparticles (AgNP). The titration method was performed via SERS and the titration curves were generated by plotting the intensities of the pMBA bands that were responsive to changes in pH of the solution. The percent ionization of pMBA at each stage in the titration process as well as the surface pKa of the molecule were determined in lactic acid, propionic acid, boric acid, and phenol buffer systems. |
