The intense local field induced near metallic nanostructures provides strong enhancements for surface enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we show several different nanoantennas for SEIRA detection, which exhibit an order of magnitude greater SEIRA sensitivity than previous record-setting designs. We also consider that plasmonic nanoparticles can induce remarkably large electromagnetic field gradients near their surfaces, which can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. Finally, we introduce a new technique that can demonstrate the mapping of electromagnetic forces between a nanoscale tip and an optically excited sample consisting of plasmonic nanostructures with an imaging platform based on atomic force microscopy.