Improved methodology for monitoring deposition or removal of material to or from a process and/or wittness substrate which demonstrates a negative e1 at some wavelength. The method involves detection of changes in P-polarized electromagnetism ellipsometric DELTA at SPR Resonance Angle-of-Incidence (AOI) to monitor deposition of and/or removal of minute amounts of materials onto, or from, said process and/or witness substrate. The methodology can optionally monitor ellipsometric PSI, and involves simultaneously or sequentially applying non-P-polarized electromagnetism at the same angle of incidence, or electromagnetic radiation of any polarization at a different angle-of-incidence and wavelength to the process or wittness substrate and application of conventional ellipsometric analysis.