In-situ Raman spectroscopic measurements of the deformation region in indented glasses
Yvonne B. Gerbig, Chris A. Michaels
This paper describes the design and integration of a custom-built optical instrument for in- situ Raman microscopy suitable for collecting high-quality spectroscopic data during the indentation of glass materials. It will further show that the reported experimental setup enables meaningful in-situ spectroscopic observations during indentation of fused silica at forces in the milli-newton range. The aim of the paper is to demonstrate the vital importance of matching the analysis volume of the Raman microscopewith the indentation-induced deformation volume to capture the full extent of spectral alterations due to the deformed material by minimizing spectral contributions from the unperturbed bulk material (in-situ and ex-situ) and indenter probe (in-situ only). In this context, the paper will also touch upon possible pitfalls in ex-situ and in-situ Raman measurements on indented glasses in cases where the analysis and deformation volumes are not well matched and describe the misinterpretations that may result.