Optimized Experimental Designs for Raman Spectroscopy in Different Environments
Steven Yampolsky
Mentor: Vartkess Apkarian
There exist optimized ways of obtaining Raman spectra of various samples in various environments. I will explain and demonstrate, with experimental data, the optimized methods for collecting spectra. For most homogenous samples, to increase the amount of gathered scattering, the excitation that produces the scattering must optimally excite as much volume as possible. To do so, you must put the sample in a capillary and excite the sample such that there will be total internal reflection inside the capillary. For heterogeneous and homogenous samples that are on-resonance with the excitation wavelength, one must implement a confocal Raman Scattering system in which the excitation is focused into a small point inside the sample. This setup is ideal for heterogeneous samples because one can observe the scattering in various points inside the sample. For on-resonance homogenous samples, if the capillary setup is used, the sample will absorb the scattered light used for analysis, therefore a confocal setup is ideal. If you have a sample such as a clathrate that needs to maintain constant temperature inside a bulky cell, or a sample in an environment such as water, confocal geometry in combination with a fiber optic may be used in order to excite the sample and collect the scattering. The fiber optic provides a means of flexibility to adjust the spot sampled with minimal, if any, changes to the alignment of the excitation setup. This study will show some of the optimal ways for gathering
Raman spectra of various samples in various environments.