Raman spectra were obtained using a Renishaw Invia microscope with a laser generating 633 nm (red) light delivering 13.0 mW at the sample. The laser power was set to 10% with the exposure time of 60s and one accumulation. All measurements were done under room temperature in a sealed homebuilt sample holder with a quartz window in the range of 100 to 3200 cm -1 . Baseline corrections and normalization were applied to the spectra. The Voigt function was used to deconvolute bands into constituent peaks.