“…The ratio I(D)/I(D′) can be used to obtain valuable information in this regard (42,47). It has been reported that I(D)/I(D′) is ~13 for sp 3 defects, ~10 for sp 2 -related defects, and ~7 for void defects. I(D)/I(D′) was observed to be ~10, ~7, ~13, and ~21 for Cr40, Cr80, Cr120, and Cr150, respectively.…”