Extended Data Fig. 6: HIM and Raman analysis of the bombarded region of graphene-covered fixed HDF cells.
From: Mass spectrometry imaging of untreated wet cell membranes in solution using single-layer graphene
a–c, HIM images of the bombarded region of the sample. The bombarded region appears to be a dark square indicated by white-dotted lines in ToF-SIMS analysis (a). The appearance of the dark spots for each pixel suggests the decrease of secondary electron yields in the HIM imaging due to an increase of the work function with the graphene oxide formation (b). Magnified HIM image of one bombarded dark spot shows no noticeable damage in graphene at the 1.93 × 1014/cm2 ion dose (c). d, ToF-SIMS total negative ion image of the sample corresponding to the HIM image in a. e, Raman analysis of the ion-bombarded region of graphene clearly shows the formation of graphene oxide in contrast to the non-bombarded region of pristine graphene. The graphene oxide may be formed by the ion-beam-induced reaction between graphene and water molecules beneath the graphene. Results presented are obtained from a single experiment.
