Figure 1: MoS2 band sedimentation and size-dependent extinction spectra.
(a) Experimental setup for band sedimentation centrifugation involving layering a nanomaterial stock dispersion on top of a race layer. Centrifugation leads to spreading of the material throughout the vial and separation of the nanosheets according to their sedimentation velocities and so their size. Fractions as indicated are withdrawn from top to bottom. (b) Extinction spectra of the fractions normalized to the local minimum at 345 nm. The positions of the A- and B-excitons are marked. (c) Ratio of extinction at B-exciton to that at 345 nm, ExtB/Ext345 plotted versus fraction number. (d) Peak position (wavelength) of the A-exciton, λA, as a function of fraction number. We propose that λA and ExtB/Ext345 can be used as metrics for flake thickness and length, respectively.
