Figure 2
Mechanical properties of PM2.5 particles measured with AFM.
(a) and (b) three dimensional topographic AFM images of similar PM2.5 particles with flat and rough surfaces respectively (on Silicon substrate); the AFM is able to display the surface roughness with a precision of Angstroms. (c) and (d) SEM and topographic AFM images of PM2.5 soot aggregate with high surface roughness (respectively). (e) Example of force-distance curves measured on particles with different surface roughness (SR); the negative peak of the backward curve corresponds to the AFM tip-sample adhesion force; particles with higher surface roughness usually exhibited larger adhesion forces. The scale bars are 300 nm for (a) and 2.5 μm for (b) 3 μm for (c) 1.1 μm for (d).
