THE EFFECT OF DEFORMATION ON THE LATERAL RESOLUTION OF ATOMIC-FORCE MICROSCOPY

A computer model based on the elastic properties of rubber is introduc ed for the evaluation of the lateral resolution in atomic force micros copy of deformable specimens. The computational results show that, if the full width at half-height can be defined as the lateral resolution , it is continuously improved at greater probe forces, at the expense of a reduced molecular height. In fact, even for a probe that is bigge r than the molecule, the real size of the molecule can be 'recovered' at about 25% compression. This result demonstrates that for a better l ateral resolution, a greater probe force can be beneficial, provided t hat the molecule is not moved or damaged and the response remains elas tic. Measurements on isolated low-density lipoproteins (LDL) show that with 26% vertical compression, the lateral size measured in atomic fo rce microscopy is only about 72% of the value predicted by a simple co nvolution and is only slightly larger (approximate to 13%) than the kn own size of LDL. Therefore, the results on LDL provide a direct suppor t for the conclusions of the computational model.