Optimum topographical and morphological information in AFM tapping mode investigation of multicomponent polyethylene

For systematic AFM tapping mode studies of a binary blend of multicomponent polyethylene height and phase images were recorded at different set-point amplitude ratios rsp ranging from 0.95 to 0.1. Force-probe mode measurements were carried out both in stiff and soft regions of the blend. Based on the resulting amplitude/phase versus distance curves a contrast interpretation of the height and phase images at different rsp was carried out. In agreement with the results of several authors it was demonstrated that only at light tapping, with rsp close to 1, does the profile in the height image present a true surface topography, whereas with rsp≈0.5 much harder tapping is necessary, so that maximum phase contrast is observed. Therefore, interleave scanning with lighter and harder tapping in the main and interleaved scans, respectively, was used to simultaneously record height and phase images with optimum topographical and morphological information, respectively. Furthermore, interleave scanning combined with negative lift mode was used to make local changes in indentation visible.