The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample surfaces.At present,studies regarding the energy dissipation mechanism of this ...The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample surfaces.At present,studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically,and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous process.The quality factors can be used to characterize the energy dissipation in TM-AFM systems.In this study,the vibration model of the microcantilever beam was established,coupling the vibration and damping effects of the microcantilever beam.The quality factor of the vibrating microcantilever beam under damping was derived,and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were calculated.In addition,the mechanism of the damping effects of different shapes of probes at different tip–sample distances was analyzed.The accuracy of the theoretical simplified model was verified using both experimental and simulation methods.A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode,which was very important for improving both the quality factor and the imaging quality of the TM-AFM system.This study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.展开更多
Phase image in tapping-mode atomic force microscope(TM-AFM)results from various dissipations in a microcantilever system.The phases mainly reflect the tip-sample contact dissipations which allow the nanoscale characte...Phase image in tapping-mode atomic force microscope(TM-AFM)results from various dissipations in a microcantilever system.The phases mainly reflect the tip-sample contact dissipations which allow the nanoscale characteristics to be distinguished from each other.In this work,two factors affecting the phase and phase contrast are analyzed.It is concluded from the theoretical and experimental results that the phases and phase contrasts in the TM-AFM are related to the excitation frequency and energy dissipation of the system.For a two-component blend,it is theoretically and experimentally proven that there exists an optimal excitation frequency for maximizing the phase contrast.Therefore,selecting the optimal excitation frequency can potentially improve the phase contrast results.In addition,only the key dissipation between the tip and sample is found to accurately reflect the sample properties.Meanwhile,the background dissipation can potentially reduce the contrasts of the phase images and even mask or distort the effective information in the phase images.In order to address the aforementioned issues,a self-excited method is adopted in this study in order to eliminate the effects of the background dissipation on the phases.Subsequently,the real phase information of the samples is successfully obtained.It is shown in this study that the eliminating of the background dissipation can effectively improve the phase contrast results and the real phase information of the samples is accurately reflected.These results are of great significance in optimizing the phases of two-component samples and multi-component samples in atomic force microscope.展开更多
基金the National Natural Science Foun-dation of China(Grant No.11572031).
文摘The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample surfaces.At present,studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically,and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous process.The quality factors can be used to characterize the energy dissipation in TM-AFM systems.In this study,the vibration model of the microcantilever beam was established,coupling the vibration and damping effects of the microcantilever beam.The quality factor of the vibrating microcantilever beam under damping was derived,and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were calculated.In addition,the mechanism of the damping effects of different shapes of probes at different tip–sample distances was analyzed.The accuracy of the theoretical simplified model was verified using both experimental and simulation methods.A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode,which was very important for improving both the quality factor and the imaging quality of the TM-AFM system.This study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.
基金the National Natural Science Foundation of China(Grant No.11572031)。
文摘Phase image in tapping-mode atomic force microscope(TM-AFM)results from various dissipations in a microcantilever system.The phases mainly reflect the tip-sample contact dissipations which allow the nanoscale characteristics to be distinguished from each other.In this work,two factors affecting the phase and phase contrast are analyzed.It is concluded from the theoretical and experimental results that the phases and phase contrasts in the TM-AFM are related to the excitation frequency and energy dissipation of the system.For a two-component blend,it is theoretically and experimentally proven that there exists an optimal excitation frequency for maximizing the phase contrast.Therefore,selecting the optimal excitation frequency can potentially improve the phase contrast results.In addition,only the key dissipation between the tip and sample is found to accurately reflect the sample properties.Meanwhile,the background dissipation can potentially reduce the contrasts of the phase images and even mask or distort the effective information in the phase images.In order to address the aforementioned issues,a self-excited method is adopted in this study in order to eliminate the effects of the background dissipation on the phases.Subsequently,the real phase information of the samples is successfully obtained.It is shown in this study that the eliminating of the background dissipation can effectively improve the phase contrast results and the real phase information of the samples is accurately reflected.These results are of great significance in optimizing the phases of two-component samples and multi-component samples in atomic force microscope.
