为了兼顾非接触式原子力显微镜(noncontact atomic force microscope,NC-AFM)更高谐振频率探针的使用需求,并通过提高控制器精度进而提高NC-AFM分辨率,提出了一种基于探针-样品间原子作用力变化的全数字可调谐NC-AFM高分辨率探针起振系...为了兼顾非接触式原子力显微镜(noncontact atomic force microscope,NC-AFM)更高谐振频率探针的使用需求,并通过提高控制器精度进而提高NC-AFM分辨率,提出了一种基于探针-样品间原子作用力变化的全数字可调谐NC-AFM高分辨率探针起振系统。在Simulink环境下对探针起振系统的控制部分进行了设计,通过现场可编程门阵列(FPGA)实现了鉴相,滤波,锁频等功能;采用压电陶瓷片驱动探针振动,设计了操作便捷的探针座。将不同频率正弦信号提供给设计的起振系统进行功能性验证,实验结果表明,系统可以在20 kHz~50 MHz频率范围内跟踪探针谐振频率;最后使用起振系统成功使商用探针在谐振频率处振动,准确测出了探针的谐振频率及振动幅值,系统频率分辨率达到了0.1 Hz。展开更多
We investigated the orientations of interface dipole moments of individual non-planar titanyl phthalocyanine(TiOPc)molecules on Cu(111)and Cu(100)substrates using scanning tunneling microscope(STM)and noncontact atomi...We investigated the orientations of interface dipole moments of individual non-planar titanyl phthalocyanine(TiOPc)molecules on Cu(111)and Cu(100)substrates using scanning tunneling microscope(STM)and noncontact atomic force microscope(NC-AFM).The dipole moment orientations corresponding to two different configurations of individual TiOPc molecules were determined unambiguously.The correlation between the actual molecular structures and the corresponding STM topographies is proposed based on the sub-molecular resolution imaging and local contact potential difference(LCPD)measurements.Comparing with the pristine substrate,the LCPD shift due to the adsorption of non-planar molecule is dependent on the permanent molecular dipole,the charge transfer between the surface and the molecule,and the molecular configurations.This work would shed light on tailoring interfacial electronic properties and controlling local physical properties via polar molecule adsorption.展开更多
基金supported by the National Basic Research Program of China(2012CB933001)the National Natural Science Foundation of China(21173058,21203038)
文摘We investigated the orientations of interface dipole moments of individual non-planar titanyl phthalocyanine(TiOPc)molecules on Cu(111)and Cu(100)substrates using scanning tunneling microscope(STM)and noncontact atomic force microscope(NC-AFM).The dipole moment orientations corresponding to two different configurations of individual TiOPc molecules were determined unambiguously.The correlation between the actual molecular structures and the corresponding STM topographies is proposed based on the sub-molecular resolution imaging and local contact potential difference(LCPD)measurements.Comparing with the pristine substrate,the LCPD shift due to the adsorption of non-planar molecule is dependent on the permanent molecular dipole,the charge transfer between the surface and the molecule,and the molecular configurations.This work would shed light on tailoring interfacial electronic properties and controlling local physical properties via polar molecule adsorption.
