Indirect modulation of nonmagnetic probes for force modulation atomic force microscopy.
Frequency-dependent changes for phase and amplitude images are demonstrated with test platforms of organosilane ring patterns, using force modulation atomic force microscopy (FM-AFM) with an alternate instrument configuration. The imaging setup using indirect magnetic modulation (IMM) is based on indirect oscillation of soft, nonmagnetic cantilevers, with spring constants <1 N m(-1). The tip is driven to vibrate by the motion of a tip holder assembly which contains ferromagnetic materials. The entire tip assembly is induced to vibrate with the flux of an external ac electromagnetic field, supplied by a wire coil solenoid placed underneath the sample plate. With the use of IMM, dynamic parameters of the driving frequencies and amplitude of the tip motion can be optimized to sensitively map the elastic response of samples. An advantage of this instrument setup is that a magnetic coating is not required to drive the periodic oscillation of the tip. The instrument configuration for IMM may not be practical for intermittent imaging modes, which often work best with stiff cantilevers. However, indirect actuation provides an effective approach for imaging with low force setpoints and is well-suited for dynamic AFM modes using continuous contact imaging.
Li
Jie-Ren
JR
Department of Chemistry and the Center for BioModular Multi-Scale Systems, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803, USA.
Garno
Jayne C
JC
D004574:Electromagnetic Fields; D008280:Magnetics; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force / Q000379:methods*; D017646:Organosilicon Compounds / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D015203:Reproducibility of Results; D012821:Silanes / Q000737:chemistry; D013499:Surface Properties; D014732:Vibration
D017646:Organosilicon Compounds; D012821:Silanes; D011092:Polyethylene Glycols