Noncontact Atomic Force Microscopy - Yale School of Engineering ...

Atomic resolution dynamic lateral force microscopy in liquid
Shuhei Nishida, Dai Kobayashi, Noriyuki Okabe, and Hideki Kawakatsu
Fr-1120
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
snishida@iis.u-tokyo.ac.jp
A key step to achieve atomic resolution imaging in dynamic lateral force
microscopy (DLFM) is to reduce the lateral tip amplitude down to less than atomic lattice
scale of the sample. Use of high-frequency cantilever vibration modes is effective for
reducing the tip amplitude. In this contribution, we demonstrate atomic resolution DLFM
imaging in liquid using a high-frequency torsional mode.
We performed the DLFM imaging using an optically based method combining
photothermal excitation and laser Doppler velocimetry for utilizing various cantilever
vibration modes [1,2]. We excited and detected the first torsional mode with the
resonance frequency of 1.15 MHz, and reduced the lateral tip amplitude down to 1.3 Å
with keeping vibration stability.
Figure 1(a) shows a DLFM image of a muscovite mica surface immersed in purified
water. The small tip amplitude around a quarter of the mica’s lattice constant allowed us
to achieve atomic resolution imaging. Cross sectional analysis of the image at the
meandering features suggests that the force acting on the tip from a tetrahedral silicate
group was overlapped with the force from the neighboring silicate group along the
vibration direction (Fig. 1(b)).
(a) (b)
Figure 1: DLFM imaging of a muscovite mica surface immersed in purified water. (a) A
topographic image, drive frequency: 1,158,225 Hz, scan size: 10 x 10 nm 2 . (b) A line profile
along the solid line in (a).
[1] S. Nishida, D. Kobayashi, T. Sakurada, T. Nakazawa, Y. Hoshi, and H. Kawakatsu, Rev. Sci. Instrum.
79, 123703 (2008).
[2] S. Nishida, D. Kobayashi, H. Kawakatsu, and Y. Nishimori, J. Vac. Sci. Technol. B 27, 964 (2009).
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