Frequency-modulation atomic force microscopy (FM-AFM) is a highly versatile tool for surface science.
Besides imaging surfaces, FM-AFM is capable of measuring interactions between the AFM probe and the surface
with high sensitivity, which can provide chemical information at sub-nanometer resolution. This is achieved by
deconvoluting the frequency shift, which is directly measured in experiments, into the force between the probe and
sample. At present, the widely used method to perform this deconvolution has been shown to be accurate under
high quality (high-Q) factor vacuum conditions. However, under low quality (low-Q) factor conditions, such as in
solution, it is not clear if this method is valid. A previous study apparently verified this relation for experiments in
solution by comparing the force calculated by this equation with that obtained in separate experiments using the
surface force apparatus (SFA). Here we show that, in solution, a more direct comparison of the force calculated
by this relation with that directly measured by the cantilever deflection in AFM reveals significant differences,
both qualitative and quantitative. However, we also find that there are complications that hinder this comparison.
Namely, while contact with the surface is clear in the direct measurements (including the SFA data), it is less
certain in the FM-AFM case. Hence, it is not clear if the two methods are measuring the same tip-sample distance
regimes. Thus, our results suggest that a more thorough verification of this relation is required, as application of
this formulation for experiments in solution may not be valid.
HE Jian-feng1 (何健锋), HU Jun2 (胡钧), SUN Jie-lin3 (孙洁林), CZAJKOWSKY Daniel M1*
. Re-evaluation of the Widely Applied Force-Frequency Relation for Frequency-Modulation AFM Under Solution[J]. Journal of Shanghai Jiaotong University(Science), 2014
, 19(5)
: 612
-616
.
DOI: 10.1007/s12204-014-1549-8
[1] Binnig G, Quate C F, Gerber C. Atomic force microscopy [J]. Physical Review Letters, 1986, 56(9):930-933.
[2] Giessibl F J. Advances in atomic force microscopy[J]. Reviews of Modern Physics, 2003, 75(3): 949-983.
[3] Gross L, Mohn F, Moll N, et al. The chemical structure of a molecule resolved by atomic force microscopy[J]. Science, 2009, 325(5944): 1110-1114.
[4] Gross L. Recent advances in submolecular resolution with scanning probe microscopy [J]. Nature Chemistry,2011, 3(4): 273-278.
[5] Welker J, Giessibl F J. Revealing the angular symmetry of chemical bonds by atomic force microscopy[J]. Science, 2012, 336(6080): 444-449.
[6] Gross L, Mohn F, Moll N, et al. Bond-order discrimination by atomic force microscopy [J]. Science,2012, 337(6100): 1326-1329.
[7] Wu N, Czajkowsky D M, Zhang J, et al. Molecular threading and tunable molecular recognition on DNA origami nanostructures [J]. Journal of the American Chemical Society, 2013, 135(33): 12172-12175.
[8] Ido S, Kimiya H, Kobayashi K, et al. Immunoactive two-dimensional self-assembly of monoclonal antibodies in aqueous solution revealed by atomic force microscopy[J]. Nature Materials, 2014, 13(3): 264-270.
[9] Lantz M A, Hug H J, Hoffmann R, et al. Quantitative measurement of short-range chemical bonding forces [J]. Science, 2001, 291(5513): 2580-2583.
[10] Kilpatrick J I, Loh S H, Jarvis S P. Directly probing the effects of ions on hydration forces at interfaces[J]. Journal of the American Chemical Society, 2013,135(7): 2628-2634.
[11] Wastl D S, Speck F, Wutscher E, et al. Observation of 4 nm pitch stripe domains formed by exposing graphene to ambient air [J]. ACS Nano, 2013, 7(11):10032-10037.
[12] Ido S, Kimura K, Oyabu N, et al. Beyond the helix pitch: Direct visualization of native DNA in aqueous solution [J]. ACS Nano, 2013, 7(2): 1817-1822.
[13] Giessibl F J. Forces and frequency shifts in atomicresolution dynamic-force microscopy [J]. Physical Review B, 1997, 56(24): 16010-16015.
[14] Giessibl F J. A direct method to calculate tip-sample forces from frequency shifts in frequency-modulation atomic force microscopy [J]. Applied Physics Letters,2001, 78(1): 123-125.
[15] Sader J E, Jarvis S P. Accurate formulas for interaction force and energy in frequency modulation force spectroscopy [J]. Applied Physics Letters, 2004,84(10): 1801-1803.
[16] Uchihashi T, Higgins M J, Yasuda S, et al.Quantitative force measurements in liquid using frequency modulation atomic force microscopy [J]. Applied Physics Letters, 2004, 85(16): 3575-3577.
[17] Israelachvili J, Maeda N, Akbulut M. Comment on reassessment of solidification in fluids confined between mica sheets [J]. Langmuir, 2006, 22(5): 2397-2398.
[18] Hofbauer W, Ho R J, Hairulnizam R, et al. Crystalline structure and squeeze-out dissipation of liquid solvation layers observed by small-amplitude dynamic AFM [J]. Physical Review B, 2009, 80(13): 134104.1-5.
