Efficient broken line fitting procedure for analysis of force spectroscopy curves in chemical force microscopy

The procedure for the analysis of force-distance curves in chemical force microscopy is presented. This procedure is based upon the Broken Line Fitting algorithm with an adaptation of knots positions. The strength of this method relies on the fact that it has O(N) complexity, which means that it is as efficient as standard peak detection techniques utilized by commercially available software. It is shown by means of computer simulations that the algorithm is able to detect snap-out points of a height comparable to a noise level, which is a significant improvement in comparison to previously reported techniques. The proposed method is also resistant to base line distortions. Using this procedure for an analysis of CH3-CH3 interactions enabled measurements of interactions between only two molecules, which has been confirmed experimentally. The obtained results strongly support validity of the Johnson-Kendall-Roberts model at the sub-nanometer scale. (C) 2013 AIP Publishing LLC.