Abstract
The atomic force microscope (AFM) is capable of measuring the interaction between tip and sample with high sensitivity and unparalleled spatial resolution. The chemical functionalization of the AFM tips has expanded the versatility of the AFM to experiments where specific molecular interactions are measured. We present here measurements of the interaction between complementary strands of DNA. A necessary prerequisite for the quantitative analysis of the interaction force is knowledge of the spring constant of the cantilevers. We report a method that allows for the in situ measurement of the absolute value of the spring constant of cantilevers based on spectral analysis of the thermal excitations of the cantilever.
