Limits of force microscopy

The atomic force microscope (AFM) is calculated to have quantum limited sensitivity using common optical detection techniques. Under typical ambient operating conditions, the AFM is shown to have an energy resolution better than 10−24 J, considerably weaker than the energy of 10−21 J/molecule for the weakest chemical bonds. For operation in vacuum, periodic forces of 10−15 N are detectable at room temperature. At 4.2 K it is possible to resolve single bursts of energy of 10−25 J. The AFM is shown to have many features in common with a resonant-bar gravitational wave antenna.