Mössbauer method for measuring subangstrom displacements of thin films

The first results of Mössbauer spectroscopy measurements of the distribution of the amplitude of mechanical vibrations of a 25-$\mu$m-thick stainless steel foil along its surface are presented. The gamma radiation of $^{57}$Co with a wavelength of 86 pm has been used for the measurements. Sample vibrations along the direction of gamma radiation propagation have been induced using a polymer piezoelectric transducer. At moderate applied voltages, the measured oscillation amplitude does not exceed 50 pm. The measurement accuracy of the vibration-amplitude distribution along the foil surface is 3–6 pm. This method is proposed to create standards of mechanical displacements that can be used to calibrate tunneling microscopes.