Atomic photo-absorption force microscope.

摘要

An Atomic Photo-Absorption Force Microscope 1 includes an Atomic Force Microscope 10 and a radiation source 20 having an output radiation 22 wavelength selected to be preferentially absorbed by atoms or molecules associated with a sample surface 24a under investigation. Absorption of the radiation raises at least one outer shell electron to a higher energy level, resulting in an increase in radius of the atom or molecule. A tip 12 coupled through a lever 14 to the Atomic Force Microscope 10 is scanned over the surface and operates in conjunction with a laser heterodyne interferometer 18 to directly measure the resulting atomic or molecular increase of size, thereby detecting both the presence and location of the atoms or molecules under investigation. Operation in an a.c. mode by chopping the incident radiation 22 and measuring the corresponding a.c. induced tip movement beneficially increases the sensitivity of the technique, particularly if the a.c. frequency is chosen at a resonance of the tip-lever combination.