Abstract
The operational characteristics and imaging performance are described for a new instrument comprising an atomic force microscope (AFM) coupled with a pulsed laser and a linear ion trap mass spectrometer. The AFM operating mode is used to produce topographic surface images having nanometer-scale spatial and height resolution. Spatially resolved mass spectra of ions, produced from the same surface via microprobe-mode laser desorption/ionization at atmospheric pressure, are then used to create a 100 x 100 μm chemical image. The effective spatial resolution of the image (~2 μm) was constrained by the limit of detection (estimated to be 109 – 1010 ions) rather than by the diameter of the focused laser spot or the step size of the AFM sample stage. Thus, it is expected that improvements in imaging performance can be realized by implementation of post-ionization methods.
