Observation by transmission electron microscopy of etch figures obtained on an organic molecular crystal.

It is interesting to apply the method of etch figures to the study of organic molecular crystal defects, by observing the etch pits as soon as they are produced. We have set up a method to determine the geometrical forms of such small etch pits, observed on pre-shadowed replicas of naphthalene crystal surfaces. The described experimental procedure was designed to avoid artefacts due to vacuum sublimation and moisture traces on the replicated surface. Stereoscopic observation makes interpretation possible. The 3-D morphology and size of etch figures smaller than 1 micron can be determined.