PHOTOELECTRON AND NEXAFS MICROSCOPY OF RADIATION-INDUCED CHANGES IN CADMIUM ARACHIDATE FILMS

The radiation induced changes caused by both low energy Ar+ ion bombar dment and high energy H+ ion bombardment on Langmuir-Blodgett (LB) fil ms of cadmium arachidate were investigated using a commercial photoele ctron microscope installed at the German synchrotron facility BESSY. F or the low energy situation, XPS imaging was performed using damage in duced differential charging as the contrast mechanism. The high energy H+ bombardment produced less damage and no resolvable charging shift, so this contrast mechanism cannot be used for imaging. However, chemi cal shifts in the C NEXAFS (near edge X-ray absorption fine structure) , caused by the H+ bombardment, are sufficiently large to use as a con trast mechanism. NEXAFS, of course, requires tunable radiation and hen ce spectromicroscopy in conjunction with synchrotron radiation offers the possibility for imaging chemical changes in organic films which ar e not observable using fixed energy laboratory sources. In principle, molecular orientation changes are also imageable, as the relative inte nsities of different features in a NEXAFS spectrum often vary with ori entation.