X-RAY PHOTOELECTRON-SPECTROSCOPY ANALYSIS OF ALUMINUM AND COPPER CLEANING PROCEDURES FOR THE ADVANCED PHOTON SOURCE

The Advanced Photon Source (APS), presently under construction, will p roduce x rays of unprecedented brightness. The storage ring where the x rays will be produced will be constructed from an extruded 6063 alum inum alloy, while transition pieces (flanges, etc.) will be made from a 2219 aluminum alloy. In addition, cooled photon absorbers will be pl aced in strategic locations throughout the ring to intercept the major ity of the unused high power-density radiation. These will be made of either CDA-101 (OFHC) copper or glidcop (a dispersion strengthened cop per alloy). Before any of these components can be assembled they must be cleaned to remove surface contaminants so that the ultrahigh vacuum (<0.1 nTorr) necessary for successful operation can be achieved. Many recipes for cleaning aluminum and copper exist; however, most of them involve the use of chemicals that present safety and/or environmental concerns. We have undertaken an x-ray photoelectron spectroscopy stud y of the effects of a variety of commercially available cleaners on th e surface cleanliness of aluminum and copper. Several important result s have been identified in this study. A simple alkaline detergent in a n ultrasonic bath cleans aluminum alloys as effectively as the more ag gressive cleaning solutions. The detergent can be used at 65-degrees-C to clean the 6063 alloy and at 50-degrees-C to clean the 2219 alloy. A citric acid based cleaner was found to be effective at cleaning copp er, although the surface oxidizes rapidly. To date, we have been unabl e to find a universal cleaning procedure, i.e., one that is optimal fo r cleaning both Al and Cu.