A TEMPERATURE-PROGRAMMED DESORPTION TECHNIQUE FOR STUDYING SURFACE CONTAMINATION AND ACID-BASE PROPERTIES OF THICK METAL SHEETS

This paper describes how the temperature-programmed desorption (TDP) t echnique, which is widely used in the fields of surface science and ca talysis, has been newly adapted to investigate the thick metallic shee t samples of about 10 cm(2) area used in adhesion studies. A high freq uency induction system has been designed in order to achieve a high he ating tate (up to 200 K.s(-1))without creating substantial temperature gradients in the sheet The sample is placed in a secondary vacuum rea ctor and the gas desorbed is analysed by means of a quadrupole mass sp ectrometer. The results presented deal with stainless steel and chromi um surfaces, subjected to various chemical treatments. The sensitivity and the resolution of the technique presented are shown to be suffici ent to study metallic surface contamination and to characterise the ac id sites at the surface by desorption of a basic probe molecule such a s ammonia.