C2H4 INSERTION INTO ION-BOMBARDED POROUS SILICA

A study via infrared and X-ray-photoelectron spectroscopies of ethylen e reactions with porous silica during high-energy (300 keV) argon bomb ardment in a C2H4 atmosphere, followed by exposure to air at room temp erature or heating at 500 degrees C in a vacuum, is reported. This stu dy has revealed in the as-prepared sample the presence of C = C, C = O , CH2 and CH3 groups. Aging at room temperature in a nitrogen atmosphe re as well as in air produced an increase of CH3 and C = O amount, whi le a heat treatment at 500 degrees C produced the following: the disap pearance of C = C and C = O groups, an increase in the CH2 amount, and a decrease in the CH3 amount. An interpretation for this behaviour is proposed. A previous conclusion concerning CO2 addition to ion-bombar ded porous silica, that approximately 10(2) oxygen-bridge vacancy per impinging ion are stabilized through the addition of gas molecules, is confirmed by the present work.