CO2 INSERTION INTO ION-BOMBARDED POROUS SILICA

The damage imparted to porous silica by argon bombardment is stabilize d and marked by carrying out the bombardment in a controlled CO2 atmos phere. IR spectroscopy shows that CO2 is inserted via the formation of carboxylate groups which, on heat treatment at 500 degrees C, are con verted to ester-like groups and, eventually, after exposure to wet air , to carboxylic groups. Dehydration of these structures restores the e ster sites almost reversibly.