THE STRUCTURE AND CORROSION CHEMISTRY OF BROMINE ON PT(111)

The corrosive adsorption of Pr atoms on Pt(111) was studied by variabl e temperature STM, TPD and AES. Photoinduced dissociative electron att achment to adsorbed CH3Br at 193 nm was used to dose hot Br anions ont o the surface at 90 K. Br formed two ordered structures on Pt(111): (3 x 3) and (root 3 x root 3)R30 degrees. STM images showed that both st ructures can coexist at intermediate coverage. Photofragmentation of C H3Br produced Pt atom monovacancies on the Pt(111) surface which were attributed to abstractive attack by the hot Pr anions. The initial mon ovacancy etching efficiency of the adsorbing Pr anions was high, rough ly 33%. (C) 1998 Elsevier Science B.V. All rights reserved.