Oxygen Adsorption on the (110)-Oriented Diamond Surface

Abstract

Multiple internal reflection infrared spectroscopy (MIRIRS) and temperature-programmed desorption (TPD) were used to investigate the interaction of oxygen with a diamond (110)-oriented surface. Exposure of the hydrogen-free diamond surface at 90 K to room-temperature O 2 or thermally excited oxygen, O 2 * (produced with a heated iridium filament) resulted in a sharp infrared absorption at 657 cm -1 , which disappeared on heating to 300 K. The 657 cm -1 absorption may indicate a surface peroxide. When the hydrogen-free diamond surface was dosed with O 2 at room temperature, no oxygen adsorption was observed by Auger electron spectroscopy (AES) or TPD. In contrast, dosing the surface with O 2 * at 300 K led to oxygen chemisorption. The room-temperature diamond surface was saturated with oxygen after exposures of >2400 L O 2 *. When the oxidized surface was heated, only CO 2 and CO desorption were observed, with peak maxima at 780 and 870 K, respectively. The peak desorption temperatures for CO 2 and CO did not vary with O coverage, implying first-order desorption kinetics. MIRIR spectra of the oxygen-saturated (110)-oriented surface showed weak absorption modes at 790 and 980 cm -1 . The exposure of the surface at 900 K to O 2 * led to (1) an increase in the coverage of oxygen species stable at high-temperature, (2) narrower, more intense, MIRIRS absorption modes ( 16 O, 770, 934, and 980 cm -1 ; 18 O, 747, 895, and 936 cm -1 ) and (3) a sharp, intense CO desorption peak at 1025 K. These observations imply that the low-temperature adsorption sites were etched away, thus favoring the additional adsorption of oxygen into the adsorption sites that are stable at high temperature. † Part of the special issue "John T. Yates, Jr. Festschrift".

Formation of surface oxides and Ag2O thin films with atomic oxygen on Ag(111)

“…Finally, these conditions were repeated with a Ni(110) sample; no O 2 desorption was observed in TPD measurements and no Ir was observed in the Auger spectra. Other studies using Ir filaments to generate AO have also reported no appreciable Ir accumulation from a hot Ir filament [45]. These control experiments verify that the TPD and AES uptakes observed are the result of the interaction of AO with Ag(111).…”

Effect of oxygen on field emission properties of ultrananocrystalline diamond-coated ungated Si tip arrays

“…This phenomenon has also been observed by Chalamala 1 on Mo tip arrays and indicates that at room-temperature O 2 molecules were unable to form a stable adsorbed species on the UNCD surface. The observation is in agreement with that of Mackey et al, 18 and will be discussed next.…”

“…4͑b͒. The desorbed species were not clear at this stage, but possible in the form of O 2 or CO/CO 2 as observed by Mackey et al 18 Figures 4͑a͒ and 4͑b͒ represent two extreme cases: Recoverable and permanent damage to the UNCD coated tip emitters operated at a relatively low and high current due to O 2 exposure.…”

“…On the other hand, over the past years, there were several reports on the interaction of oxygen with single and polycrystalline diamond surfaces. [17][18][19] Hossain et al 17 reported chemisorbed states of atomic O on the diamond ͑100͒-͑2ϫ1͒ surface. Mackey et al 18 found that no oxygen adsorption was observed by Auger electron spectroscopy and temperature-programmed desorption when the hydrogen-free diamond ͑110͒ surface was dosed with O 2 at room temperature, whereas adsorbed atomic O species were desorbed as CO and CO 2 .…”

“…[17][18][19] Hossain et al 17 reported chemisorbed states of atomic O on the diamond ͑100͒-͑2ϫ1͒ surface. Mackey et al 18 found that no oxygen adsorption was observed by Auger electron spectroscopy and temperature-programmed desorption when the hydrogen-free diamond ͑110͒ surface was dosed with O 2 at room temperature, whereas adsorbed atomic O species were desorbed as CO and CO 2 . In a study of surface reactivity of diamond photocathodes with molecular and atomic oxygen species, Foord et al 19 observed that the chemical vapor deposition ͑CVD͒ diamond film showed a low but measurable reactivity with O 2 , whereas the reaction probability of Ir excited O 2 was significantly higher than that of molecular oxygen.…”