Oxygen exchange between adsorbed NO and MgO surfaces

Three Types of Adsorptions of Nitric Oxide on the MgO Surface

“…The main TPD profiles of N 16 O and N 18 O gases after N 18 O exposure (8.0 × 10 -6 Torr for 3 min) at RT are shown in the insert of Figure 2. 4 Thermal desorptions (TDs) of N 16 O and N 18 O are observed in the temperature region of 350-500 K, while no TD of O 2 was observed. This fact suggests that the adsorbed NO may not dissociate to form N 2 and O 2 species.…”

“…The weak band at 1257 cm -1 (species C) has disappeared below 470 K, suggesting that this species is different from species A‘ and B‘. The main TPD profiles of N 16 O and N 18 O gases after N 18 O exposure (8.0 × 10 -6 Torr for 3 min) at RT are shown in the insert of Figure . Thermal desorptions (TDs) of N 16 O and N 18 O are observed in the temperature region of 350−500 K, while no TD of O 2 was observed.…”

“…Relatively strong and sharp bands of groups A‘ and B‘ are shown. TPD profiles of N 16 O and N 18 O gases after N 18 O exposure (8.0 × 10 -6 Torr for 3 min) at RT from MgO powders are shown in the inset

3 An (MgO) 5 NO geometry optimized with UB3-LYP/6-31G*.

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“…More recently, we have described oxygen isotope exchange between N 18 O and MgO powders using temperatureprogrammed desorption (TPD) measurements, and the exchange process was tentatively explained by NO 2 -type adsorbates and subsequent surface migrations. 4 The determination of vibrational frequencies by ab initio calculations is becoming increasingly important. Theoretically obtained frequencies can be used to predict and assign experimental IR and Raman frequencies.…”

“…However, the atomistic structures of adsorbates including adsorption sites were not determined precisely. More recently, we have described oxygen isotope exchange between N 18 O and MgO powders using temperature-programmed desorption (TPD) measurements, and the exchange process was tentatively explained by NO 2 -type adsorbates and subsequent surface migrations …”