Realization of Platinum Nitride and Study of reaction with gas molecules

本研究的目的是实现通常无法构建的氮化铂。吸附在Pt（111）上的一氧化氮（NO）在紫外光或电子照射下发生解离。为此，研究了NO在Pt（111）上的吸附和解吸，以及紫外和电子辐照下的解吸/解离。Pt虽然具有催化能力，但NO不能在Pt（111）上解离，只能在低温下吸附并加热解吸。当NO覆盖率增加时，NO首先吸附在3层fcc中空位点上，其次吸附在1层atop上，最后吸附在3层hcp中空位点上。从热脱附光谱（TDS）的脱附峰得到吸附能。利用NO同位素14NO和15NO精确研究了吸附在不同位点上的NO之间的相互作用。利用扫描隧道显微镜（STM）观察了吸附结构，并通过扫描隧道显微镜尖端的电子注入研究了电子辐照的效果。STM顶端的NO可以被STM尖端的电子辐射解吸，而fcc中空部位的NO则可以被15ev以上的电子辐射解离。辐照后的STM观察发现许多小波纹，可能是NO的解离产物。NO物质占据hcp中空位点，虽然其吸附能很小，但影响了NO在fcc中空位点和顶部位点上的扩散。提示NO对P1（111）的活性可通过NO对hcp空心位点的占据来控制。

The purpose of this study is to realize the platinum nitride which cannot be constructed by usual way. When nitric oxide (NO) adsorbed on Pt(111) is irradiated by ultra-violet (UV) light or electron, it is suggested to be dissociated. For this purpose the adsorption and desorption of NO on Pt(111), and the desorption/dissociation by UV or electron irradiation was studied.In spite of the catalytic ability of Pt, NO cannot be dissociated on Pt(111), it just adsorbs at low temperature and desorbs by heating. When the NO coverage is increased, NO first adsorbs on the 3-fold fcc hollow site, next on the 1-fold atop site and last on the 3-fold hcp hollow site. The adsorption energy was obtained from the desorption peak in the thermal desorption spectra (TDS). The interaction between the NO species adsorbed on the different sites was precisely studied by using the NO isotopes, 14NO and 15NO. The adsorption structure was observed by the scanning tunneling microscopy (STM) and the effect of electron irradiation was studied by electron injection from the STM tip.The NO species on the atop site can be desorbed by the electron irradiation from the STM tip, while the NO species on the fcc hollow site is suggested to be dissociated by the electron irradiation above 15 eV. The STM observation after irradiation revealed many small corrugation, which is suggested to be the dissociated products of NO. The occupation of the hcp hollow site by NO species, though its adsorption energy is very small, affects the diffusion of NO on the fcc hollow and atop sites. It is suggested that the activity of NO on the P1(111) can be controlled by the occupation of hcp hollow site by NO.