Realization of Platinum Nitride and Study of reaction with gas molecules

本研究的目的是实现用常规方法无法构建的氮化铂。当吸附在Pt（111）上的一氧化氮（NO）受到紫外（UV）光或电子照射时，它被认为是解离的。本文研究了NO在Pt（111）上的吸附和脱附，以及在紫外光和电子辐照下的脱附/解离，结果表明，尽管Pt（111）具有催化活性，但NO在Pt（111）上不能解离，只能在低温下吸附，加热脱附。当NO覆盖度增加时，NO首先吸附在3重fcc中空位上，然后吸附在1重atop位上，最后吸附在3重hcp中空位上。由热脱附谱（TDS）中的脱附峰获得吸附能。利用NO同位素14 NO和15 NO对吸附在不同位置上的NO物种之间的相互作用进行了精确的研究。通过扫描隧道显微镜（STM）观察了吸附结构，并通过STM针尖的电子注入研究了电子辐照对NO吸附的影响，结果表明，在STM针尖的电子辐照下，顶部的NO物种可以脱附，而在fcc中空位置的NO物种则被高于15 eV的电子辐照解离.照射后的STM观察发现许多小的NO，这被认为是NO的解离产物。NO物种的hcp中空位点的占领，虽然它的吸附能很小，影响NO在fcc中空和顶部网站上的扩散。提示NO在P1（111）上的活性可能是通过占据hcp中空位点来控制的。

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.