Investigation on the quantum motion of H on transition metal surfaces

H在过渡金属表面的量子运动研究

基本信息

批准号：
09640601
负责人：
TAKAGI Noriaki
金额：
$ 2.37万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

H is the lightest element and thus the motion of H is often described by not classical but quantu mechanics, As for H on metal surfaces, the activation energy of for surface diffusion is almost tr same order as the vibrational energy of H.Therefore, H in the vibrational excited states can be expected to be quantum-mechanically delocalized and thus the vibrational level is described by atomic band model just like an electron in the periodical potential well (Bloch state). The theo ret calculation for H on Ni surfaces indicates that the vibrational excited levels have widths of a few. several tens meV.We have investigated the vibrational spectra of Hon Pd(110), Ni(111) and Rh(111) at 90 K by using high resolution electron energy loss spectroscopy (HREELS). For H on Pd(110) surface, three losses are observed at 87-89, 96-100 and 121-122 meV for low H coverage regions. The coverage dependences of the 87-89 and 96-100 meV losses are compar with the model calculation based on the quantum delocalization of H.The agreement between experimental and theoretical results is reasonably good, and hence it is concluded that H in the vibrational state is quantum-mechanically delocalized on Pd(110). The vibrational spectra for H Ni(111) has been investigated with the energy resolution of 1-2 meV.For the (2x2)-2H phase, asymmetric stretching modes for H in hcp and fcc sites are observed at 90 and 96 meV.The wi of these losses are narrow (about 2 meV). As the H coverage is decreased, weak but broad structure ranging from 60 to 110 meV is observed which may be related to the quantum motior H.For H on Rh(111), EELS spectra do not show any evidence of the quantum delocalization of H However, energy resolution is not so good (7-8 meV) and thus this system should be reinvestigated with much high energy resolution.

h是最轻的元素，因此H的运动通常不是经典的，而是量子力学的描述，例如在金属表面上的H中，表面扩散的激活能与H的振动能量几乎相同。因此，振动态中的H可以预期被量子化的量子化和振动级别的振动级别，从而由振动级别进行了振动，从而由eLibrational pomential proment targity proment and priblational proment and Orch priptation-equarity模型（均与一个定期）模型（同时是一个定期）。 Ni表面上H的Theo RET计算表明振动激发水平的宽度为少数。我们使用高分辨率电子损失光谱（HREELS）研究了几十MeV。我们研究了Hon PD（110），Ni（111）和RH（111）的振动光谱。对于PD（110）表面的H，对于低H覆盖区域，在87-89、96-100和121-122 MEV时观察到三个损失。 87-89和96-100 MEV损失的覆盖率依赖性与基于H的量子定位的模型计算进行了比较。实验和理论结果之间的一致性相当好，因此得出结论，振动状态的H在PD上是量子机制划定的（110）。已经研究了H Ni（111）的振动光谱（111）的能量分辨率为1-2 MeV.（2x2）-2h相，HCP中H和FCC位点的H HCP的不对称拉伸模式在90和96 MEV处观察到这些损失的WI。随着H覆盖范围的下降，观察到弱但广泛的结构从60到110 MeV不等，这可能与H. for H. for H.在RH（111）上有关，EELS光谱没有显示出H的任何证据表明H的量子定位h但是，能量分辨率的量子分辨率并不是很好（7-8 MeV），因此该系统应与许多高能量分辨出许多高能量。