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High-resolution depth profiling of surface hydrogen by a resonant nuclear reaction

通过共振核反应对表面氢进行高分辨率深度分析

基本信息

批准号：
04555001
负责人：
MURATA Yoshitada
金额：
$ 13.63万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

A high-resolution depth-profiling method of hydrogen was developed at the 2C beam line of the new tandem-type Van de Graaph accelerator at the Research Center for Nuclear Science and Technology, University of Tokyo, in aimed at the investigation of hydrogen dynamics at surfaces and interfaces.The experiment was performed in a ultra-high vacuum chamber equipped with LEED and quadrupole mass spectrometer. The resonance nuclear reaction of ^1H (^<15>N,alphagamma) ^<12>C of which resonance width is 1.8KeV was applied to dydrogen detection. A ^<15>N^<2+> ion at an energy of 6.385 MeV was generated from tandem-type Van de Graaph accelerator with an energy spread of 5 keV.The gamma-ray emitted as a result of the nuclear reaction with hydrogen was detected by a Bi_4Ge_4O_<12> scintillator. The gamma-ray yield as a function of the incident energy shows the depth profile of H of the sample. Since the energy loss of a ^<15>N^<2+> ion at 6.385 MeV in Pb is 0.23 KeV/*, the depth resolution estimated from the resonance, Instrumental and Doppler widths is about 40 *. Samples we used are metal overlayr on Si (lll) 7_x7-H and Si (lll) 1_x1-H,which were prepared by exposing the Si (lll) clean surface to atomic hydrogen untill saturation at sample temperatures of 300 and 700 K,respectively, H-Au (001), and Olivine/Aqueous Solution Interface. Atomic hydrogen was produced by introducing H_2 gas through tungsten tube heated at 1800K.We demonstrated that this method is very powerful for high-resolution depth profiling of hydrogen at a surface and interfaces below the surface.

在东京大学核科学技术研究中心新型串列式货车de Graaph加速器的2C束线上，建立了一种高分辨率的氢深度剖面测量方法，用于研究表面和界面处的氢动力学，实验在超高真空室中进行，并配备了LEED和四极质谱仪。将共振宽度为1.8KeV的^1H（^<15>N，γ）^<12>C共振核反应应用于氢气探测。在<15>串列式货车de Graaph加速器上产生了能量为6.385 MeV的N^<2+>离子，能散为5 keV<12>。γ射线产额作为入射能量的函数示出了样品的H的深度分布。由于<15>6.385 MeV ~（2+）离子在Pb中的能量损失为0.23 KeV/*，因此由共振宽度、仪器宽度和多普勒宽度估算的深度分辨率约为40 *。我们使用的样品是Si（III）7-x7-H和Si（III）1-x1-H上的金属覆盖层，它们是通过将Si（III）清洁表面暴露于原子氢直到分别在300和700 K的样品温度下饱和而制备的，H-Au（001）和橄榄石/水溶液界面。通过在1800 K下加热的钨管通入H_2气体产生原子氢，证明了这种方法是一种非常有效的高分辨率氢在表面和表面下界面深度分布的方法。