Development of a Novel 67ZN Mossbauer Spectrometer for Basic Materials Research

该奖项为实施67Zn M斯堡尔光谱仪的新概念提供了部分支持，该光谱仪将产生比迄今为止使用标准速度驱动器在材料传输测量中可能产生的更大（至少20倍）的信噪比。本概念的新特点包括：(a)使用相位调制驱动，避免源和吸收矩阵之间的任何相对运动；(b)对重发射辐射进行时间滤波，以区分短寿命（10-12s）的非谐振辐射和长寿命（10-5s）的谐振辐射，以提高信噪比。特征(a)将通过使用由Al楔组成的旋转轮来实现，该旋转轮中断来自源的光束，以相对于固定吸收器调制能量。特征(a)还将允许感兴趣区域速度扫描，这一选项将允许更有效地收集短寿命M - ssbauer亲本（67Ga和67Cu）的信息。特征(b)将通过使用带有窄缝的快门轮来实现，该快门轮将阻挡来自光源的光束，而闪烁探测器将记录来自吸收器的再发射射线和转换电子。通过在液氦杜瓦瓶的交换气柱中支撑轮子，在4.2K下实现这些功能。该项目将证明使用新光谱仪获得锌光谱的巨大成本优势，并应使获得正常富集锌化合物的光谱成为可能。这样的实验设备将在基础材料研究领域产生重要的影响。吸收光谱中Zn基无机化合物的高分辨率研究以及发射光谱中Cu和ga基化合物的高分辨率研究将允许解决各种材料中的突出材料科学问题，包括II-VI， III-V和II-IV-V2半导体，铜超导体，钢的镀锌，Zn-铁氧体，Zn尖晶石和锌基酶。

9704228 Boolchand This award provides partial support for implementing a new concept of a 67Zn M ssbauer spectrometer which will yield significantly larger (at least a factor of 20) signal to noise ratios than hitherto possible using standard velocity drives in transmission measurements of materials. The novel features of the present concept includes (a) use of a phase modulation drive which avoids any relative motion between source and absorber matrix, and (b) time-filter the re-emitted radiation to discriminate the short lived (10-12s) non-resonant radiation from the long-lived (10-5s) resonant one to enhance the signal to noise ratio. Feature (a) will be implemented by using a rotating wheel consisting of Al wedges which interrupt the -beam from a source to modulate the energy with respect to a stationary absorber. Feature (a) will also permit region of interest velocity scans, an option that will permit a more efficient collection of information with the short-lived M ssbauer parents (67Ga and 67Cu). Feature (b) will be implemented by using a shutter wheel with narrow slits, that will block the -beam from the source while a scintillation detector registers the re- emitted -rays and conversion electrons from the absorber. Implementation of these features at 4.2K will be done by supporting the wheels in an exchange gas column of a liquid Helium dewar. The project will demonstrate the enormous cost advantage of obtaining Zn spectra using the new spectrometer and should make possible obtaining spectra of Zn compounds of normal enrichment. Such an experimental facility will have important consequences in the field of basic materials research. High resolution studies of Zn based inorganic compounds in absorption and Cu- and Ga-based compounds in emission spectroscopy will permit addressing outstanding materials science issues in a wide variety of materials including II-VI, III-V and II-IV-V2 semiconductors, cuprate superconductors, galvanization of steels, Zn-ferrites, Zn-spinels and zinc based enzymes.