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

9704228布尔昌德获得该奖项，为实现67ZN穆斯堡尔谱仪的新概念提供了部分支持，该仪器将产生比迄今在材料传输测量中使用标准速度驱动的信噪比大得多(至少是20倍)的信噪比。本概念的新颖特征包括：(A)使用避免源和吸收矩阵之间的任何相对运动的相位调制驱动器，以及(B)对重新发射的辐射进行时间滤波，以区分短寿命(10-12s)的非共振辐射和长寿命(10-5s)的共振辐射，以提高信噪比。特征(A)将通过使用由铝楔组成的旋转轮子来实现，该轮子中断来自源的电子束以调制相对于固定吸收体的能量。功能(A)还将允许感兴趣区域速度扫描，这一选项将允许与寿命较短的穆斯堡尔双亲(67Ga和67Cu)更有效地收集信息。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源的电子束，同时闪烁探测器记录来自吸收体的重新发射的射线和转换电子。在4.2K下，这些特征的实现将通过在液氦杜瓦的交换气柱中支撑轮子来完成。该项目将展示使用新的光谱仪获取锌光谱的巨大成本优势，并将使获得正常浓缩的锌化合物光谱成为可能。这样的实验装置将在基础材料研究领域产生重要影响。对锌基无机化合物在吸收中的高分辨率研究以及铜和镓化合物在发射光谱中的高分辨率研究将有助于解决各种材料中悬而未决的材料科学问题，包括II-VI、III-V和II-IV-V2半导体、铜酸盐超导体、钢的电镀、锌铁氧体、锌尖晶石和锌基酶。

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.