CRIF:ID-Design and Construction of a 1 to 10 GHz Pulsed-beam, Fourier-Transform Spectrometer

利用化学研究仪器和设施仪器开发计划的这一奖项，亚利桑那大学的Stephen Kukolich教授将开发一种脉冲束傅里叶变换微波光谱仪，用于测量过渡金属络合物，氢键络合物和其他分子的旋转跃迁频率在微波光谱的1至10 GHz区域。与以前的脉冲束FT微波光谱仪不同，这将允许测量低于4 GHz的频率，这对大分子非常重要。大分子具有复杂的旋转光谱，用于源自高旋转激发态（高J态）的跃迁，使得这种光谱难以分配。从大分子的旋转冷态（低J态）的转变被简化和不那么拥挤，但获得这样的转变一直是有限的，因为这些转变中的一些落在技术上无法达到的光谱区域低于4 GHz。拟议的仪器将能够进入这一区域，从而能够分配旋转光谱和确定大分子的分子几何形状。该光谱仪将能够进行结构和四极耦合测量：1）双核过渡金属配合物，2）选择用于模拟生物系统中的相互作用的较大氢键配合物，例如碱基对识别和蛋白质折叠，3）具有较大配体的过渡金属络合物，和4）其它生物学感兴趣的分子。拟议的研究项目将在亚利桑那大学的研究生和本科生的合作和参与下进行。参与研究项目将使学生获得化学，量子力学，计算机技术，微波电子学，光谱学和物理测量的基础知识和经验。

With this award from the Chemistry Research Instrumentation and Facilities Instrument Development program, Professor Stephen Kukolich of the University of Arizona will develop a pulsed-beam, Fourier-transform microwave spectrometer to measure rotational transition frequencies for transition metal complexes, hydrogen-bonded complexes, and other molecules in the 1 to 10 GHz region of the microwave spectrum. Unlike previous pulsed-beam FT microwave spectrometers, this will allow measurement of frequencies below 4 GHz, which is very important for large molecules. Large molecules have complicated rotational spectra for transitions originating from high rotationally excited states (high J states), making such spectra difficult to assign. Transitions from rotationally cold states (low J states) of large molecules are simplified and less congested, but access to such transitions has been limited, since some of these transitions fall in the technologically inaccessible spectral region below 4 GHz. The proposed instrument would be able to access this region, and thus enable assignment of rotational spectra and determination of molecular geometries of large molecules.The spectrometer will enable structure and quadrupole coupling measurements for: 1) dinuclear transition metal complexes, 2) larger hydrogen bonded complexes chosen to model interactions in biological systems, such as base-pair recognition and protein folding, 3) transition metal complexes with larger ligands, and 4) other molecules of biological interest. The proposed research projects will be carried out with collaboration and participation of graduate and undergraduate students at The University of Arizona. Participation in the research projects will allow the students to gain experience and knowledge in the fundamentals of chemistry, quantum mechanics, computer technology, microwave electronics, spectroscopy, and making physical measurements.