Far Infrared Fourier Transform Spectrometer for Undergraduate Physics Experiments

物理学(13)原子在分子或晶格中的运动构成了多原子系统最基本的物理现象之一，但很少有本科物理课程包括振动性质的实验研究。现代光谱仪可以使用傅里叶变换方法测量远红外频率，非常适合训练有素的本科生操作。在这个项目中，学生们将在本科物理实验中使用远红外(FIR)傅里叶变换(FT)光谱仪，以便他们熟悉这项重要的技术，并看到基本的物理概念被带入生活。光谱仪被用来加强现代物理课程的实验室部分，全面改革实验凝聚态物理课程，扩大师生研究项目的数量，并与化学系进行合作。学生们正在从研究气相中双原子分子的振动，到嵌入在分子固体中的大富勒烯笼子的振动，再到简单离子晶格中的声子。第二年的现代物理实验室正在纳入一个关于气相HCl的旋转和振动的经典实验的扩展版本。该仪器的远红外和中红外双重功能使学生能够在低频率下观察纯分子旋转的激发，并在中红外区域的振动上再次识别它们为精细结构。FIR振动光谱学的两个实验正在对高级实验凝聚态物理课程进行重大改革。第一个，改编自研究文献和布达佩斯大学和布达佩斯工业大学学生的本科工作，展示了对称性在决定原始和光聚合C60的振动性质方面的核心作用。第二，基于里德学院最近进行的一项实验，将简单的一维晶格动力学计算与实际物理系统中光学声子模的观测联系起来。这个项目的另一个目标是利用这个机会接触到科尔比大学前所未有的数量的女物理专业学生，2000年秋季现代物理课程的预注册号码表明了这一点。通过提供特别的实验物理本科课程，我们希望促进这些年轻女性的职业生涯，激励她们成为其他人的榜样，并在该项目中保持足够多的女性。对该项目的评价将具体考虑其对女学生以及对一般学生学习的影响。学生将在本科生会议上传播研究成果，并酌情在教育或研究期刊上发表。

Physics (13) The motions of atoms within a molecule or a crystal lattice constitute one of the most fundamental physical phenomena of multi-atom systems, yet few undergraduate physics curricula include experimental studies of vibrational properties. Modern spectrometers can measure frequencies into the far infrared using the Fourier Transform method and are well suited to operation by trained undergraduates. In this project, students are using a far infrared (FIR) Fourier Transform (FT) spectrometer in undergraduate physics experiments, so that they will become familiar with this important technique and see basic physics concepts brought to life. The spectrometer is being used to enhance the laboratory component of the Modern Physics course, to overhaul the Experimental Condensed Matter Physics course, to expand the number of student-faculty research projects, and to engage in collaborations with the Chemistry Department. Students are progressing from studying vibrations of diatomic molecules in the gas phase, to vibrations of large fullerene cages imbedded in a molecular solid, to phonons in simple ionic crystalline lattices. The second year Modern Physics laboratory is incorporating an expanded version of a classic experiment in rotations and vibrations of gas phase HCl. The dual far and middle infrared capability of the instrument allows students to observe excitations of pure molecular rotations at low frequency, and recognize them again as fine structure on top of vibrations in the middle infrared region. Two experiments in FIR vibrational spectroscopy are effecting a major revamping of the advanced Experimental Condensed Matter Physics course. The first, adapted from the research literature and the undergraduate work of students at the L. Eotvos University and the Technical University of Budapest, demonstrates the central role of symmetry in determining vibrational properties of pristine and photo-polymerized c60. The second, based on an experiment that was recently implemented at Reed College, connects a simple 1D lattice dynamics calculation to the observation of optical phonon modes in a real physical system. Another goal of this project to take advantage of an opportunity to reach an unprecedented number of women physics majors at Colby, as indicated by pre-registration numbers for the fall 2000 Modern Physics course. By providing an exceptional undergraduate program of experimental physics, we hope to further the careers of these young women, inspire them to become role models for others, and maintain a critical mass of women in the program. Evaluations of the project will consider specifically their impact on female students as well as on student learning in general. Students will disseminate the results at conferences for undergraduates, and in education or research journals, as appropriate for the work.