Integrating Single Crystal X-Ray Diffraction in the Undergraduate Curriculum

Powder diffraction is one of the most widely used analytical techniques for characterizing solid state materials. It can be used for phase or polymorph identification, quantitative analysis, cell parameter determination or even full crystal structure analysis using the powerful Rietveld refinement method.As with much of modern crystallography, the software used for Rietveld refinement is frequently treated as a "black box" that produces often-poorly-understood outputs. This paper shows how it is possible for students to perform a full Rietveld refinement against experimental powder diffraction data from scratch using a simple spreadsheet like Excel. It starts by reviewing the basic ideas of leastsquares fitting a straight line, develops these into fitting simple functions to peaks in simulated experimental data, then combines these ideas with crystallographic equations to enable Rietveld refinement of the structure of an inorganic material (rutile, TiO2). At each stage students can selflearn different fundamental aspects and pitfalls of data analysis that are widely re-applicable. The ideas can be taught as an online learning exercise, or could be incorporated in a laboratory class where students collect and analyze their own experimental data.

Section: Diffraction Fundamentalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure Analysis from Powder Diffraction Data: Rietveld Refinement in Excel

Evans

2020

“…In 1956, X-ray diffraction studies were first demonstrated as a valuable technique for characterizing essential oils and their derivatives . X-ray powder diffraction data on a variety of semicarbazone carbonyl type compounds including carvone were published by Meranger et al Recently, the incorporation of single-crystal X-ray diffraction into the undergraduate chemistry curriculum has since proven itself in terms of the pedagogical value and benefits to students. − Despite the obvious benefits, the technique has not been adopted widely, primarily due to the expense of installing and maintaining the instrumentation needed. This experiment could become a virtual reality in the absence of equipment (see instructor Supporting Information).…”

Section: Introductionmentioning

confidence: 99%

Combination of X-ray Diffraction and Specific Rotation to Unequivocally Characterize Carvone Semicarbazone Derivatives

Dolhun

Müller

2020

Single-crystal X-ray structures, melting points, and students’ specific rotation results on carvone semicarbazone derivatives are presented with experimental details. Critical parameters are identified to ensure the success of the experiment. Procedures developed here were tested in a laboratory course, consisting of approximately 70 students over three semesters. This experiment teaches undergraduate students important new instrumental methodology for characterizing a sample, allowing students to gain skills from hands-on experience using modern analytical instrumentation, and analyzing data to achieve a conclusion.

“…The established model for practical training at the University of Southampton places first and second year undergraduates into teaching laboratories, following prescribed methods in large group sizes and gaining foundational experience in common analytical techniques, e.g., infrared (IR) and precollected nuclear magnetic resonance (NMR) spectra. However, access to advanced characterization techniques, specifically hands-on X-ray crystallography, − at the undergraduate level is restricted, mainly due large to group sizes and scarce resources. These techniques would only be (partly) experienced in the latter stages of a degree if an embedded research project were undertaken.…”

Section: Introductionmentioning

confidence: 99%

Conducting Reflective, Hands-On Research with Advanced Characterization Instruments: A High-Level Undergraduate Practical Exploring Solid-State Polymorphism

Coles

Mapp

2015

An undergraduate practical exercise has been designed to provide hands-on, instrument-based experience of advanced characterization techniques. A research experience approach is taken, centered around the concept of solid-state polymorphism, which requires a detailed knowledge of molecular and crystal structure to be gained by advanced analytical techniques normally considered as the preserve of a research facility. Powder and single crystal diffraction techniques are primarily required and implemented via the unique approach of the students themselves using benchtop instruments dedicated to teaching, as opposed to more complex and difficult to access research instruments. Furthermore, the manual instructions for performing the practical are delivered via an adapted Electronic Laboratory Notebook system where, for each specific aspect of the practical, students note their intentions, actions, observations, and inferences. Assessors can access the notebooks and provide targeted online feedback for each individual section. Evaluation of the approach is based on interviews and surveys with the first cohort of 65 students that performed the practical.