By combining the rapid development in direct digital synthesis circuitry and Field Programmable Gate Arrays (FPGAs) coupled to fast A/D samplers, it is possible to construct high performance chirped pulse microwave spectrometers suitable for gas-phase rotational spectroscopy experiments in undergraduate physical chemistry labs as well as graduate level research. The technology is highly tailorable, and sufficiently robust that extensive experimentation is feasible in the teaching environment. The time domain nature of the experiment has strong ties to concepts in Nuclear Magnetic Resonance (NMR) widely discussed in undergraduate curricula, and the software environment for the instrument control and spectral assignment can be integrated with ab initio quantum chemistry predictions of molecular structure and dynamics.

r0pt Figure Research, design, construction, and operation of a portable mixed Raman and Fluorescence type spectrometer implemented by the Missouri University of Science and Technology’s Mars Rover Design Team will be presented. This spectrometer has been built for the team’s annual competition. The spectrometer, completely built by undergraduates, is designed to use a 50 mW, 532 nm constant waveform laser to probe a sample of soil to find bacteria or bio-markers. However, initial tests of the spectrometer were carried out in a laboratory environment making the spectrometer also suitable for simple undergraduate physical chemistry or chemical physics laboratory experiments. The final cost of the device is roughly $2100, weighs 1.4 kg, and is 22.9 cm x 22.6 cm in size. Integrating the spectrometer with a computer database, results from the competition, complications of fitting mixed Raman-Fluorescence spectra, and future ideas/improvements will also be discussed.

Electronic spectroscopy of molecular iodine vapor has long been studied in undergraduate physical chemistry teaching laboratories, but the effectiveness of emission work has typically been limited by availability of instrumentation. This talk shows how to make inexpensive green diode-pumped solid-state (DPSS) lasers easily tunable for efficient, selective excitation of I₂. Miniature fiber-optic spectrometers then enable rotationally resolved fluorescence spectroscopy up to v" = 42 near 900 nm with acquisition times of less than one minute. DPSS lasers are also versatile excitation sources for vibrational Raman spectroscopy, which is another common exercise that has been limited by lack of proper instrumentation in the teaching laboratory. This talk shows how to construct a simple accessory for commercial fluorimeters to record vibrational Raman spectra and depolarization ratios for CCl₄ and C₂Cl₄ as part of a lab exercise featuring molecular symmetry.

r0pt Figure A windows based, mouse-event driven software program that acts a graphical user interface to Pickett's fitting programs has been created and improved. The program, SpecFitter, is aimed at walking users through the process of assigning pure rotational spectra. Rotational spectra, in XY format, may be viewed and inspected and the user is provided with tools for observing and recording repeating, similar patterns of transitions. The structure of these patterns is interpreted into "guesses" at rotational constants which the user may then use to predict a spectrum. Observed transition frequencies may then be assigned quantum number transitions and appended to the .lin file through mouse clicks. Although the thrust of this project is to develop a users ability to assign spectra without knowing the molecule producing the spectra the program can also read in and display calculated structures of target molecules produced by the Gaussian03/09 software, or alternatively the user can draw their own structures. Structures can be edited allowing users to observe the relationship between molecular structure and (i) the direction of dipole moment components and (ii) the relationships between structure and rotational constants. Users may also easily predict spectra from the molecules structure and further relate rotational constants to observed spectra. Students in CHEM 3510 at Purchase College have been vital in developing the software.

A study of the vibrational spectra of cis- and trans-1,2-dichloroethylene provides an excellent way for undergraduates to gain experience with the application of group theory in the physical chemistry laboratory. Although the group vibrations are similar for these two molecules, the selection rules for infrared (IR) and Raman spectra differ significantly. Most of the transitions for the fundamentals of the cis isomer of C_2v symmetry are both IR and Raman active. Mutual exclusion for the vibrational transitions applies to the centrosymmetric trans isomer of C_2h symmetry. Thus, half the transitions for the trans isomer are IR active and half are Raman active. The two isomers are volatile enough that gas-phase IR spectra can be recorded at room temperature. Band shapes in gas-phase IR spectra provide additional evidence for assignments of fundamentals. The two isomers are small enough that good quality quantum chemical calculations of harmonic frequencies can be done by students with commercial software.

Hydrocarbons, especially large ones such as isooctane, have infrared active species that give insight into combustion stoichiometry and temperature. Here a Fourier-transform infrared spectrometer is utilized to study the IR active species for a number of stociometric conditions for several fuels including isooctane, kerosene, and ethanol. Special attention is given to intermediate species in different flame regions.

The use of chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy as a tool for training undergraduates will be discussed. Coker College’s inexpensive, versatile CP-FTMW spectrometer has been applied both in the undergraduate teaching laboratory and the undergraduate research laboratory. In both cases, the education of the students is a central priority of the project. The study of 3-iodopyridine, a project recently completed by Coker undergraduate students, will be discussed. Details of the Coker CP-FTMW spectrometer will also be presented.

A new experiment appropriate for both general chemistry and physical chemistry students will be described. The experiment utilizes "pocket size" USB spectrometers (operating in the UV/vis region) coupled with fiber optic cables to record a solar spectrum. A further extension of the experiment involves recording spectra of a light bulb at several voltages (and thus resistances). Using provided software, students can fit black body distributions to their obtained spectra. The software will display the acquired spectrum, a simulation based on their guess temperature, a simulation based on their fit, and OMC² for both. Students can then compare their results to the known temperature of the sun and the known temperature vs resistance curve of tungsten.

The CO₂ asymmetric stretch fundamental band near 4.3 μm is one of the strongest infrared absorption transitions of all small molecules. This band is an undesired interference in most infrared spectra, but it also serves as a potential choice for a vibration-rotation analysis experiment in the physical chemistry teaching laboratory. Due to the strength of this band and the 1.1% natural abundance of carbon-13, the asymmetric stretch fundamental band of ¹³CO₂ is readily observable in a typical ambient air background spectrum and is shifted sufficiently from the stronger ¹²CO₂ fundamental such that the ¹³CO₂ P-branch lines are almost completely free of interferences and are easily assigned. All of the ¹³CO₂ R-branch lines appear within the ¹²CO₂ P-branch, which creates assignment challenges. Students in our program have analyzed the ¹³CO₂ fundamental asymmetric stretch band over a two-year period. Analyses of the P-branch line positions enabled the prediction of additional R-branch line positions, which guided line identification and measurements in the ¹³CO₂ R-branch. C=O bond lengths determined from analyses of the ¹³CO₂ spectra improved when R-branch lines were added to the initial P-branch data sets. Spectral appearance, analyses and results will be presented for spectra obtained at 0.5 cm⁻¹ resolution and at 0.125 cm⁻¹ resolution. The challenge of predicting and finding the ¹³CO₂ R-branch lines among other interfering lines adds an element of realism to this experiment that is not found in many student experiments of this type.

Given today's technological age, it has become crucial to be able to reach the student in a more "tech-savvy" way than traditional classroom methods afford. Given this, there are already a vast range of software packages available to the molecular spectroscopist that can easily be introduced to the classroom with success. This talk will highlight taking a few of these tools (Gaussian09, SPFIT/SPCAT, the AABS Package, LabView^TM, etc.) and implementing them in the classroom to teach subjects such as Quantum Mechanics and Thermodynamics as well as to aid in the linkage between these subjects. Examples of project implementation on both undergraduate and graduate level students will be presented with a discussion on the successes and failures of such attempts.