Advanced Undergraduate Laboratory Research Articles

Probing coherent phonons in the advanced undergraduate laboratory

Probing coherent phonons in the advanced undergraduate laboratory

Advanced undergraduate laboratory: exploring isotopic shifts in molecular spectroscopy

Current university physics curricula and pedagogical research lack the study of molecular spectrum and its isotopic effects. In light of this, and considering the simplistic architecture of CN molecules alongside the significance of carbon isotopes in atmospheric cycles and various other disciplines, we have developed an advanced molecular spectroscopy experiment tailored for upper-level undergraduate physics educational courses. Utilizing 12CO2 and 13CO2 as experimental mediums, this study delves into the exploration of molecular energy level transitions and isotopic effects within molecular spectra through the analysis of CN molecular emission spectra. Additionally, simulations of CN molecular energy level transitions were conducted using LIFBASE software, thereby deepening students’ grasp of molecular energy level quantization. This experiment uses molecular spectrum to realize the interpretation of energy level structure and isotope effects, which is groundbreaking and will add experimental reference and expansion to the teaching of atomic physics.

Designer spectrographs for applications in the advanced undergraduate instructional lab

In an advanced undergraduate instructional laboratory, it is often necessary to analyze the spectrum of light emitted from an experimental setup. There are numerous instruments that are used to accomplish this analysis, including spectrometers and spectrographs. In this report, we present 3D-printed, low-budget spectrographs (∼ US $200), which are specifically designed for different applications. For example, one can either observe a visible spectrum over a large range of wavelengths about a desired center wavelength or achieve more precise measurements by choosing a smaller part of the visible spectrum. Our generalized design approach is well within the knowledge base of advanced undergraduate physics majors and can be applied to a wide range of applications within the visible spectrum. To demonstrate the utility of these designer spectrographs, we provide examples of recording multiple doublets in the sodium spectrum (a determination of the fine structure spin-orbit splitting of the 3p energy level) as well as measuring the wavelength differences between the hydrogen and deuterium Balmer alpha lines (a measurement of an isotope shift).

Molecular spectroscopy as a laboratory experiment: Measurement of important parameters of sodium diatomic molecules

We present an inexpensive sodium molecular spectroscopy experiment for use in an advanced undergraduate laboratory course in physics or chemistry. The molecules were excited predominantly from the ground X1Σg+(v″ = 15) state to the B1Πu(v′ = 6) state using a commercially available 532-nm broadband diode laser. The laser-induced molecular fluorescence was measured using a miniature fiber-coupled spectrometer at a resolution of 0.5 nm. The spectral peak assignments were done by comparing the observed spectrum with the calculated Franck–Condon values. Important molecular constants such as fundamental frequency, anharmonicity, bond strength, and dissociation energy of the ground electronic state were determined by using the Birge–Sponer extrapolation method. The presence of highly visible blue glowing molecules along the green laser beam creates an engaging laboratory experience. Emphasis is placed on students developing their understanding of the molecular structure, practicing molecular spectroscopic techniques, and applying knowledge of light–matter interactions to a physical system.

Copper(I)-Catalyzed Kinugasa Reactions in an Undergraduate Organic Chemistry Laboratory

A β-lactam, the core structure unit of clinically important antibiotics such as penicillin and cephalosporin, is one of the most commonly encountered four-membered heterocycles in organic chemistry and is widely used in medicine and biochemistry. The Kinugasa reaction, a copper(I)-catalyzed cycloaddition of a terminal alkyne with a nitrone, is a straightforward and atom economic approach to 2,3-disubstituted β-lactams. This paper describes a comprehensive chemistry experiment involving the Kinugasa reaction in an advanced undergraduate organic chemistry laboratory course. Undergraduate students perform the Kinugasa reaction on the benchtop and isolate and characterize the β-lactam product. An understanding of this named reaction and the connection of organic chemistry with medicinal chemistry are specially emphasized in the class. Several modern chemistry concepts that are missing from traditional organic courses such as β-lactam chemistry, [3 + 2] cycloaddition, atom economy, and the important role of transition metal catalysis in organic reactions are introduced to students in this course.

Heisenberg uncertainty principle: an advanced undergraduate laboratory experiment based on quantum quadrature operators

The Heisenberg uncertainty principle (HUP) plays an important role in quantum mechanics. It is necessary to demonstrate this principle experimentally for undergraduates to understand HUP clearly. In this paper, we originally employ the quantum quadrature operators to demonstrate HUP in undergraduate laboratories. Starting from the quantization of electromagnetic field, we briefly review the definition of quadrature operators and demonstrate HUP via the variances of quadrature operators. And the scheme of HUP demonstration with homodyne detection is introduced. More importantly, we develop a tabletop experimental apparatus for the demonstration of HUP in undergraduate laboratories. Our proposal focuses on the basic quantum mechanics concepts, experimental principles, and instruction as well as experimental techniques. It provides a way to help undergraduates, especially the ones who will go on graduate study in quantum technology in the future, make connections between abstract quantum mechanics concepts and concrete experiments, which makes the concepts better understood.

A simple electronic circuit demonstrating Hopf bifurcation for an advanced undergraduate laboratory

A nonlinear electronic circuit comprising of three nodes with a feedback loop is analyzed. The system has two stable states, a uniform state and a sinusoidal oscillating state, and it transitions from one to another by means of a Hopf bifurcation. The stability of this system is analyzed with nonlinear equations derived from a repressilator-like transistor circuit. The apparatus is simple and inexpensive, and the experiment demonstrates aspects of nonlinear dynamical systems in an advanced undergraduate laboratory setting.

Novel design of phase demodulation scheme for fiber optic interferometric sensors in the advanced undergraduate laboratory

Phase modulation depth (PMD) is crucial for the phase demodulation scheme of fiber optic interferometric sensors. The novel design of phase generated carrier differential-cross-multiplying (PGC-DCM) demodulation schemes allows undergraduates to understand the operation principle of the sensors and explore the connection between the PMD and the system performance. The system mainly consists of a laser, a fiber Michelson interferometer (FMI), a data acquisition card and a host computer. The simulation signal is first applied on the sensing arm of the FMI by a piezoelectric transducer and induces the phase difference shift between the two arms. Next the signal-to-noise ratios (SNRs) of the demodulated signals from the PGC-DCM algorithms under different PMD values are tested and an optimum PMD value is found. Thus, a proportion integral differential (PID) module is designed and integrated with the demodulation algorithm to calibrate the PMD to the optimum value. An ellipse fitting algorithm (EFA) is used to estimate the real-time PMD of the system that is then fed into the PID module. The amplitude of the laser modulation signal is controlled by the PID module, which is proportional to the PMD. Moreover, the response linearity, dynamic range, total harmonic distortion and phase resolution of the system are investigated.

Teaching an advanced undergraduate acoustics laboratory without a laboratory: Course developments enabling teaching during the COVID-19 pandemic.

This paper describes ongoing developments to an advanced laboratory course at Kettering University, which is targeted to students in engineering and engineering physics and emphasizes theoretical, computational, and experimental components in the context of airborne acoustics and modal testing [cf. D. A. Russell and D. O. Ludwigsen, J. Acoust. Soc. Am. 131, 2515-2524 (2012)]. These developments have included a transition to electronic laboratory notebooks and cloud-based computing resources, incorporation of updated hardware and software, and creation and testing of a multiple-choice assessment instrument for the course. When Kettering University suddenly shifted to exclusively remote teaching in March 2020 due to the COVID-19 pandemic, many of these changes proved to be essential for enabling rapid adaptation to a situation in which a laboratory was not available for the course. Laboratory activities were rewritten by crowdsourcing archived data, videos were incorporated to illustrate dynamic phenomena, and computer simulations were used to retain student interactivity. The comparison of multiple measures, including the assessment instrument, team-based grades on project papers, and individual grades on final exams, indicates that most students were successful at learning the course material and adapting to work on team-based projects in the midst of challenging remote learning conditions.

Determination of density profile by using the refractive index in a linearly salt-stratified fluid: An experiment for an advanced undergraduate laboratory

This paper describes a low-cost laboratory experiment designed to demonstrate the applicability of the refractive index to study stratification in fluids. The laser refractography method was applied to a linearly vertical density profile of a salt (NaCl) stratified water column. Next, an image processing procedure was performed, consisting of the binarization and edge detection of the laser beam and its subsequent second-order polynomial best fit. Quantitatively, the whole-field results compared well with the respective measured density profiles. This method allows one to obtain quantitative measurements of density profiles in stratified fluids with good accuracy, making it a suitable experimental method for laboratory demonstrations on fluids.

Integration of Interactive Laboratory Videos into Teaching Upper-Undergraduate Chemical Laboratory Techniques

Students in advanced undergraduate chemistry laboratories are required to undertake a wide range of complex and multistep syntheses and analytical procedures, and prospective employers of chemistry graduates seek students with proven skills in these areas. Our approach has been to use video resources which are made available to students both ahead of, and during, their laboratory classes to assist with preparation and provide just-in-time self-help during the laboratory. In this study we evaluate the implementation of a user-focused strategy to improve students’ laboratory skills and use a three-stage model, forethought, performance, and self-reflection, to assess the impact and effectiveness of these resources to complement the traditional laboratory teaching resources of laboratory manuals and laboratory teaching staff (demonstrators). Students demonstrated autonomous learning by engaging with the laboratory videos using both active and passive learning approaches. The benefits of our approach are especially evident for students who have English as a second language and students who identify with different learning preferences. Increased student grades and more effective staff-student supervision time requirements are evident across both third-year undergraduate chemistry courses in which these videos were implemented.

You have the power to change the world through chemistry advocacy

Kevin Kuhn, chair of the Committee on Chemistry and Public Affairs, invited committee member Heidi Vollmer-Snarr to author this comment as an example of how ACS members are using the society’s advocacy tools to advance science. Vollmer-Snarr is director of advanced undergraduate laboratories at Harvard University. This past year, science has emerged more prominently than ever, with scientists developing vaccines in record time and advising officials on how to rebound from lockdowns and closures. However, because most of our elected officials are not trained scientists, they need our help as they try to rebuild. Last month, President Joe Biden, Vice President Kamala Harris, and the 117th Congress got to work—individuals who are eager to roll out their varying legislative priorities. They are entering one of the most challenging moments for the US—thousands of Americans die every day from the COVID-19 pandemic, millions of children are struggling in their education because

Green Fischer Indole Synthesis Using a Steroidal Ketone in a Conductively Heated Sealed-Vessel Reactor for the Advanced Undergraduate Laboratory

Highly efficient microwave-assisted organic synthesis is now commonplace in both industry and academia. Recently, a conductively heated sealed-vessel reactor was introduced that acts very similarly to a microwave reactor and is more affordable. Application of such reactors in teaching laboratories is advantageous because of the restricted window of time available to perform experiments and because it avoids long reaction times that are unpopular with students. These reactors thus allow reactions that were previously considered impractical for the teaching laboratory, such as the Fischer indole synthesis, to now be very feasible. We designed a clean and efficient Fischer indole synthesis to introduce advanced undergraduate students to this important method in heterocycle synthesis, which has been highly under-represented in the curriculum. It also introduces it in the context of a more complex ketone of biological relevance (a steroid). This laboratory exercise can be used to teach about Green Chemistry Principles, product analysis (TLC, NMR, MS, UV–vis), and a complex multistep mechanism. It can also act as a starting point to teach terpenoid biosynthesis, some key concepts in medicinal chemistry such as pharmacophores and pro-drugs, and even to open discussions on the societal impacts of steroids.

Fluorescence lifetime measurements with simple correction for instrument temporal response in the advanced undergraduate laboratory

Observation of time-dependent luminescence from excited states with a wide range of lifetimes allows students to explore the connection between selection rules and transition rates. It is fairly simple to measure microsecond and longer lifetimes with equipment common to undergraduate programs, because the instrument response time of even modest bandwidth systems is insignificant on microsecond and longer time scales. The measurement of nanosecond lifetimes, however, is more challenging, because the instrument response time is comparable to the lifetimes being measured. In this case, the instrument temporal response must be deconvolved from the observed luminescence signals in order to extract the actual excited state lifetime. We describe a method for measuring nanosecond fluorescence lifetimes in the advanced undergraduate laboratory that uses real-time analog luminescence signals instead of traditional photon counting techniques. The detection electronics of this method are fairly simple, consisting of an oscilloscope monitoring the time-dependent output of an inexpensive silicon photomultiplier. We introduce a simple and transparent method for students to characterize the instrument response and deconvolve it from the observed luminescence signals, yielding measured nanosecond fluorescence lifetimes in good agreement with the corresponding literature values obtained by time-correlated single photon counting. The limitations of silicon photomultipliers for this method of measuring nanosecond lifetimes are discussed in detail. Application of this treatment to decay processes that are not single exponential is also discussed.

Exploring delay dynamics with a programmable electronic delay circuit

Delay dynamics occur in a wide variety of natural and man-made systems. Even simple delay systems can generate complex dynamics whose exploration is rewarding. To allow such exploration as part of advanced undergraduate laboratory courses and be able to utilize systems that operate at convenient timescales, it is necessary to delay analog signals by several milliseconds. In this paper, we describe an implementation of a programmable digital circuit capable of delaying DC-coupled analog signals up to 262 ms at a 1 MHz sampling rate. The initial history of the system may also be arbitrarily programmed, enabling the study of transient behavior. As an application, we discuss the use of this programmable delay in a feedback circuit that produces period-four triangular solutions, in complete agreement with theoretical predictions.

Development and Evaluation of Paper-Based Devices for Iron(III) Determination in an Advanced Undergraduate Laboratory

We describe a paper-based microfluidic device for iron(III) assay in an applied instrumental analysis laboratory. Simple and convenient devices were fabricated by the students using patterning of f...

Terrella for advanced undergraduate laboratory

A terrella developed for the undergraduate Advanced Laboratory course in the University of Wisconsin-Madison Physics Department is described. Our terrella consists of a permanent magnet, mounted on a pedestal in a vacuum chamber, surrounded by electrodes that may be biased in various ways. The system can confine a plasma, which may, in some ways, be considered as a toy model of the plasma confined in the Earth's magnetosphere. Our axisymmetric plasma forms in a region where the magnitude of the magnetic field B is 14 G ≤B≤ 550 G; for typical operation, the neutral gas pressure is p∼10−4 Torr. The plasma is created by thermionic emission from a hot filament. Available diagnostics are a swept Langmuir probe, a spectroscopic fiber and visible-wavelength spectrometer, and visible imaging. In two four-hour laboratory sessions, students are guided through vacuum pumpdown, connection of electrical circuits, establishment of plasma, acquisition of data, analysis of data, and critique of data. In this paper, we present student measurements of radial profiles of electron temperature Te and density ne as well as imaging of mirror trapping and ∇B drift and curvature drift. We conclude by outlining some opportunities for additional terrella-based student experiments.

An autocollimator with sub-microradian sensitivity

We present a simple autocollimator with sub-microradian sensitivity. To demonstrate the capabilities of our autocollimator, we study the simple harmonic motion of a cantilever beam and apply an external force to affect the cantilever's resonant frequency in the context of dynamic force microscopy. Our setup is ideal for the advanced undergraduate instructional laboratory and allows a variety of high-precision, tabletop experiments.

Design, Implementation, and Evaluation of Paper-Based Devices for the Detection of Acetaminophen and Phenacetin in an Advanced Undergraduate Laboratory

Reported herein is a multidisciplinary experiment for senior-level undergraduate teaching laboratories in the synthesis of the analytes acetaminophen and phenacetin; the fabrication of paper-based devices, using eyeliner, acrylic spray paint, or wax-printing, for sensing of those analytes; and the use of the newly fabricated devices for successful qualitative and quantitative analyte detection. This experiment includes elements of organic, analytical, and materials chemistry, as well as device engineering, and provides a strong pedagogical experience for the undergraduate student participants. The experiment was tested over two years in the Advanced Organic Laboratory, and 90% of students over the two years successfully completed all experimental objectives. The modular nature of the reported experiments and inexpensive costs of materials and instrumentation significantly enhance the practical applicability of this experiment and the likelihood of widespread adaptation.

Fabrication and characterization of a microfluidic flow cytometer for the advanced undergraduate laboratory

Microfluidic devices can be used to explore a vast range of phenomena in biophysics and soft-matter physics. While the popularity of these devices is in part driven by the ease of soft-lithography, most research labs still depend upon expensive, clean-room fabrication of photoresist molds, which can make this technique inaccessible to the undergraduate laboratory. However, there are much simpler, if coarser, approaches to designing molds that are capable of producing surprisingly complicated devices. Here, we detail the fabrication and characterization of a microfluidic device for flow cytometry or particle sorting on a chip. Our device is a layered polydimethylsiloxane chip that uses a series of Quake valves to sort. The molds were fabricated on equipment accessible to most undergraduate labs. The techniques and physics we discuss in this manuscript can be employed to create an almost endless variety of devices for learning about complex fluid mechanics, mesoscopic, soft-matter, and biological physics.