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Tombros Fellows of the CESE: Jennifer Tan

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Description of Jennifer Tan's CESE fellowship project

Fellow Bio:

Jennifer Tan is a 5th year graduate student in chemistry focusing on physical chemistry. The running title of her PhD work is: Interaction of luminescent guest molecules and quantum dots with host media: liquids, molecular solids and polymers. She also has a strong interest in Chemical Education (her career interest is to teach chemistry at a liberal arts college).  She is a teaching assistant for the introductory physical chemistry lab as well as the advanced physical chemistry lab. Jennifer combines her research and teaching interests by creating innovative and challenging laboratory projects for a 400-level chemistry laboratory course from her thesis work. This is how she contributes in the apprenticeship model of instruction which her thesis adviser, Dr. Bratoljub Milosavljevic, uses to prepare graduate students for teaching careers as well as to provide the undergrads with better quality teaching.


To download Jennifer's Fellows Presentation from October 2013, please click here.  

Jennifer Tan's Fellows Proposal:

[ Title ] Maintaining High Level Laboratory Experiences Using an Apprenticeship Model of Instruction

[ Information ]

Courses involved: CHEM 457, CHEM 459W

Project type: Fundamental improvements in 400-level capstone laboratory courses aimed at improving practical lab skills and critical especially for graduating juniors/seniors. Enhancing graduate education by incorporating teaching, lab management, and communication.

Submitting PI:  Jennifer G. Tan, Department of Chemistry, Pennsylvania State University, 

University Park, PA 16802


[ Abstract and learning objectives ]

The teaching mission of the Eberly College of Science at Penn State places high priority on enhancing the undergraduate education experience to train scientifically-minded students that can serve their communities and work effectively as new graduates. Many undergraduate laboratory courses do not adequately engage in creative or critical thinking in students, even though these qualities are arguably the most important ones for solving difficult and complex problems encountered by scientists and engineers. The difference in performance between students who participate in extracurricular undergraduate research in addition to classwork and their peers relying exclusively on lectures and undergraduate lab courses indicates that there are benefits to learning in a research-focused environment. To prepare the science and engineering majors at Penn State more effectively for their future jobs, we propose to incorporate a research-intensive component into CHEM 457 which is a capstone course for all chemistry and chemical engineering majors. Our aim is to utilize portions of a graduate student teaching assistant’s thesis as the basis of small experiments that are at the appropriate level and time to fit within CHEM 457. We will assess our success by the quality and scientific value of the work that is produced by the undergraduate students using the same metric as the professional scientific community, via publications and professional conferences. The impact of this work fundamentally improves the structure of learning in undergraduate laboratory courses at Penn State, and dramatically enhances the quality of education for undergraduates in science and engineering at Penn State and graduate teaching assistants involved.


[ Project Impact and Need in regard to Undergraduate Education ]

The current instructional model for undergraduates in chemistry and chemical engineering involves spending time learning about concepts and relationships in a lecture setting and then applying those concepts in a laboratory course. This model, while good in theory, suffers from certain logistical problems that inhibit the process of having students make full use of the knowledge that they absorb during lecture courses. A major factor that inhibits true problem solving and knowledge activation in undergraduate laboratory courses is the constraint of standardization for teaching methods and protocols, laboratory techniques, and fundamental concepts from the experiment. High level experiments require time and expertise to set up and perform correctly; a typical 3-4 hr lab period does not leave much room for students to explore and think about the problem beyond the completion of pre-determined procedures and questions. The result is a minimalist mode of instruction that inhibits true thinking and knowledge activation, and instead encourages students to reduce their thinking down to a series of tasks or “checklist style” rationale. The most readily available and effective means of improving the laboratory course experience for undergraduate students within the current 3-4 hr constraints is to require students to work on advanced micro-research projects where they must utilize and organize their knowledge in a way that forces them away from the existing model of predetermined questions, answers, and procedures. This requires highly skilled individuals to teach advanced level coursework.


[ Project Description ]

The immediate plan for this project is to utilize the summer of 2013 to perform preliminary experiments that will be used to design more appropriate and specific experiments for the CHEM 457 and CHEM 459W undergraduate laboratory courses (which is taught by chemistry faculty member Bratoljub H. Milosavljevic, and enrolls approximately 100-120 undergraduates per semester). These experiments are also directly related to the graduate thesis work of Jennifer Tan (tentatively entitled Interactions of Guest Molecules and Quantum Dots with Host Media: Liquids, Molecular Solids & Polymers). The areas of chemistry in this graduate thesis involve theories, principles and experimental work that can be readily incorporated into the curriculum of the CHEM 457 and CHEM 459W physical chemistry lab courses. These topics include photochemistry and photophysics, absorption and emission spectroscopy, IR spectroscopy and vibrational structure, solvent effects and the Frank-Condon principle, kinetics and laser photolysis, thermal characterization of polymers (TGA and DSC), and polymer dynamics. Students learn about these areas in chemistry in their pre- and co-requisite physical chemistry lectures such as chemical thermodynamics (CHEM 450), quantum chemistry (CHEM 452), and molecular thermodynamics (CHEM 466), and can exercise their knowledge in a laboratory setting in CHEM 457 and CHEM 459W.

In the context of improving undergraduate education, the main advantage of the micro-research component in CHEM 457 and CHEM 459W is that the project topics originate from graduate thesis work. This course structure introduces students to working on projects that are part of a more complex and continuous scientific problem. Rather than using an experiment to serve as a simple demonstration of a scientific principle, undergraduates participate in unique and original experiments that are intended to answer a subset of questions that are part of a larger graduate level project. Previous students from CHEM 457 and CHEM 459W have presented their work at ACS conferences[1–4]; the results produced are of high quality and have been incorporated into publications[5–7] and a Ph.D. thesis[8].

The micro-research projects will be briefly described. In the last 4-6 weeks of CHEM 457 the students talk with instructors about the topic of their project, perform a literature search, write a proposal, perform experimental work and data analysis, interpret their data and present their conclusions in a written report, an oral presentation to the class, and a chemistry department undergraduate poster session. The posters are reviewed by peer students and chemistry faculty. Students are under the close guidance of TAs and instructor throughout the project.

In the context of graduate education, the quality of teaching increases for graduate students that are intimately involved in the process designing the experiments for the course. There is a learning curve for new TAs that lasts for approximately 2 semesters before they are proficient enough to guide students through more complex problems or help with designing experiments for students. These skills are essential for working with or supervising other people in a research laboratory, but the teaching responsibilities of most TAs end after 1 or 2 semesters without them advancing beyond superficial knowledge of the course. If graduate students that are directly advised by the course instructor are able teach and do their own research on the equipment on the same equipment, they will have the opportunity to learn how to properly talk to students, organize a laboratory, teach, guide students through complex problems, and gain leadership skills they would otherwise not have been able to obtain in a typical research experience. The time spent teaching is also productive for graduate research because the results are directly applicable to questions in the Ph.D. dissertation.

Maintaining a high level curriculum that relies on generating new individual projects requires a lot of time to be spent reading and thinking of new experiments, as well as collecting preliminary data and judging what kind of experiments are appropriate for the undergraduate level. (Selecting a project that is too difficult or too easy is unproductive.) Experienced TAs are also involved in designing new experiments for CHEM 457[9–12]. During the semester, the time spent maintaining research-grade analytical equipment in a teaching lab, working with undergraduates who are not entirely independent on relatively complex projects, instructing other teaching assistants, and making sure supplies and chemicals are ordered make up a large portion of the available time. In addition, the progress of graduate research is impeded by competition for lab space and instrument time with courses that also use the same lab space (CHEM 423W, CHEM 427W, CHEM 457, CHEM 459W). When classes are in session, certain experiments that use fragile custom equipment cannot be safely performed because there are many untrained individuals circulating the lab space. For the reasons described above, the summer is an ideal time to accomplish a lot of experimental work towards my thesis that are not suitable during the semester.


[ Project Assessment ]

Success in this teaching model is shown by the quality and value of the scientific work produced by both graduate and undergraduate students (as judged by the professional scientific community).

Previous measures of success:

  • Two CHEM 457 experiments from the course manual have been written by TA instructors.[9,12] One CHEM 457 experiment has been written by an undergraduate using his work in CHEM 457 and 459W.[13] These experiments and three more are being prepared into manuscripts to submit to Journal of Chemical Education[9–12,14,15].
  • Previous CHEM 457 and 459W undergraduate projects have been presented at ACS meetings.[1–4]
  • Experimental work by an undergraduate (Andrew Hanlon) in CHEM 457 and CHEM 459W to study pyrene excimer kinetics with an appropriate excitation wavelength has been accepted by Photochemical & Photobiological Sciences.[16]
  • Experimental work by an undergraduate (Angela Hwang) in CHEM 457 has been published[7,17] and incorporated into a graduate thesis[8].
  • Dr. Keith Krise obtained his Ph.D. in the aforementioned circumstances and now has a teaching position at Dickinson College. He produced three publications[5–7]; all articles were related to experiments developed for the physical chemistry laboratory courses, and students working on these projects contributed to the research.
  • The SRTE score of Keith Krise were higher than those of other CHEM 457 TAs. The high TA SRTE score correlated with higher course and instructor SRTE scores. Students are reporting a higher quality of learning in sections taught by a graduate student directly advised by the course instructor. (In spring 2010, Krise received a 6.6, and the instructor received a 5.86 in that section. The same instructor in the same semester teaching the same course received a 2.25 in a different section taught by a different TA.)


  • Compare the SRTE scores of TAs directly involved in this training program to other TAs.
  • Observe the chemistry department undergraduate poster symposium for the quality of projects in the following fall semester. Ideas generated during the summer of 2013 for undergraduate projects will be used in the CHEM 457 and 459W in fall 2013.
  • The work done during the summer of 2013 will contribute to the graduate research of Jennifer Tan, and be included into any publications and the Ph.D. thesis produced.


[ Time Line ]

Experimental techniques I’m developing to study polymer matrix dynamics (and related media):
 - The work done will be used to develop undergraduate micro-research projects for the Fall 2013.

Since recent progress was made on elucidating the mechanism and kinetics on the pyrene excimer formation mechanism and kinetics in our group[17], we intend to use this information to characterize the phase transitions in solid polystyrene (which we intend to use as a medium to study quantum dots in polymers). The polystyrene excimer forms when the distance between individual pendant phenyl groups is short enough that an excited phenyl group electronically couples with a ground state phenyl group, and emits at longer wavelengths that are distinguishable from the emission of the excited phenyl ring. Benzene and toluene can also form excimers (or exciplexes with the phenyl group in polystyrene) and are useful for studying a system where the chromophore is not restricted locally to one site on the polymer backbone, as in polystyrene. Measuring the diffusion coefficient of benzene and toluene in polystyrene and other related media (cyclohexane, polypropylene) will enable us to compare to the matrix dynamics observed in the solid polymer media with the mobility of luminescent molecular probes in other media.

The temperature effect on the photophysics of luminescent molecules in polystyrene and other related media allows for the study of temperature and viscosity dependence on the dynamics in these media, which hasn’t been fully characterized. The monomer/excimer emission ratio as a function of temperature is also useful for understanding matrix dynamics.

Specific experiments I plan to do:

  • Collect emission spectra of polystyrene in cyclohexane (non-emitting solvent) under nitrogen as a function of temperature (observe monomer vs. excimer emission) using a custom glass Dewar with quartz windows. Cyclohexane melt point occurs at 6.5°C, where it becomes solid, opaque, and scatters light.
    • Collect emission spectra of  polystyrene in dichloromethane (m.p. -96.8°C) to compare the solvent effect on the excited electronic state of polystyrene with cyclohexane and to observe the emission spectra without problems from light scattering from phase change from liquid to solid.
    • Run thermogravimetric analysis on sample films of polystyrene cast in benzene, toluene, and cyclohexane to quantify the amount of guest solvent remaining in prepared sample films.
      • Information about amount of solvent present in the film will be used to prepare films of known amounts of guest solvent (using TGA), and the effects of guest solvent on the temperature-resolved emission will be studied.
      • The temperature effect on the polystyrene emission spectrum will be studied in these polystyrene films.
      • Study the kinetics of excimer or exciplex formation in the aforementioned systems in conjunction with temperature-resolved Raman spectroscopy to understand the chemical environment and the vibrational and rotational Raman modes that are active or inactive in the system at different temperatures.
      • Collect temperature-resolved absorption and emission of pyrene in 3-methylpentane (a glass-forming solvent that is a good analog for the solid polymer medium polypropylene) to compare the electronic structure of excited singlet pyrene to previously collected data for pyrene in polypropylene.
      • Begin preparing samples to embed quantum dots (QD520) into polystyrene and polymethyl(methacrylate) to begin collecting data (emission lifetimes from laser photolysis and steady state emission spectra) as a function of temperature.

Experiments to develop for CHEM 457

  • We want to design a lab experiment for CHEM 457 to characterize detergents and quantify their performance as cleaning agents using stalogmometry and photophysics. Properties such as the critical micellar concentration and the aggregation number will be characterized.
    • Chemical engineering majors make up a large portion of the students taking CHEM 457, and are more interested in experiments that have a strong applications component related to physical chemistry.


[ Project Budget ]

  • The amount of support requested totals up to $4000. This money will be used to support one graduate student during the summer of 2013 for research. Some of it will be used to purchase supplies and chemicals.
  • The time during the summer is important for graduate research, because no classes are held and instrumentation is free. Having no teaching responsibilities during the summer allows me to focus and put continuous hours into thinking about my research and run experiments that are more fragile, lengthy, and difficult. Certain experiments are simply impossible to perform during the semester because there is competition for lab space from four undergraduate courses and lab equipment is not available for continuous periods of time.



[1]       Kufta, K. M.; Milosavljevic, B. H. Preferential Solvation of Iodide Anion in Water-Ethanol Mixture – poster presentation (PHYS-415). 244th ACS Conference, Philadelphia 2012.

[2]       Joh, S. Behavior of Cp and luminescence quantum yield of excited guest molecules around Tg of poly(propylene) - poster presentation (PHYS-378). 243rd ACS Conference, San Diego 2012.

[3]       Ellen Forsyth; DiMarco, K. M.; Krise, K. M.; Milosavljevic, B. H. Sonolysis of the Thick Fraction of Egg White – poster presentation (Phys-478). 242nd ACS Conference, Denver 2011.

[4]       Van, T.; Schram, V.; Milosavljevic, B. H. [Ru(bpy)(dmbpy)(phen)]2+ as a Luminescence Probe for Phase Transitions in Glycerol - Water Mixtures – poster presentation (CHED-990). 237th ACS meeting, Salt Lake City 2009.

[5]       Krise, K. M.; Milosavljevic, B. H. Biomacromolecules 2011, 12, 2351–6.

[6]       Krise, K. M.; Milosavljevic, B. H. Journal of Physical Chemistry B 2011, 115, 11964–9.

[7]       Krise, K. M.; Hwang, A. A.; Milosavljevic, B. H. Physical chemistry chemical physics : PCCP 2010, 12, 7695–701.


[9]       Krise, K. M.; Milosavljevic, B. H. The determination of thermodynamic functions of the reactions in commercial alkaline-manganese dioxide galvanic cell (Duracell®). Manuscript in preparation (to be submitted to Journal of Chemical Education).

[10]     Tan, J. G.; Milosavljevic, B. H. Laser Photolysis Study of Pyrene Fluorescence Quenching by Iodide Anion. Manuscript in preparation (to be submitted to Journal of Chemical Education).

[11]     Grieco, C.; Milosavljevic, B. H. Steady State Determination of the Rate Constant and Mechanism of *Ru(II) quenching by O2. Manuscript in preparation (to be submitted to Journal of Chemical Education).

[12]     Kennedy, P. E.; Milosavljevic, B. H. Gravimetric Determination of the Second Virial Coefficient of CO2. Manuscript in preparation (to be submitted to Journal of Chemical Education).

[13]     Hanlon, A. D.; Milosavljevic, B. H. In CHEM 457 Lab course manual; 2012; pp. 8–1 to 8–8.

[14]     Hanlon, A. D.; Milosavljevic, B. H. Pyrene-DMA exciplex is more convenient than pyrene excimer for teaching complex kinetics. Manuscript in preparation (to be submitted to Journal of Chemical Education).

[15]     Krise, K. M.; Forsyth, E. R.; DiMarco, K. M.; Milosavljevic, B. H. Sonolysis of High Macroviscosity Systems: Hen Albumen Hydrogel. J. Phys. Chem. B, Submitted, 12/28/2012, Revision requested, 3/3/13.

[16]     Hanlon, A. D.; Milosavljevic, B. H. Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology 2013.

[17]     Krise, K. M.; Hwang, A. A.; Sovic, D. M.; Milosavljevic, B. H. Journal of Physical Chemistry B 2011, 115, 2759–64.