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Christopher J. Stromberg Time-Resolved Spectroscopy

Current Projects: Time-Resolved Spectroscopy

This project makes use of the time-resolved UV/Visible pump, IR probe laser system (UV-TRIR) at the National Institute of Standards and Technology (NIST) [Link to www.nist.gov] in Gaithersburg, Maryland (shown in Figure 1).

Compounds 1 and 2 (shown in Figure 2) have been studied in heptane using three different pump frequencies (266, 355, and 532 nm). The data are shown in Figure 3.

For 1, two sets of bands are evident. Both sets of bands have the same rise time.

The first set of bands (primarily in blue in Figure 3) represents a long-lived photoproduct. This photoproduct has been assigned as a C≡O loss product. The C≡O loss photoproduct is seen in all three pump wavelengths.

The second set of bands (primarily in green in Figure 3) represents a short-lived photoproduct that has been assigned to a relatively long-lived electronic excited state with an elongated Fe-Fe bond. This excited state decays with a time constant of approximately 150 ps, leaving only the C≡O loss photoproduct. The amount of the short-lived photoproduct varies depending on the pump wavelength used. At 266 nm, almost none of the short-lived photoproduct is observed, but at 532 nm, the short-lived photoproduct is much more prominent. The 355 nm data is intermittent between the two.

Figure 3b shows the data for 2. While the two sets of bands are not as distinct as for 1, the same general picture emerges, with short-lived and long-lived bands, with the proportion between the two depending on the pump wavelength.

We are now continuing our studies with compound 7 (shown in Figure 4). We have taken data on 7 with 532 and 355 nm pump wavelengths. We are currently analyzing this data and hope to publish the results shortly.

This portion of the project was featured in the Journal of Physical Chemistry A:

Bingaman, J. L.; Kohnhorst, C. L.; Van Meter, G. A.; McElroy, B. A.; Rakowski, E. A.; Caplins, B. W.; Gutowski, T. A.; Stromberg, C. J.; Webster, C. E.; Heilweil, E. J., Time-Resolved Vibrational Spectroscopy of [FeFe]-Hydrogenase Model Compounds. The Journal of Physical Chemistry A 2012, 116 (27), 7261-7271. http://dx.doi.org/10.1021/jp2121774

The results of this portion of the project have also been presented at the following conferences:

  1. Benjamin W. Caplins*, Jennifer L. Mehalko*, and Christopher J. Stromberg, "Infrared Spectroscopy of Bio-mimetic Catalysts for Hydrogen Production," 9th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 14, 2006.

  2. Benjamin W. Caplins*, Tiffany A. Gutowski*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Infrared and Raman Spectroscopy of Biomimetic Catalysts for the Production of Hydrogen," American Chemical Society 234th National Meeting, Boston, MA, August 19-23, 2007.

  3. Benjamin W. Caplins*, Tiffany A. Gutowski*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Infrared Spectroscopy of Biomimetic Catalysts for Hydrogen Production," 10th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 13, 2007.

  4. Elizabeth Rakowski*, Casey Kohnhorst*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Linear and Time-Resolved Vibrational Spectroscopy of Bio-Mimetic Catalysts for Hydrogen Production," American Chemical Society 236th National Meeting, Philadelphia, PA, August 17-21, 2008.

  5. Casey Kohnhorst*, Elizabeth Rakowski*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Linear and Time-Resolved Vibrational Spectroscopy of Bio-Mimetic Catalysts for Hydrogen Production," 11th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 11, 2008.

  6. Elizabeth Rakowski*, Casey Kohnhorst*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Linear and Time-Resolved Vibrational Spectroscopy of Bio-Mimetic Catalysts for Hydrogen Production," The Invitrogen Foundation Colloquium, Hood College, Frederick, MD, October 29, 2008.

  7. Casey Kohnhorst*, Glenn Van Meter*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Vibrational Spectroscopy of [FeFe]-hydrogenase Model Compounds," American Chemical Society 238th National Meeting, Washington, DC, August 16-20, 2009.

  8. Casey Kohnhorst*, Glenn Van Meter*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Vibrational Spectroscopy of [FeFe]-hydrogenase Model Compounds," 12th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 10, 2009.

  9. Casey Kohnhorst*, Glenn Van Meter*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Vibrational Spectroscopy of [FeFe]-hydrogenase Model Compounds," Life Technologies Seminar, Hood College, November 18, 2009.

  10. Glenn Van Meter*, Jamie Bingaman*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," Life Technologies Seminar, Hood College, October 25, 2010.

  11. Glenn Van Meter*, Jamie Bingaman*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," 13th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 30, 2010.

  12. Glenn Van Meter*, Jamie Bingaman*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," Undergraduate Research Celebration, Hood College, Frederick, MD, March 5, 2011.

  13. Glenn Van Meter*, Jamie Bingaman*, Edwin J. Heilweil+, and Christopher J. Stromberg, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," American Chemical Society 241st National Meeting, Anaheim, CA, March 27-31, 2011.

  14. Jamie L. Bingaman, Brent A. McElroy, Christopher J. Stromberg, and Edwin J. Heilweil+, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," 14th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 22, 2011.

  15. Jamie L. Bingaman, Brent A. McElroy, Christopher J. Stromberg, and Edwin J. Heilweil+, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," Research Celebration, Hood College, Frederick, MD, March 31, 2012.

  16. Jamie L. Bingaman, Christopher J. Stromberg, and Edwin J. Heilweil+, "Time-Resolved Spectroscopy of [FeFe]-hydrogenase Model Compounds," American Chemical Society 243rd National Meeting, San Diego, CA, March 25-29, 2012.

  17. Melissa A. Johnson, James D. Thuman, Christopher J. Stromberg, and Edwin J. Heilweil+, "Time-Resolved Infrared Spectroscopy of [FeFe]-hydrogenase Model Compounds," 15th Annual Undergraduate Research Symposium in the Chemical and Biological Sciences, UMBC, Baltimore, MD, October 20, 2012.

* – Hood Student
+ – National Institute of Standards and Technology Researcher
__ – Presenter