In-Situ Spectroscopic Detection of Soil and Groundwater Contaminants
The Search for Past Life on Mars: Optical Sensing of Lignins and Kerogens
Spectroscopy and Photophysics of Aromatic Molecules
Innovations in Chemistry Education
Global Warming Potentials of CFC Substitutes
In-Situ Spectroscopic Detection of Soil and Groundwater Contaminants
Much of our research is directed to the development of new analytical instrumentation based on laser-induced fluorescence and other spectroscopies. We have developed several generations of laser-fiber-optic instruments capable of in situ fluorescence measurements, with the primary analytical application being the detection of aromatic organic groundwater contaminants. A novel light source which we developed, consisting of a Nd:YAG-laser-pumped Raman shifter with a gas mixture as the active medium, supplies multiple-wavelength laser beam output simultaneously. An imaging spectrograph and CCD detector complete the parallel-spectroscopy instrumentation which facilitates the measurement of complete three-dimensional fluorescence fingerprints of remote samples. Since all the information is collected simultaneously, samples can be characterized rapidly (in about 1 second), making the technique useful for monitoring flow systems, as in process control, HPLC, and electrophoresis.
We are currently pursuing our original goal of soil and groundwater monitoring using the instrument in a cone penetrometer vehicle, which uses a hydraulic press to insert a small-diameter rod into the ground to depths of 50 m or more. For our measurements, a sapphire window on the side of the rod, near the tip, permits excitation of the sample and collection of fluorescence through fused silica fiber optics. We have recently performed five field tests of the instrument at hazardous waste sites. These have been successful in demonstrating the feasibility of the approach, consistency with laboratory results, and areas of performance most in need
of improvement.
We are developing matrix-based methods for automated analysis of field data. The analysis of in situ fluorescence data from soil is challenging for a number of reasons. The samples are inhomogeneous and highly scattering, and have highly variable particle size (and hence optical path length). The contaminants routinely contain multiple chemical species, and in many instances these are at high enough concentrations to invalidate the optically dilute criterion and to require correction for both inner filter effects and resonant energy transfer among component species. Finally, the specific nature of the soil itself can give rise to changes in the spectrum of a target analyte. We are currently assessing the limitations on the analytical results caused by these effects, as well as developing ways to identify and, if possible, correct the raw data for the effects.
We are considering the addition of other complementary techniques to the CPT probe, including Raman and reflectance spectroscopy. We are pursuing other applications of this technology as well, for example, HPLC, capillary electrophoresis, and non-CPT agricultural applications.
Relevant Publications
Subsurface Contaminant Monitoring by Laser Excitation-Emission Matrix/Cone Penetrometer, J. W. Pepper, Y.-M. Chen, A. O. Wright, and J. E. Kenny, CRC Press, Boca Raton, Florida, 1999, in press.
“In Situ Measurements of Subsurface Contaminants with a Multi-channel Laser-Induced Fluorescence System,” J. W. Pepper, A. O. Wright, and J. E. Kenny, in preparation.
“Two-Fiber Spectroscopic Probe with Improved Scattered Light Rejection,” Andrew O. Wright, Jane W. Pepper, and Jonathan E. Kenny, Analytical Chemistry, in press.
“Subsurface Contaminant Monitoring by Laser Excitation-Emission Matrix/Cone Penetrometer,” J. Pepper, Y.-M. Chen, A. Wright, R. Premasiri, J.E. Kenny. Proc. SPIE 3534, pp. 234-242 (1998).
“A Fiber Optic Laser Induced Fluorescence Excitation Emission Detector Applied to Flow Injection Analysis of PAHs, “ S. J. Hart, G. J. Hall, and J. E. Kenny, Proc., SPIE 3534, pp. 601-611 (1998).
"Laser-Induced Fluorescence and Fast Gas Chromatography/Mass Spectrometry with Subsurface Thermal Extraction of Organics: Field Analytical Technologies for Expediting Site Characterization and Cleanup," A. Robbat Jr., J. E. Kenny, S. Smarason, J. W. Pepper, and A. O. Wright, Remediation Winter 1998, 95-111.
"Field Demonstration of a Multichannel Fiber Optic Laser Induced Fluorescence System in a Cone Penetrometer Vehicle," S. J. Hart, Y.- M. Chen, J. E. Kenny, B. K. Lien and T. W. Best, Field Analytical Chemistry and Technology, 1, 343 (1997).
"A Fiber Optic Multichannel Laser Spectrometer System for Remote Fluorescence Detection in Soils," S.J. Hart, Y.-M. Chen, B.K. Lien, and J.E. Kenny, Proc. SPIE 2835, 73 (1996).
"Improved Two-Fiber Probe for In Situ Spectroscopic Measurements," J. Lin, S. J. Hart, and J.E. Kenny, Analytical Chemistry68, 3098 (1996).
"Subsurface Contaminant Monitoring by Laser Fluorescence Excitation-Emission Spectroscopy in a Cone Penetrometer Probe," J. Lin, S.J. Hart, W. Wang, D. Namychkin and J.E. Kenny, Proc. SPIE2504, 59 (1995).
"Spectroscopy in the Field: Emerging Techniques for On-Site Environmental Measurements," A.Henderson-Kinney and J.E. Kenny, Spectroscopy, 10, No. 7, p. 32 (1995).
"Laser Fluorescence EEM Probe for Cone Penetrometer Pollution Analysis," J. Lin, S. J. Hart, T. A. Taylor and J. E. Kenny,Proc. SPIE 2367, 70 (1994).
"Evaluation of Nd:YAG-Pumped Raman Shifter as a Broad-Spectrum Light Source," G.B. Jarvis, S. Mathew and J.E. Kenny, Appl. Opt. 33, 4938 (1994).
Laser-Based Fluorescence EEM Instrument for In-Situ Groundwater Monitoring", T.A. Taylor, G.B. Jarvis, H. Xu, A.C. Bevilacqua, and J.E. Kenny, Analytical Instrumentation, 21, 141 (1993.)
"Laser Fluorescence EEM Instrument for In Situ Groundwater Screening", T.A. Taylor, H. Xu, and J.E. Kenny, Proc., Second International Symposium on Field Screening Methods for Hazardous Waste Site Investigations, US.EPA, Las Vegas, NV (1991).
"Measurement of Incident Intensity of UV Radiation Delivered by Optical Fibers", H. Xu and J.E. Kenny, Applied Spectroscopy, 45, 429 (1991).
"Groundwater Monitoring Using Remote Laser-Induced Fluorescence", J.E. Kenny, G.B. Jarvis, K.O. Pohlig, and W. A. Chudyk, A.C.S. Symposium Series 383, Luminescence Applications in Biological, Chemical, Environmental, and Hydrological Sciences, M.C. Goldberg, ed., 233 (1989).
"Instrumentation and Methodology for Multicomponent Analysis Using In Situ Laser-Induced Fluorescence", J.E. Kenny, G.B. Jarvis and H. Xu, Proc., First International Symposium on Field Screening Methods for Hazardous Waste Site Investigations, 133 (1988).
"Remote Laser-Induced Fluorescence Monitoring of Groundwater Contaminants: Prototype Field Instrument", J.E. Kenny, G.B. Jarvis, W. A. Chudyk, and K.O. Pohlig, Analytical Instrumentation16, 423 (1987).
"Monitoring of Ground-Water Contaminants Using Laser Fluorescence and Fiber Optics", W.A. Chudyk, J.E. Kenny, G.B. Jarvis, and K. Pohlig, InTech 34, (5), 53 (1987).
"Prototype Laser Fluorescence/Fiber Optics Groundwater Contaminant Detector", W.A. Chudyk, M.M. Carrabba, G.B. Jarvis, and J.E. Kenny, Proc. Specialty Conf. on Environ. Eng., EE Div., 1985, p.98.
"Remote Detection of Groundwater Contaminants Using Far-UV Laser Induced Fluorescence", W.A. Chudyk, M.M. Carrabba, and J.E. Kenny, Anal. Chem., 57, 1237 (1985).
"Remote Analysis of Groundwater Contaminants Using Laser Fluorescence", W.A. Chudyk and J.E. Kenny, Proceedings of Fourth National Symposium and Exposition on Aquifer Restoration and Ground-Water Monitoring, 235 (1984).
The Search for Past Life on Mars: Optical Sensing of Lignins and Kerogens
Despite the negative outcome of the in situ Gas Chromatograph-Mass Spectrometer experiments to detect organic materials carried out by the Viking Mars Lander in the 1970’s, speculation about the possibility of past life on Mars have continued. In addition, evolutionary and exobiologists have made a strong case for the importance of continuing the search in order to answer fundamental questions about the origin of life anywhere in the universe. The recent discovery of “abundant polycyclic aromatic hydrocarbons” in fresh fracture surfaces of the Martian meteorite ALH84001 has stimulated new interest in the search for evidence of past life on Mars, especially as NASA plans for upcoming Mars Explorer missions for 2003-07. NASA scientists and collaborators have directed attention to the ability to detect lignins and kerogens, insoluble macromolecular hydrocarbons with relatively low hydrogen content, containing aromatic and polyaromatic components, which would result from the decay of once-living organisms and might be protected from further chemical and photochemical decomposition at locations below the highly oxidizing surface soil.
We are pursuing the adaptation of our optical spectroscopic probes to the needs of the Mars mission: very tight spatial, weight and power requirements, wide range of operating temperatures, high sensitivity (better than ppb), rugged terrain, etc. We are using our expertise in analysis of multicomponent samples, untangling the signals from physically mixed analytes, to devise an optimum strategy for interpreting the data. For poorly or uncharacterized sample matrices such as those to be encountered on Mars, we will likely deploy some sort of double resonance methodology, involving both vibrational and electronic signatures of the analytes. And since our past work has focused on the smaller molecular species, we are extending that work to characterize lignin and kerogen samples from various terrestrial sources.
Spectroscopy and Photophysics of Aromatic Molecules
We have focused our attention on nonalternant aromatic molecules, particularly azulene (C10H8), which consists of fused five- and seven-membered rings, and its alkyl derivatives. These molecules, the first known violators of Kasha’s rule which states that luminescence originates from the lowest excited state of a given spin multiplicity, have unusual vibrational and electronic structure and dynamics. Using various spectroscopic techniques, including IR, Raman, uv-vis absorption, fluorescence excitation, emission, and double resonance methods, we have characterized the interesting and unusual internal conversion from the two lowest singlet states of azulene, and various other features of some azulene derivatives. Much of this work has been performed in cold, supersonic jets where gas-phase molecules at very low temperatures and isolated or nearly isolated conditions may be probed.
Relevant Publications
"Pushing Pyrazine to the (Statistical) Limit," W.R. Moomaw, T.-Y. Liu and J.E. Kenny, J. Phys. Chem., 99, 7320 (1995).
"Excess Energy Dependence of Internal Conversion in the S1 State of Azulene", S.K. Kulkarni and J.E. Kenny, J. Chem. Phys. 89, 4441 (1988).
"Internal Conversion Rates for Single Vibronic Levels of S2 in Azulene", T.M. Woudenberg, S.K. Kulkarni, and J.E. Kenny, J. Chem. Phys. 89, 2789 (1988).
"Vibrational Spectra and Normal Mode Analysis of Aceheptylene and 3,5,8,10-Tetramethylaceheptylene", A.C. Bevilacqua, C.H. Cho, and J.E. Kenny, Spectrochimica Acta 44A, 23 (1988).
"Excited State Dynamics of Guaiazulene Using Laser-Saturated Fluorescence", M.M. Carrabba, T.M. Woudenberg, and J.E. Kenny, J. Chem. Phys. 86, 552 (1987).
"Conformational Analysis of Guaiazulene in a Supersonic Jet", M.M. Carrabba, T.M. Woudenberg, and J.E. Kenny, J. Phys. Chem., 89, 4226 (1985).
"Hydrogen Bonding in the Lowest Singlet n?* Excited State of Pyrimidine", M.M. Carrabba, J.E. Kenny, W.R. Moomaw, J. Cordes, and M. Denton, J. Phys. Chem., 89, 674 (1985).
"The Lowest Excited Singlet State of Hydrogen Bonded Methyl Salicylate", L.A. Heimbrook, J.E. Kenny, B.E. Kohler, and G.W. Scott, J. Phys. Chem., 87, 280 (1983).
"Vibrational Predissociation and Intramolecular Vibrational Relaxation in Electronically Excited s-tetrazine-Argon van der Waals Complex", D.V. Brumbaugh, J.E. Kenny, and D.H. Levy, J. Chem. Phys., 78, 3415 (1983).
"Dual Fluorescence Excitation Spectra of Methyl Salicylate in a Free Jet", L.A. Heimbrook, J.E. Kenny, B.E. Kohler, and G.W. Scott, J. Chem. Phys., 75, 5201 (1981).
"Free-Jet Fluorescence Excitation Spectrum of trans, trans-1,3,5,7-octatetraene", L.A. Heimbrook, J.E. Kenny, B.E. Kohler, and G.W. Scott, J. Chem. Phys., 75, 4338 (1981).
"Van der Waals Complexes of Iodine with Hydrogen and Deuterium: Intermolecular Potentials and Laser-Induced Photodissociation Studies", J.E. Kenny, T.D. Russell, and D.H. Levy, J. Chem. Phys., 73, 3607 (1980).
"The Photodissociation of van der Waals Molecules: Complexes of Iodine, Neon and Helium", J.E. Kenny, K.E. Johnson, W. Sharfin, and D.H. Levy, J. Chem. Phys., 72, 1109 (1980).
"Nonstatistical Behavior in van der Waals Photochemistry: Tetrazine-Ar", J.E. Kenny, D.V. Brumbaugh, and D.H. Levy, J. Chem. Phys., 71, 4757 (1979).
Innovations in Chemistry Education
We are currently designing an all-new version of the introductory two semester general chemistry course for college science and engineering students. The course is called General Chemistry for Spaceship Earth: the Chemistry of Cosmic Evolution. For the first time, the core topics of general chemistry are being delivered in a narrative format that brings the introductory course material close to the cutting edge of research in chemistry, astrophysics, biology, and other disciplines. Furthermore, pedagogical improvements are being implemented, including the selective use of technology in and beyond the classroom to enhance both the effectiveness of the learning process and the accuracy of evaluating curricular changes. Workshops to disseminate the materials and approaches are planned; they will include current full-time and part-time faculty, and postdoctoral fellows and graduate students planning academic careers. Training sessions for teaching assistants who will be involved in incorporating the new approach at Tufts are also planned. Some funding is currently in place, and further funding from government and corporations and foundations is being sought.
We are also committed to training secondary school chemistry and science teachers to use technology effectively in the classroom. We have assembled a consortium of institutions of higher education, secondary schools, the Massachusetts Department of Education, a software company and a nonprofit organization (Mass Networks) in “Project Pixel,” which is pursuing federal and other support. We have worked with master high school teachers doing fellowships at Tufts University’s Dudley Wright Center for Innovative Science Teaching in the past, and formed a collaboration with the Director of the Center, Eric Chaisson, to enhance the effectiveness of current programs and the dissemination of their results.
Global Warming Potentials of CFC Substitutes
In collaboration with Professor Illinger, we have recently completed a study of global warming potentials of CFC replacements and their decomposition productsusing ab initio calculations.
Relevant Publications
“Reassignment of the vibrational spectra of CHF2CH3 (HFC-152a), CF3CH3 (HFC-143a), CF3CHF2 (HFC-125), and CHCl2CF3 (HCFC-123),” S. Tai, S. Papasavva, J. E. Kenny, B. D. Gilbert, J. A. Janni, J. I. Steinfeld, J.D. Taylor and R.D. Weinstein, Spectrochimica Acta55A, pp. 9-24 (1999).
"Infrared Radiative Forcing of CFC-Replacements and their Atmospheric Reaction Products," S. Papasavva, S. Tai, K.H. Illinger, and J.E. Kenny, J. Geophys. Research, 102, 13643 (1997).
"Molecular Properties of CFC Substitutes from Ab Initio Calculations: CFCl2CH3, CF2ClCH3, CHCl2CF3, and CHFClCF3," S. Papasavva, K.H. Illinger, and J.E. Kenny, J. Mol. Structure: THEOCHEM, 393, 73 (1997).
"Ab Initio Calculations on Fluoroethanes: Geometries, Dipole Moments, Vibrational Frequencies and Infrared Intensities," S. Papasavva, K.H. Illinger and J.E. Kenny, J. Phys. Chem., 100, 10100 (1996).
"Ab Initio Calculations of Vibrational Frequencies and Infrared Intensities for Global Warming Potential of CFC Substitutes: CH2FCF3 (HFC-134a)," S. Papasavva, S. Tai, A. Esslinger, K.H. Illinger, and J.E. Kenny, J. Phys. Chem., 99, 3438 (1995).