Joseph S. Francisco

University of Nebraska at Lincoln, Lincoln, Nebraska, United States

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Publications (499)1807.3 Total impact

  • Ryan C. Fortenberry · Joseph S. Francisco ·

    The Journal of Chemical Physics 11/2015; 143(18):184301. DOI:10.1063/1.4935056 · 2.95 Impact Factor
  • Manoj Kumar · Joseph S Francisco ·
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    ABSTRACT: The gas-phase decomposition of the α-hydroxy methylperoxy radical has been theoretically examined, and the results provide insight into a new source of the hydroperoxy radical (HO2 ) in the troposphere. Bimolecular peroxy decomposition is promoted by the red-light or near-IR radiation excitation. The calculations suggest for the first time, an important chemical role for the H2 O⋅HO2 radical complex that exist in significant abundance in the troposphere. In particular, the reaction of organic peroxy radicals with the HO2 radical and the H2 O⋅HO2 radical complex represent an autocatalytic source of atmospheric HO2 . This reaction is a new example of red-light-initiated atmospheric chemistry that may help in understanding the discrepancy between the observed and measured levels of the HOx at sunrise.
    Angewandte Chemie International Edition 11/2015; DOI:10.1002/anie.201509311 · 11.26 Impact Factor
  • Chasity B Love-Nkansah · Lei Tan · Joseph S Francisco · Yu Xia ·
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    ABSTRACT: Homocysteine sulfinyl radical ((SO⋅) Hcy) is a reactive intermediate involved during oxidative damage of DNA in the presence of high concentrations of homocysteine (Hcy). The short lifetime of (SO⋅) Hcy makes its preparation, isolation, and characterization challenging using traditional chemical measurement tools. Herein, we demonstrate the first study on mass-selected protonated (SO⋅) Hcy ions in the gas phase by investigating its unimolecular dissociation pathways from low energy collision-induced dissociation (CID). Tandem mass spectrometry (MS/MS), stable-isotope labeling, and theoretical calculations were employed to rationalize the observed fragmentation pathways. The dominant dissociation channel of protonated (SO⋅) Hcy was a charge-directed H2 O loss from the protonated sulfinyl radical (-SO⋅) moiety, forming a thiyl radical (-S⋅), which further triggered sequential radical-directed ⋅SH loss through multiple pathways. Compared to cysteine sulfinyl radical ((SO⋅) Cys), the small structural change induced by one additional methylene group in the side chain of (SO⋅) Hcy significantly promotes its base property while reducing the radical reactivity of sulfinyl radical. This observation provides new insight into studying reactions of (SO⋅) Hcy with biomolecules, which are critical in understanding toxicity induced by high levels of Hcy in biological conditions.
    Chemistry - A European Journal 11/2015; DOI:10.1002/chem.201502642 · 5.73 Impact Factor
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    ABSTRACT: A semi-global potential energy surface (PES) and quartic force field (QFF) based on fitting high-level electronic structure energies are presented to describe the structures and spectroscopic properties of NNHNN+. The equilibrium structure of NNHNN+ is linear with the proton equidistant between the two nitrogen groups and thus of D∞h symmetry. Vibrational second-order perturbation theory (VPT2) calculations based on the QFF fails to describe the proton "rattle" motion, i.e., the antisymmetric proton stretch, due to the very flat nature of PES around the global minimum, but per- forms properly for other modes with sharper potential wells. Vibrational self-consistent field/virtual state configuration interaction (VSCF/VCI) calculations using a version of MULTIMODE without angular momentum terms successfully describe this motion and predict the fundamental to be at 759 cm-1. This is in good agreement with the value of 746 cm-1 from a fixed-node diffusion Monte Carlo calculation and the experi- mental Ar-tagged result of 743 cm-1. Other VSCF/VCI energies are in good agreement with other experimentally reported ones. Both double-harmonic intensity and rigorous MULTIMODE intensity calculations show the proton-transfer fundamental has strong intensity.
    The Journal of Physical Chemistry A 11/2015; DOI:10.1021/acs.jpca.5b09682 · 2.69 Impact Factor
  • Xian-Hu Zha · Qing Huang · Jian He · Heming He · Junyi Zhai · Yue Wu · Joseph S. Francisco · Shiyu Du ·
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    ABSTRACT: In this work, we investigate the thermal and electrical properties of oxygen-functionalized M2CO2 (M = Ti, Zr, Hf) MXenes using first-principles calculations. Hf2CO2 is found to exhibit a thermal conductivity better than MoS2 and phosphorene. The room temperature thermal conductivity along the armchair direction is determined to be 86.25-131.2 Wm-1K-1 with a flake length of 5-100 um, and the corresponding value in the zigzag direction is approximately 42% of that in the armchair direction. Other important thermal properties of M2CO2 are also considered, including their specific heat and thermal expansion coefficients. The theoretical room temperature thermal expansion coefficient of Hf2CO2 is 6.094x10-6 K-1, which is lower than that of most metals. Moreover, Hf2CO2 is determined to be a semiconductor with a band gap of 1.657 eV and to have high and anisotropic carrier mobility. At room temperature, the Hf2CO2 hole mobility in the armchair direction (in the zigzag direction) is determined to be as high as 13.5x103 cm2V-1s-1 (17.6x103 cm2V-1s-1), which is comparable to that of phosphorene. Broader utilization of Hf2CO2 as a material for nanoelectronics is likely because of its moderate band gap, satisfactory thermal conductivity, low thermal expansion coefficient, and excellent carrier mobility. The corresponding thermal and electrical properties of Ti2CO2 and Zr2CO2 are also provided here for comparison. Notably, Ti2CO2 presents relatively low thermal conductivity and much higher carrier mobility than Hf2CO2, which is an indication that Ti2CO2 may be used as an efficient thermoelectric material.
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    Tarek Trabelsi · O. Yazidi · J. S. Francisco · R. Linguerri · M. Hochlaf ·
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    ABSTRACT: The low-energy electronic states of NSO anion and its SNO isomeric form for the singlet, triplet, and quintet spin multiplicities have been investigated by accurate ab initio approaches and large atomic basis sets. One-dimensional cuts of the three-dimensional potential energy surfaces (PESs) along selected interatomic distances and bending angles for these states have been calculated to assess the formation and stability of NSO− and SNO− in the gas phase. Results show that these anions have two low-energy states ( X˜1A′ and 13A″) that are bound and stable with respect to electron detachment. Owing to the energetic position of the dissociating asymptotes of the neutral and anionic species, several electronic excited states are suggested to be stable with respect to the electron autodetachment process in the long-range parts of the potentials before reaching the molecular region. The nature of the PESs in these regions and their implications and effects on the formation of SNO− from atomic and molecular fragments are discussed. This information is essential for a better understanding of the potential role of these species in diverse media.
    The Journal of Chemical Physics 10/2015; 143(16). DOI:10.1063/1.4933115 · 2.95 Impact Factor
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    ABSTRACT: Results are presented that suggest that thiazyl hydride (HSN)/thionitrosyl hydride (sulfimide, HNS) can be used as light-sensitive compounds for NO-delivery in biological media, as well as markers for the possible detection of intermediates in nitrites + H2S reactions at the cellular level. They are expected to be more efficient than the HNO/HON isovalent species and hence they should be considered instead. A set of characteristic spectroscopic features are identified that could aid in the possible detection of these species in the gas phase or in biological environments. The possibility of intramolecular dynamical processes involving excited states that are capable of interconverting HNS and its isomeric form HSN is examined.
    The Journal of Chemical Physics 10/2015; 143(13):134301. DOI:10.1063/1.4932084 · 2.95 Impact Factor
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    ABSTRACT: We use ab initio calculations to investigate the energetics and kinetics associated with carbinolamine formation resulting from the addition of dimethylamine to formaldehyde catalyzed by a single water molecule. Further, we compare the energetics for this reaction with that for the analogous reactions involving respectively, methylamine and ammonia. We find that the reaction barrier for the addition of these nitrogen containing molecules onto formaldehyde decreases along the series: ammonia, methylamine, and dimethylamine. Hence, starting with ammonia, the reaction barrier can be "tuned" by the substitution of an alkyl group in place of a hydrogen atom. The reaction involving dimethylamine has the lowest barrier with the transition state (TS) being 5.4 kcal/mol below the (CH3)2NH + H2CO + H2O separated reactants. This activation energy is significantly lower than that for the bare reaction occurring without water, H2CO + (CH3)2NH, which has a barrier of 20.1 kcal/mol. The negative barrier associated with the single-water molecule catalyzed reaction of dimethylamine with H2CO to form the carbinolamine (CH3)2NCH2OH suggests that this reaction should be energetically feasible under atmospheric conditions. This is confirmed by rate calculations which suggest that the reaction will be facile even in the gas phase. As amines and oxidized organics containing carbonyl functional groups are common components of secondary organic aerosols (SOA), the present finding has important implications for understanding how larger, less volatile organic compounds, can be generated in the atmosphere by combining readily available smaller components as required for promoting aerosol growth.
    The Journal of Physical Chemistry A 09/2015; DOI:10.1021/acs.jpca.5b04887 · 2.69 Impact Factor
  • Bifeng Zhu · Xiaoqing Zeng · Helmut Beckers · Joseph S. Francisco · Helge Willner ·
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    ABSTRACT: Atmospheric Chemistry. In their Communication on page 11404 ff., H. Beckers et al. report the isolation of methylsulfonyloxyl radicals, key intermediates in the atmospheric oxidation of dimethyl sulfide.
    Angewandte Chemie International Edition 09/2015; 54(39):n/a-n/a. DOI:10.1002/anie.201583961 · 11.26 Impact Factor
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    ABSTRACT: In the present work, the behavior of He in the MAX phase Ti3AlC2 material is investigated using first-principle methods. It is found that, according to the predicted formation energies, a single He atom favors residing near the Al plane in Ti3AlC2. The results also show that Al vacancies are better able to trap He atoms than either Ti or C vacancies. The formation energies for the secondary vacancy defects near an Al vacancy or a C vacancy are strongly influenced by He impurity content. According to the present results, the existence of trapped He atoms in primary Al vacancy can promote secondary vacancy formation and the He bubble trapped by Al vacancies has a higher tendency to grow in the Al plane of Ti3AlC2. The diffusion of He in Ti3AlC2 is also investigated. The energy barriers are approximately 2.980 eV and 0.294 eV along the c-axis and in the ab plane, respectively, which means that He atoms exhibit faster migration parallel to the Al plane. Hence, the formation of platelet-like bubbles nucleated from the Al vacancies is favored both energetically and kinetically. Our calculations also show that the conventional spherical bubbles may be originated from He atoms trapped by C vacancies. Taken together, these results are able to explain the observed formation of bubbles in various shapes in recent experiments. This study is expected to provide new insight into the behaviors of MAX phases under irradiation from electronic structure level in order to improve the design of MAX phase based materials.
    The Journal of Chemical Physics 09/2015; 143(11). DOI:10.1063/1.4931398 · 2.95 Impact Factor
  • Joseph S. Francisco ·
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    ABSTRACT: Cross-cultural collaboration, when it works, is synergistic, and brings understanding between partners that neither is likely to be able to develop alone. There are people in the world that know something, but nobody knows everything. International collaborations in science bring together and capitalize on the dispersal of knowledge and resources across the globe, and the human desire to advance knowledge …” Read more in the Editorial by Joseph S. Francisco.
    Angewandte Chemie International Edition 09/2015; DOI:10.1002/anie.201505267 · 11.26 Impact Factor
  • Joseph S. Francisco ·
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    ABSTRACT: Interkulturelle Kooperation ist, wenn sie funktioniert, synergistisch und bringt ein Verstehen von Partnern mit sich, das jeder für sich allein wohl kaum erreichen kann. Überall auf der Welt gibt es Menschen, die etwas wissen, doch niemand weiß alles. Internationale Kooperationen bringen Wissen und Ressourcen zusammen und ziehen Nutzen aus deren weltweiter Verbreitung und dem menschlichen Streben nach mehr Wissen …” Lesen Sie mehr im Editorial von Joseph S. Francisco.
    Angewandte Chemie 09/2015; DOI:10.1002/ange.201505267
  • Hui Li · Joseph S Francisco · Xiao Cheng Zeng ·
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    ABSTRACT: Recently reported synthetic organic nanopore (SONP) can mimic a key feature of natural ion channels, i.e., selective ion transport. However, the physical mechanism underlying the K(+)/Na(+) selectivity for the SONPs is dramatically different from that of natural ion channels. To achieve a better understanding of the selective ion transport in hydrophobic subnanometer channels in general and SONPs in particular, we perform a series of ab initio molecular dynamics simulations to investigate the diffusivity of aqua Na(+) and K(+) ions in two prototype hydrophobic nanochannels: (i) an SONP with radius of 3.2 Å, and (ii) single-walled carbon nanotubes (CNTs) with radii of 3-5 Å (these radii are comparable to those of the biological potassium K(+) channels). We find that the hydration shell of aqua Na(+) ion is smaller than that of aqua K(+) ion but notably more structured and less yielding. The aqua ions do not lower the diffusivity of water molecules in CNTs, but in SONP the diffusivity of aqua ions (Na(+) in particular) is strongly suppressed due to the rugged inner surface. Moreover, the aqua Na(+) ion requires higher formation energy than aqua K(+) ion in the hydrophobic nanochannels. As such, we find that the ion (K(+) vs. Na(+)) selectivity of the (8, 8) CNT is ∼20× higher than that of SONP. Hence, the (8, 8) CNT is likely the most efficient artificial K(+) channel due in part to its special interior environment in which Na(+) can be fully solvated, whereas K(+) cannot. This work provides deeper insights into the physical chemistry behind selective ion transport in nanochannels.
    Proceedings of the National Academy of Sciences 09/2015; 112(35):10851-6. DOI:10.1073/pnas.1513718112 · 9.67 Impact Factor
  • Jie Zhong · Yu Zhao · Lei Li · Hui Li · Joseph S Francisco · Xiao Cheng Zeng ·
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    ABSTRACT: We present a comprehensive computational study of NH2 (radical) solvation in a water nanodroplet. The ab initio Born-Oppenheimer molecular dynamics simulation shows that NH2 tends to accumulate at the air-water interface. The hydrogen bonding analysis shows that compared to the hydrogen bond of HNH··OH2, the hydrogen bond of HOH··NH2 is the dominant interaction between NH2 and water. Due to the loose hydrogen bonding network formed between NH2 and the droplet interface, the NH2 can easily move around on the droplet surface, which speeds up the dynamics of NH2 at the air-water interface. Moreover, the structural analysis indicates that the NH2 prefers an orientation such that both N atom and one of its H atoms interact with the water droplet while the other H atom is mostly ex-posed to the air. The exposed hydrogen becomes a more probable reactive site for reaction at the water interface. More importantly, the solvation of NH2 modifies the amplitude of vibration of the N-H bond, thereby affecting the Mulliken charges and electrophilicity of NH2. As such, reactive properties of the NH2 are altered by the droplet interface and this can either speed up reactions or allow other reactions processes to occur in the atmosphere. Hence, the solvation of NH2 on water droplets, in chemistry of the atmosphere, may not be negligible when considering the effects of clouds.
    Journal of the American Chemical Society 09/2015; 137(37). DOI:10.1021/jacs.5b07354 · 12.11 Impact Factor
  • Ryan C. Fortenberry · Joseph S. Francisco ·
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    ABSTRACT: The SNO and OSN radical isomers are likely to be of significance in atmospheric and astrochemistry, but very little is known about their gas phase spectroscopic properties. State-of-the-art ab initio composite quartic force fields are employed to analyze the rovibrational features for both systems. Comparison to condensed-phase experimental data for SNO has shown that the 1566.4 cm−1 ν1 N–O stretch is indeed exceptionally bright and likely located in this vicinity for subsequent gas phase experimental analysis. The OSN ν1 at 1209.4 cm−1 is better described as the antisymmetric stretch in this molecule and is also quite bright. The full vibrational, rotational, and rovibrational data are provided for SNO and OSN and their single 15N, 18O, and 34S isotopic substitutions in order to give a more complete picture as to the chemical physics of these molecules.
    The Journal of Chemical Physics 08/2015; 143(8). DOI:10.1063/1.4929472 · 2.95 Impact Factor
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    ABSTRACT: Even though quartic force fields (QFFs) and highly accurate coupled cluster computations describe the OCHCO(+) cation at equilibrium as a complex between carbon monoxide and the formyl cation, two notable and typical interstellar and atmospheric molecules, the prediction from the present study is that the equilibrium C∞v structure is less relevant to observables than the saddle-point D∞h structure. This is the conclusion from diffusion Monte Carlo and vibrational self-consistent field/virtual state configuration interaction calculations utilizing a semi-global potential energy surface. These calculations demonstrate that the proton "rattle" motion (ν6) has centrosymmetric delocalization of the proton over the D∞h barrier lying only 393.6 cm(-1) above the double-well OCHCO(+) C∞v minima. As a result, this molecule will likely appear D∞h, and the rotational spectrum will be significantly dimmer than the computed equilibrium 2.975 D center-of-mass dipole moment indicates. However, the proton transfer fundamental, determined to be at roughly 300 cm(-1), has a very strong intensity. This prediction as well as those of other fundamentals should provide useful guides for laboratory detection of this cation. Finally, it is shown that the two highest energy QFF-determined modes are actually in good agreement with their vibrational configuration interaction counterparts. These high-level quantum chemical methods provide novel insights into this fascinating and potentially common interstellar molecule.
    The Journal of Chemical Physics 08/2015; 143(071102). DOI:10.1063/1.4929345 · 2.95 Impact Factor
  • Hongmin Li · Zhuang Wu · Dingqing Li · Xiaoqing Zeng · Helmut Beckers · Joseph S Francisco ·
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    ABSTRACT: Thiophosphoryl nitrene, R2P(S)N, is a thiazirine-like intermediate that has been chemically inferred from trapping products in early solution studies. Herein, photolysis of the simplest thiophosphoryl azide, F2P(S)N3, in solid noble gas matrices enables a first-time spectroscopic (IR and UV-Vis) identification of thiophosphoryl nitrene, F2P(S)N, in its singlet ground state. Upon visible light irradiation (≥ 495 nm), it converts into the thionitroso isomer F2P-N=S, which can also be produced in the gas phase from flash vacuum pyrolysis of F2P(S)N3. Further irradiation of F2P-NS with UV light of 365 nm leads to the reformation of F2P(S)N and isomerizn ation to a thiazyl species F2P-S≡N.
    Journal of the American Chemical Society 08/2015; 137(34). DOI:10.1021/jacs.5b07302 · 12.11 Impact Factor
  • Bifeng Zhu · Xiaoqing Zeng · Helmut Beckers · Joseph S Francisco · Helge Willner ·
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    ABSTRACT: The methylsulfonyloxyl radical, CH3 SO3 , one of the key intermediates in the atmospheric oxidation of dimethyl sulfide (DMS), was generated by flash pyrolysis of CH3 SO2 OOSO2 CH3 and subsequently isolated in solid noble-gas matrices. The radical has been characterized by UV/Vis and IR spectroscopy and its tautomerization to CH2 SO3 H observed upon irradiation with light of λ≥360 nm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 08/2015; 54(39). DOI:10.1002/anie.201503776 · 11.26 Impact Factor
  • Bifeng Zhu · Xiaoqing Zeng · Helmut Beckers · Joseph S. Francisco · Helge Willner ·
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    ABSTRACT: Das Methylsulfonyloxyl-Radikal, CH3SO3, ein Schlüsselintermediat der atmosphärischen Oxidation von Dimethylsulfid (DMS), wurde durch Blitzpyrolyse von CH3SO2OOSO2CH3 erzeugt und nachfolgend in festen Edelgas-Matrizen isoliert. Das Radikal wurde charakterisiert über seine UV/Vis- und IR-Spektren, sowie seine Tautomerisierung zum CH2SO3H unter Bestrahlung mit Licht von λ≥360 nm.
    Angewandte Chemie 08/2015; 127(39). DOI:10.1002/ange.201503776
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    ABSTRACT: We investigate the lowest electronic states of doublet and quartet spin multiplicity states of HNS− and HSN− together with their parent neutral triatomic molecules. Computations were performed using highly accurate ab initio methods with a large basis set. One-dimensional cuts of the full-dimensional potential energy surfaces (PESs) along the interatomic distances and bending angle are presented for each isomer. Results show that the ground anionic states are stable with respect to the electron detachment process and that the long range parts of the PESs correlating to the SH− + N, SN− + H, SN + H−, NH + S−, and NH− + S are bound. In addition, we predict the existence of long-lived weakly bound anionic complexes that can be formed after cold collisions between SN− and H or SH− and N. The implications for the reactivity of these species are discussed; specifically, it is shown that the reactions involving SH−, SN−, and NH− lead either to the formation of HNS− or HSN− in their electronic ground states or to autodetachment processes. Thus, providing an explanation for why the anions, SH−, SN−, and NH−, have limiting detectability in astrophysical media despite the observation of their corresponding neutral species. In a biological context, we suggest that HSN− and HNS− should be incorporated into H2S-assisted heme-catalyzed reduction mechanism of nitrites in vivo.
    The Journal of Chemical Physics 07/2015; 143(143):34303-134309. DOI:10.1063/1.4926941 · 2.95 Impact Factor

Publication Stats

7k Citations
1,807.30 Total Impact Points


  • 2014-2015
    • University of Nebraska at Lincoln
      • • College of Arts and Sciences
      • • Department of Chemistry
      Lincoln, Nebraska, United States
  • 1994-2015
    • Purdue University
      • • Department of Chemistry
      • • Department of Earth and Atmospheric Sciences
      West Lafayette, Indiana, United States
    • NASA
      Вашингтон, West Virginia, United States
  • 2001-2010
    • Haverford College
      • Department of Chemistry
      Norristown, Pennsylvania, United States
  • 1987-2007
    • Wayne State University
      • Department of Chemistry
      Detroit, MI, United States
  • 2005
    • Bergische Universität Wuppertal
      • Inorganic Chemistry
      Wuppertal, North Rhine-Westphalia, Germany
  • 2002
    • Texas A&M University
      • Department of Chemistry
      College Station, Texas, United States
  • 1999
    • Williams College
      • Department of Chemistry
      Williamstown, New Jersey, United States
    • California State University, Los Angeles
      • Department of Chemistry and Biochemistry
      Los Ángeles, California, United States
  • 1998
    • University of Illinois, Urbana-Champaign
      • Department of Atmospheric Sciences
      Urbana, Illinois, United States
  • 1993-1997
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
  • 1990-1995
    • University of Bath
      • Department of Chemistry
      Bath, ENG, United Kingdom
  • 1991
    • Griffith University
      Southport, Queensland, Australia
  • 1988
    • University of Detroit Mercy
      • Department Chemistry and Biochemistry
      Detroit, Michigan, United States
  • 1984-1985
    • University of Cambridge
      Cambridge, England, United Kingdom
  • 1981-1984
    • Massachusetts Institute of Technology
      • Department of Chemistry
      Cambridge, Massachusetts, United States
    • University of Adelaide
      • School of Chemical Engineering
      Tarndarnya, South Australia, Australia