研究领域
Physical Chemistry Theoretical Chemistry Chemical Dynamics Surface Science — Femtosecond lasers in the visible and infrared are used to study energy transfer, relaxation, and primary processes in chemical reactions in liquids and the dynamical properties of electrons at interfaces and surfaces on ultrafast timescales.
Physical Chemistry Theoretical Chemistry Chemical Dynamics Surface Science — Femtosecond lasers in the visible and infrared are used to study energy transfer, relaxation, and primary processes in chemical reactions in liquids and the dynamical properties of electrons at interfaces and surfaces on ultrafast timescales.
Research projects going on in the group are two-fold. They include the study of the statistical or dynamical basis of chemical reactions in condensed phase on the femtosecond time scale and the dynamics and properties of electrons on surfaces and at interfaces. Femtosecond lasers and ultrahigh vacuum technology provide a unique opportunity to study the dynamics of electrons at metal-dielectric and metal-semiconductor interfaces. The femtosecond two-photon photoemission (TPPE) technique utilizes a femtosecond pump pulse to excite electrons from the metal substrate into states associated with the surface. Photoemission of the surface electrons with a second femtosecond pulse allows one to follow the various surface properties in real time since the photoemission intensity as a function of time delay between the pump and the probe pulse directly reveals the dynamics of the surface electron population. Layer-by-layer growth of dielectrics and large band gap semiconductors on metal surfaces influences the binding energies, lifetimes, and spatial distributions of electrons on surfaces and at interfaces. Studies of Xe overlayers have shown the evolution of metal surface states into quantum well states. Overlayers of n-alkanes result in self-trapping of initially delocalized electrons into localized small polarons. We have studied two dimensional solvation of electrons interacting with nitrile and alcohol overlayers on silver surfaces. Current studies focus on extending our understanding of electronic structure and dynamics to technologically important systems. In general these methods enable us to study the dynamics of electrons interacting with condensed matter in 2-D and how the properties change as the system evolves into 3-D.
The second area, femtosecond infrared and ultraviolet and visible spectroscopic methods are utilized to investigate the dynamics of complex chemical reactions in solution. The most basic reactions in solution share certain reaction processes, which include dissociation, recombination, solvent caging, molecular morphology changes, and system-solvent interaction. These molecular events, which underlie our basic understanding of reaction dynamics, occur on ultrafast (10-13-10-10 s) timescales. Our research utilizes femtosecond experimental techniques along with modern computational methods to study these fundamental issues. The femtosecond infrared lasers developed in our group enable us to study a variety of chemical systems in both the time and spectral domain and as such we can follow elementary chemical reaction events as they occur. There are also workstations capable of carrying out large-scale, high-level quantum chemical calculations and molecular dynamics (MD) simulations. Theoretical methods including ab initio and density functional theory (DFT) as well as MD are utilized to assist interpretation and realization of experimental results. The combined experimental and theoretical approach leads to a deeper understanding of these fundamental processes. Not only do the results of these studies address the issues outlined above, but they are also of interest to researchers throughout the many subdisciplines in chemistry including biological, organometallic, inorganic, and organic chemistry.
In many instances the theoretical basis for the experiments and observations must also be developed. As a result graduate students from Professor Harris's group often obtain their Ph.D. with a strong background in both theory and experiment.
近期论文
查看导师新发文章
(温馨提示:请注意重名现象,建议点开原文通过作者单位确认)
"Primary photochemical dynamics of metal carbonyl dimers and clusters in solution: Insights into the results of metal-metal bond cleavage from ultrafast spectroscopic studies," J. P. Lomont, and C. B. Harris, Inorg. Chim. Acta, 424, 38-50 (2015).
"Vibrational Cooling Dynamics of a [FeFe]-Hydrogenase Mimic Probed by Time-Resolved Infrared Spectroscopy," B. W. Caplins, J. P. Lomont, S. C Nguyen, and C. B. Harris, J. Phys. Chem. A., 118(49), 11529-11540 (2014).
"Exploring the Potential of Fulvalene Dimetals as Platforms for Molecular Solar Thermal Energy Storage: Computations, Syntheses, Structures, Kinetics, and Catalysis," K. B�rjesson, D. Coso, V. Gray, J. C. Grossman3, J. Guan, C. B. Harris, N. Hertkorn, Z. Hou, Y. Kanai, D. Lee, J. P. Lomont, A. Majumdar, S. K. Meier, K. Moth-Poulsen, R. L. Myrabo, S. C. Nguyen, R. A. Segalman, V. Srinivasan, W. B. Tolman, N. Vinokurov, P. C. Vollhardt, and T. W. Weidman, Chem. Eur. J., 20(47), 15587-15604 (2014).
"Exploring the Utility of Tandem Thermal-Photochemical CO Delivery with CORM-2," J. P. Lomont, S. C. Nguyen, and C. B. Harris, Organometallics, 33(21), 6179-6185 (2014).
"Direct Observation of Metal Ketenes Formed by Photoexcitation of a Fischer Carbene using Ultrafast Infrared Spectroscopy," S. C. Nguyen, J. P. Lomont, M. C. Zoerb, P. V. Pham, J. F. Cahoon, and C. B. Harris, Organometallics, 33(21), 6149-6153 (2014).
"Studying the Dynamics of Photochemical Reactions via Ultrafast Time-Resolved Infrared Spectroscopy of the Local Solvent," S. C. Nguyen , J. P. Lomont , B. W. Caplins, and C. B. Harris, J. Phys. Chem. Lett., 5(17), 2974-2978 (2014).
"Ultrafast Infrared Studies of the Role of Spin States in Organometallic Reaction Dynamics," Justin P Lomont , Son C. Nguyen , and Charles B. Harris, Acc. Chem. Res., 47, 1634-1642 (2014).
"New Insights into the Photochemistry of [CpFe(CO)2]2 Using Picosecond through Microsecond Time-Resolved Infrared Spectroscopy (TRIR)," Christopher M. Brookes, Justin P. Lomont, Son C. Nguyen, James A. Calladine, Xue-Zhong Sun, Charles B. Harris, Michael W. George, Polyhedron, 72, 130-134 (2014).
"Reactivity of TEMPO Toward 16- and 17-Electron Organometallic Reaction Intermediates: A Time-Resolved IR Study," Justin P Lomont , Son Chi Nguyen , and Charles B. Harris, J. Am. Chem. Soc., 135 (30), 11266-11273 (2013).
"Determining Equilibrium Fluctuations Using Temperature-Dependent 2D-IR," Adam D Hill , Matthew C. Zoerb , Son Chi Nguyen , Justin P Lomont , Miriam A Bowring , and Charles B. Harris, J. Phys. Chem. B., 117 (49), 15346-15355 (2013).
"Insights into the photochemical disproportionation of transition metal dimers on the picosecond timescale," J. P. Lomont, S. C. Nguyen, C. B. Harris, . Phys. Chem. A. 117, 3777-3785 (2013).
"Switching from Ru to Fe: Picosecond IR Spectroscopic Interrogation of the Potential of the (Fulvalene)tetracarbonyldiiron Framework for Molecular Solar-Thermal Storage," Z. Hou, S. C. Nguyen, J. P. Lomont, C. B. Harris, N. Vinokurov, K. P. C. Vollhardt, Phys. Chem. Chem. Phys. 15, 7466-7469 (2013).
"Picosecond TRIR Studies of M3(CO)12 Clusters in Solution," J. P. Lomont, A. J. Shearer, S. C. Nguyen, C. B. Harris, Organometallics, 32, 2178-2186 (2013).
"A Simulation Program for Dynamic Infrared (IR) Spectra," M. C. Zoerb, C. B. Harris, J. Chem. Ed., 90, 506-507 (2013).
"Direct Observation of a Bent Carbonyl Ligand in a 19-Electron Transition Metal Complex," J. P. Lomont, S. C. Nguyen, C. B. Harris, J. Phys. Chem. A, 117, 2317-2324 (2013).
"Mass Effect on Rotational Diffusion of Small Solutes in Solution"S. C. Nguyen, J. P. Lomont, C. B. Harris, Chem. Phys., Available Online (2013).
"X-ray Transient Absorption and Picosecond IR Spectroscopy of Fulvalene(tetracarbonyl)diruthenium on Photoexcitation." M.R. Harpham, S.C. Nguyen, Z. Hou, J.C. Grossman, C.B. Harris, M.W. Mara, A.B. Stickrath, Y. Kanai, A.M. Kolpak, D. Lee, D.-J. Liu, J.P. Lomont, K. Moth-Poulson, N. Vinokurov, L.X. Chen, and K.P.C. Vollhardt, Angew. Chem. Int. Ed. , 51, 7692 -7696 (2012).
"Ultrafast TRIR and DFT Studies of the Photochemical Dynamics of Co4(CO)12 in Solution" J.P. Lomont, S.C. Nguyen, and C.B. Harris, Organometallics, 31, 4031-4038 (2012).
"Chemistry of the Triplet 14-electron Complex Fe(CO)3 in Solution Studied by Ultrafast Time-resolved IR Spectroscopy" S.C. Nguyen, J.P. Lomont, M.C. Zoerb, A.D. Hill, J.P. Schlegel and C.B. Harris, Organometallics, 31, 3980-3984 (2012).
"Ultrafast Studies of Stannae Activation by Triplet Organometallic Photoproducts" J.P. Lomont, S.C. Nguyen, and C.B. Harris, Organometallics, 31, 3947-3957 (2012).
"Observation of a Short-Lived Triplet Precursor in CpCo(CO)-Catalyzed Alkyne Cyclotrimerization" J.P. Lomont, S.C. Nguyen, M.C. Zoerb, A.D. Hill, J.P. Schlegel, and C.B. Harris, Organometallics, 31, 3582-3587 (2012).
"Ultrafast Observation of a Solvent Dependent Spin State Equilibrium in CpCo(CO)" J.P. Lomont, S.C. Nguyen, J.P. Schlegel, M.C. Zoerb, A.D. Hill, and C.B. Harris, J. Am. Chem. Soc., 134, 3120-3126 (2012).
"Time-resolved IR Studies on the Mechanism for the Functionalization of Primary C-H Bonds by Photoactivated Cp*W(CO)3(Bpin)" K.R. Sawyer, J.F. Cahoon, J.E. Shanoski, E.A. Glascoe, M.F. Kling, J.P. Schlegel, M.C. Zoerb, M. Hapke, J.F. Hartwig, C.E. Webster, and C.B. Harris, J. Am. Chem. Soc., 132, 1848-1859 (2010).
"Direct observation of photoinduced bent nitrosyl excited-state complexes" K.R. Sawyer, R.P. Steele, E.A. Glascoe, J.F. Cahoon, J.P. Schlegel, M. Head-Gordon, C.B. Harris, J. Phys. Chem. A, 112, 8505-8514 (2008).
"DFT and Time-resolved IR Investigation of Electron Transfer between Photogenerated 17- and 19-electron organometallic radicals" J.F. Cahoon, M.F. Kling, K.R. Sawyer, L.K. Andersen, C.B. Harris, J. Mol. Struct. (honor issue for F. Albert Cotton), 890, 328-338.