Tibetts

Katharine Tibbetts, Ph.D.

Assistant Professor
kmtibbetts@vcu.edu
(804) 828-7515
Oliver Hall 4020

Education

A.B., Princeton University, 2005
Ph.D., Princeton University, 2012
Graduate Intern, Sandia National Laboratories, 2011
Postdoctoral Fellow, Temple University, 2012-2015

Honors and Awards

National Science Foundation Graduate Research Fellowship, 2006-2009.
Centennial Fellowship, Princeton University, 2006-2011.
Hubert Alyea Teaching Award, Princeton University, 2008.
Fulbright Fellowship in Germany, 2005-2006.

Research interests

Tibbetts group investigates chemical reactions induced by strong-field femtosecond laser excitation of gas- and condensed-phase molecules. The short time duration (~10-14  s) and high electric field strength (~5 V/Å) of femtosecond laser pulses make them ideal for both inducing nonequilibrium chemical transformations and probing reaction dynamics in real time. Current research areas focus on (1) synthesizing metal-based nanoparticles from metal salt precursors and elucidating reaction mechanisms for these transformations in the condensed phase, and (2) probing and controlling the dissociation dynamics of polyatomic radical cations in the gas phase.

1. Synthesis of metal and composite nanoparticles

Metal nanoparticles with tailored sizes possess many unique optical and electronic properties that make them useful for applications such as catalysis and sensing. While many chemical synthetic routes to these types of nanomaterials exist, femtosecond laser reduction of metal salt precursors has the advantages of avoiding the use of environmentally damaging reducing agents and organic surfactants that can limit the practical use of the resulting materials. Combining metal-salt reduction with laser ablation of a target surface (e.g., a Si wafer) immersed in the solution enables the synthesis of metal-oxide composite nanomaterials with metastable phases. Current projects involve determining the effects of added salts and radical scavengers on the reduction kinetics of [AuCl4]- and size of the resulting Au nanoparticles, synthesizing ultrasmall M@SiOx nanocomposites (M=Au, Pd) as CO oxidation catalysts, and synthesizing Au- and Ag-doped laser-induced periodic surface structures (LIPSS) on Si for surface-enhanced Raman spectroscopy (SERS) sensing applications. Future work will focus on extending these synthetic techniques to earth-abundant metals such as Fe, Co, and Ni.

2. Dissociation dynamics of gas-phase polyatomic radical cations

Determining unimolecular dissociation mechanisms of radical cations is important to understand fundamental processes including ionizing radiation-induced DNA damage and initial energy release pathways in energetic molecules. Femtosecond time-resolved “pump-probe” measurements can follow these dissociation reactions on their natural timescales. Combined with quantum-chemical calculations of cationic electronic potential energy surfaces and reaction intermediates, these measurements can determine the reaction mechanisms with exquisite detail. Current projects focus on the reactions of organic phosphonates and phosphates as models for the DNA sugar-phosphate backbone and nitrotoluenes as models for nitroaromatic explosives. Future work will explore model systems for the deoxyribose sugar and nucleobases, as well as high-nitrogen content energetic molecules such as tetrazoles.

Publications

Publications at VCU

D. Ampadu Boateng and K. M. Tibbetts, “Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization” J. Vis. Exp. 2018, e58263

D. Ampadu Boateng, G. L. Gutsev, P. Jena, and K. M. Tibbetts, “Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C-NO 2 bond homolysis” J. Chem. Phys. 2018, 148, 134305

V. K. Meader, M. G. John, L. M. Frias Batista, S. Ahsan, and K. M. Tibbetts, “Radical Chemistry in a Femtosecond Laser Plasma: Photochemical Reduction of Ag+ in Liquid Ammonia Solution” Molecules 2018, 23, 532

D. Ampadu Boateng, G. L. Gutsev, P. Jena, and K. M. Tibbetts, “Ultrafast Coherent Vibrational Dynamics in Dimethyl Methylphosphonate Radical Cation” Phys. Chem. Chem. Phys. 2018, 20, 4636-4640

G. L. Gutsev, D. Ampadu Boateng, P. Jena, and K. M. Tibbetts, “A Theoretical and Mass Spectrometry Study of Dimethyl Methylphosphonate: New Isomers and Cation Decay Channels in an Intense Femtosecond Laser Field” J. Phys. Chem. A 2017, 121, 8414-8424

V. K. Meader, M. G. John, C. J. Rodrigues, and K. M. Tibbetts, “Roles of Free Electrons and H 2 O 2 in the Optical Breakdown-Induced Photochemical Reduction of Aqueous [AuCl4] ” J. Phys. Chem. A 2017, 121, 6742-6754

K. M. Tibbetts, X.-J. Feng, and H. Rabitz, “Exploring experimental fitness landscapes for chemical synthesis and property optimization” Phys. Chem. Chem. Phys. 2017, 19, 4266-4287

Selected publications from postdoctoral and graduate work

K. M. Tibbetts, B. Tangeysh, J. H. Odhner, and R. J. Levis, “Elucidating Strong Field Photochemical Reduction Mechanisms of Aqueous [AuCl4] : Kinetics of Multiphoton Photolysis and Radical-Mediated Reduction” J. Phys. Chem. A 2016, 120, 3562-3569

K. M. Tibbetts, M. Tarazkar, T. Bohinski, D. A. Romanov, S. Matsika, and R. J. Levis, “Controlling the Dissociation Dynamics of Acetophenone Radical Cation Through Excitation of Ground and Excited State Wavepackets” J. Phys. B: Opt. At. Mol. Phys. 2015, 48, 164002

B. Tangeysh, K. M. Tibbetts, J. H. Odhner, B. B. Wayland, and R. J. Levis, “Triangular Gold Nanoplate Growth by Oriented Attachment of Au Seeds Generated by Strong Field Laser Reduction” Nano Lett. 2015, 15, 3377-3382

T. Bohinski, K. M. Tibbetts, M. Tarazkar, D. A. Romanov, S. Matsika, and R. J. Levis, “Strong Field Adiabatic Ionization Prepares a Launch State for Coherent Control” J. Phys. Chem. Lett. 2014, 5, 4305-4309

K. M. Tibbetts, T. Bohinski, K. Munkerup, M. Tarazkar, and R. J. Levis, “Controlling Dissociation of Alkyl Phenyl Ketone Radical Cations in the Strong Field Regime through Hydroxyl Substitution Position” J. Phys. Chem. A 2014, 118, 8170-8176

B. Tangeysh, K. M. Tibbetts, J. H. Odhner, B. B. Wayland, and R. J. Levis, “Gold Nanoparticle Synthesis Using Spatially and Temporally Shaped Femtosecond Laser Pulses: Post-Irradiation Auto-Reduction of Aqueous [AuCl4] ” J. Phys. Chem. C 2013, 116, 18719-18727

T. Bohinski, K. M. Tibbetts, M. Tarazkar, D. A. Romanov, S. Matsika, and R. J. Levis, “Measurement of an Electronic Resonance in a Ground-State, Gas-Phase Acetophenone Cation via Strong-Field Mass Spectrometry” J. Phys. Chem. Lett. 2013, 4, 1587-1591

K. M. Tibbetts, X. Xing, and H. Rabitz, “Exploring Control Landscapes for Laser-Driven Molecular Fragmentation” J. Chem. Phys. 2013, 139, 144201

K. M. Tibbetts, X. Xing, and H. Rabitz, “Optimal Control with Homologous Families of Photonic Reagents and Chemical Substrates” Phys. Chem. Chem. Phys. 2013, 15, 18012-18022

K. W. Moore, A. Pechen, X.-J. Feng, J. Dominy, V. Beltrani, and H. Rabitz, “Why is Chemical Synthesis and Property Optimization Easier than Expected?” Phys. Chem. Chem. Phys. 2011, 13, 10048-10070

K. W. Moore, A. Pechen, X.-J. Feng, J. Dominy, V. Beltrani, and H. Rabitz, “Universal Characteristics of Chemical Synthesis and Property Optimization” Chem. Sci. 2011, 2, 417-424