研究领域
Physical Chemistry/Spectroscopy and Dynamics of Gas-Phase Ions
Transition metal centers are ubiquitous in nature. They are abundant in interstellar space and are vital reaction sites in systems ranging from industrial catalysts to enzymes. We use a combination of mass spectrometry and laser photofragment spectroscopy to study the electronic and vibrational spectroscopy of gas-phase ions containing a metal (M) center, determining their bonding, structure and thermochemistry. We study two classes of molecules: organometallic ions such as PtCH2+ that are models for transition metal catalysis, and cluster ions such as Co(H2O)62+ that probe solvation of M2+.
Our experiments involve producing, selecting and photoexciting an ion and identifying its photodissociation products. We produce singly charged ions by laser ablation of a metal rod (to form M+), followed by ion-molecule reactions and cooling in a supersonic expansion to form a molecular beam. Multiply charged ions are generated by electrospray. Ions are injected into a reflectron time-of-flight mass spectrometer. A pulsed, tunable laser irradiates the mass-selected ion of interest in the reflectron and the masses of charged dissociation fragments are determined by their subsequent flight times to a detector. Monitoring fragment ion yield as a function of laser wavelength gives the photodissociation spectrum - the absorption spectrum of those ions that dissociate to give the product being monitored.
A practical scheme to convert methane to an easily transportable compound would greatly increase the utility of natural gas as an energy source. We study activation of methane and larger hydrocarbons by M+ and MO+ in the gas phase, where we can learn about the detailed reaction mechanism from the spectroscopy of the reaction intermediates, reactants and products. We also study the effect of the number and nature of solvent molecules on the absorption spectra of solvated M2+ and the interesting dissociation dynamics that occur when a multiply charged ion dissociates to two singly charged fragments. Electronic spectroscopy mostly gives information on excited electronic states, while vibrational spectroscopy is an ideal way to study the metal-ligand bond and how interactions with the metal affect bonds in the ligand, and we are developing new methods for measuring vibrational spectra of ions. Photoionization studies (at the Advanced Light Source) and calculations of the ground and excited electronic states complement the lab experiments.
近期论文
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"Spectroscopy of the Potential Energy Surfaces for C-H and C-O Bond Activation by Transition Metal and Metal Oxide Cations," Ricardo B. Metz, Adv. Chem. Phys., 138, 331-373 (2008) (invited review article)
"Optical Spectroscopy and Photodissociation Dynamics of Multiply Charged Ions," Ricardo B. Metz, Int. J. Mass Spectrom., 235, 131-143 (2004) (invited review article)
"Photofragment Spectroscopy of Covalently Bound Transition Metal Complexes: A Window into C-H and C-C Bond Activation by Transition Metal Ions," Ricardo B. Metz, Int. Rev. Phys. Chem., 23, 79-108 (2004) (invited review article)
Recent Research Papers:
"Near Ultraviolet Photodissociation Spectroscopy of Mn+(H2O) and Mn+(D2O)," Wright Lee Pearson III, Christopher Copeland, Abdulkadir Kocak, Zachary Sallese and Ricardo B. Metz, J. Chem. Phys., 141, Art. No. 204305 (9 pgs.) (2014)
"Vibrational Spectroscopy of Co+(CH4)n and Ni+(CH4)n (n=1-4)," Abdulkadir Kocak, Zachary Sallese, Michael D. Johnston and Ricardo B. Metz, J. Phys. Chem. A, 118, 3253-3265 (2014)
"VUV Photoionization Measurements and Electronic Structure Calculations of the Ionization Energies of Gas-Phase Tantalum Oxides TaOx (x=3-6)," Manori Perera, Kevin M. Roenitz, Ricardo B. Metz, Oleg Kostko and Musahid Ahmed, J. Spectrosc. Dyn., 4, Art. No. 21 (10 pgs.) (2014) link to journal download accepted version of paper
"Vacuum Ultraviolet Photoionization Studies of PtCH2 and H-Pt-CH3: A Potential Energy Surface for the Pt + CH4 Reaction," Manori Perera, Ricardo B. Metz, Oleg Kostko and Musahid Ahmed, Ang. Chemie Int. Ed., 52, 888-891 (2013)
"Dissociation Energy, Electronic and Vibrational Spectroscopy of Co+(H2O) and Its Isotopomers," Abdulkadir Kocak, Geoff Austein-Miller, Wright L. Pearson III, Gokhan Altinay and Ricardo B. Metz, J. Phys. Chem. A, 117, 1254-1264 (2013) (Peter B. Armentrout Festschrift)
"Photodissociation Studies of the Electronic and Vibrational Spectroscopy of Ni+(H2O)," Jennifer S. Daluz, Abdulkadir Kocak and Ricardo B. Metz, J. Phys. Chem. A, 116, 1344-1352 (2012)
"Microsolvation of Co2+ and Ni2+ by Acetonitrile and Water: Photodissociation Dynamics of M2+(CH3CN)n(H2O)m," Manori Perera, Paul Ganssle and Ricardo B. Metz, Phys. Chem. Chem. Phys., 13, 18347-18354 (2011)
"Electronic and Vibrational Spectroscopy of Intermediates in Methane-to-Methanol Conversion by CoO+," Gokhan Altinay, Abdulkadir Kocak, Jennifer Silva Daluz and Ricardo B. Metz, J. Chem. Phys., 135, 084311 (10 pgs.) (2011)
"Vibrational Spectroscopy and Theory of Fe+(CH4)n (n=1-4)," Murat Citir, Gokhan Altinay, Geoff Austein-Miller and Ricardo B. Metz, J. Phys. Chem. A, 114, 11322-11329 (2010)
"Comparison of IRMPD, Ar-tagging and IRLAPS for Vibrational Spectroscopy of Ag+(CH3OH)," Gokhan Altinay and Ricardo B. Metz, Int. J. Mass Spectrom. 297, 41-45 (2010)
"Vibrational Spectroscopy of Intermediates in Methane-to-Methanol Conversion by FeO+," Gokhan Altinay, Murat Citir and Ricardo B. Metz, J. Phys. Chem. A, 114, 5104-5112 (2010)
"Vibrational Spectroscopy of Intermediates in Benzene-to-Phenol Conversion by FeO+," Gokhan Altinay and Ricardo B. Metz, J. Am. Soc. Mass Spectrom., 21, 750-757 (2010)
"Photodissociation Spectroscopy and Dissociation Dynamics of TiO+(CO2)," K. Manori Perera and Ricardo B. Metz, J. Phys. Chem. A, 113, 6253-6259 (2009)
"Vacuum-Ultraviolet Photoionization Measurement and ab Initio Calculation of the Ionization Energy of Gas-Phase SiO2" Oleg Kostko, Musahid Ahmed and Ricardo B. Metz, J. Phys. Chem. A, 113, 1225-1230 (2009)
"Direct Determination of the Ionization Energies of PtC, PtO and PtO2 with VUV Radiation," Murat Citir, Ricardo B. Metz, Leonid Belau and Musahid Ahmed, J. Phys. Chem. A, 112, 9584-9590 (2008)
"Mode Selective Photodissociation Dynamics in V+(OCO)," Murat Citir and Ricardo B. Metz, J. Chem. Phys., 128, 024307 (10 pages) (2008)
"Electronic and Vibrational Spectroscopy and Vibrationally Mediated Photodissociation of V+(OCO)," Murat Citir, Gokhan Altinay and Ricardo B. Metz, J. Phys. Chem. A, 110, 5051-5057 (2006)
"Direct Determination of the Ionization Energies of FeO and CuO with VUV Radiation," Ricardo B. Metz, Christophe Nicolas, Musahid Ahmed and Stephen R. Leone, J. Chem. Phys., 123, 114313 (6 pages) (2005)
"Electronic Spectroscopy and Photodissociation Dynamics of Co2+-Methanol Clusters: Co2+(CH3OH)n (n = 4-7)," Christopher J. Thompson, Kieron P. Faherty, Kay L. Stringer and Ricardo B. Metz, Phys. Chem. Chem. Phys., 7, 814-818 (2005)
"Photofragment Spectroscopy of Pi Complexes: Au+(C2H4) and Pt +(C2H4)," Kay L. Stringer, Murat Citir and Ricardo B. Metz, J. Phys. Chem. A, 108, 6996-7002 (2004)
"Energies and Wavefunctions for Several One-Dimensional Potentials," Ricardo B. Metz, J. Chem. Educ., 81, 157 (2004) (MathCAD module for use with Physical Chemistry or Introductory Quantum Mechanics, also see the MathCAD in Physical Chemistry website)
"The Low-Lying Electronic States of FeO+: Rotational Analysis of the Resonance Enhanced Photodissociation Spectra of the 6P7/2 <- X6S+ System ," Fernando Aguirre, John Husband, Christopher J. Thompson, Kay L. Stringer and Ricardo B. Metz, J. Chem. Phys. 119, 10194-10201 (2003)
"Electronic Spectroscopy of Predissociative States of Platinum Oxide Cation ," Christopher J. Thompson, Kay L. Stringer, Melanie McWilliams and Ricardo B. Metz, Chem. Phys. Lett. 376, 588 -594 (2003)
"Salt-Bridge Transition State for the Charge Separation Co2+(H2O)4 -> CoOH+(H2O)2 + H3O+," Martin K. Beyer and Ricardo B. Metz, J. Phys. Chem. A, 107, 1760-1762 (2003).
"Electronic Spectroscopy of Intermediates Involved in the Conversion of Methane to Methanol by FeO+," Fernando Aguirre, John Husband, Christopher J. Thompson, Kay L. Stringer and Ricardo B. Metz, J. Chem. Phys. 116, 4071-4078 (2002)
"Methane-to-Methanol Conversion by Gas-Phase Transition Metal Oxide Cations: Experiment and Theory," Ricardo B. Metz, in Research Advances in Physical Chemistry Vol. 2, R. M. Mohan, Ed., Global, Trivandrum, India, pp. 35-43 (2001) (invited book chapter)
"Electronic Spectroscopy and Photodissociation Dynamics of Hydrated Co2+ Clusters: Co2+(H2O)n (n = 4-7)," Kieron P. Faherty, Christopher J. Thompson, Fernando Aguirre, Jodi Michne and Ricardo B. Metz, J. Phys. Chem. A, 105, 10054-10059 (2001).
"Photodissociation Spectra of Transition Metal Sulfides: Spin-Orbit Structure in Charge Transfer Bands of FeS+ and NiS+," John Husband, Fernando Aguirre, Christopher J. Thompson and Ricardo B. Metz, Chem. Phys. Lett. 342, 75-84 (2001).
"Photofragment Spectroscopy and Dynamics of NiOH+ and NiOH+(H2O)," Christopher J. Thompson, Fernando Aguirre, John Husband and Ricardo B. Metz, J. Phys. Chem. A 104, 9901-9905 (2000).
"Photodissociation Dynamics of Hydrated Ni2+ Clusters: Ni2+(H2O)n (n = 4-7)," Christopher J. Thompson, John Husband, Fernando Aguirre and Ricardo B. Metz, J. Phys. Chem. A 104, 8155-8159 (2000).
"Photofragment Spectroscopy of FeCH2+, CoCH2+, and NiCH2+ near the M+-CH2 Dissociation Threshold," John Husband, Fernando Aguirre, Christopher J. Thompson, Christopher M. Laperle and Ricardo B. Metz, J. Phys. Chem. A 104, 2020-2024 (2000).
"Gas-phase Photodissociation of AuCH2+: the Dissociation Threshold of Jet-Cooled and Rotationally Thermalized Ions," Fernando Aguirre, John Husband, Christopher J. Thompson and Ricardo B. Metz, Chem. Phys. Lett. 318, 466-470 (2000).
"Vibrationally Resolved Photofragment Spectroscopy of FeO+," John Husband, Fernando Aguirre, Peter Ferguson and Ricardo B. Metz, J. Chem. Phys. 111, 1433-1437 (1999).
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