News and Events!
Bowers Group meetings are held each Friday at 10:45am in NPB 2260. Visitors are welcome!
Update coming soon... Lot's of exciting developments on parahydrogen induced polarization (PHIP), spin exchange optical pumping (SEOP), and optically pumped NMR (OPNMR).
October 3, 2012: Congratulations to Ronghui and Muslim for being selected to present oral presentations at the Southeastern Meeting of the American Chemical Society, SEMRC Symposium, to be held in Raleigh N.C., November 14-17.
• Hyperpolarized Aldehyde Through Spontaneous Polarization Transfer from Parahydrogen, Ronghui Zhou, Daniel Schulman, Clifford R. Bowers..
• Anomalous Molecular Transport Properties in Nanotubular Materials: New Insights from NMR Experiments, Muslim Dvoyashkin, Michael F. Greer, Aiping Wang, Hrishi Bhase, Linda S. Shimizu, Sergey Vasenkov, and Clifford R. Bowers.
September 18, 2012: Congratulations to graduate student Hrishi Bhase for passing his Oral qualifying exam for the Ph.D.!
August 23, 2012: Testing with Optigrate's volume Bragg holographic grating spectrally narrowed laser diode array in spin exchange optical pumping experiments is underway.
August 15, 2012: Russ Bowers returned from sabbatical at Radboud University, Nijmegen, Netherlands. The sabbatical visit was supported by a grant from Netherlands Organization for Science.
• Evidence of Single-File Diffusion from Pulsed Field Gradient NMR in Combination with Hyperpolarized Xe-129 NMR, Institute of Molecules and Materials, Radboud University, Netherlands, August 13, 2012.
• Evidence of Single-File Diffusion from Pulsed Field Gradient NMR in Combination with Hyperpolarized Xe-129 NMR, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, July 30, 2012.
• Time-Scaling of Xe Diffusion in Nanotubular Structures by Pulsed Field Gradient NMR in Combination with Hyperpolarized Xe-129 NMR, Xenon in Materials (XeMAT 2012), Dublin, June 27-29, 2012.
• Hyperpolarized Tracer Exchange NMR in Nanotubular Materials, Chemistry Department, Southampton University, UK, May 24, 2012.
• Signal Enhancement Utilizing Parahydrogen, Institute of Molecules and Materials, Radboud University, Netherlands, April 25, 2012.
July 3rd, 2012: Congratulations to Chris Akel for successfully defening his Master's thesis, entitled "Xenon-129 NMR Studies of Gas Adsorption Dynamics in Crystalline Nanotube Materials."
New Papers published:
M. Dvoyashkin, J. Zang, G.I. Yucelen, A. Katihar, S. Nair, D.S. Sholl, C.R. Bowers, and S. Vasenkov, Diffusion of Tetraﬂuoromethane in Single-Walled Aluminosilicate Nanotubes: Pulsed Field Gradient NMR and Molecular Dynamics Simulations, J. Phys. Chem. C., in press (2012).
C.R. Bowers, Y. Wei, B.S. Aitken, C.R. Reeg, C.D. Akel, K.B. Wagener, Molecular dynamics in precision deuteriomethyl branched polyethylene from solid-state deuterium NMR, Polymer, 53, 2633-2642 (2012).
K. Glass, S. Ito, P.R. Wilby, T. Sota, A. Nakamura, C.R. Bowers, J. Vinther, S. Dutta, R. Summons, D. E. G. Briggs, K. Wakamatsu, J. D. Simon, Chemical Evidence for Eumelanin from the Jurassic Period, Proc. Natl. Acad. Sci. USA, 109, 10218-10223 (2012).
New funding received:
• 2012-2014, American Chemical Society Petroleum Research Foundation New Direction Grant, Parahydrogen Enhanced NMR Studies of Heterogeneous Hydrogenation on Supported Metal Particles.
• 2012-2014, National High Magnetic Field Laboratory User Collaborative Grant Program, Optical NMR Probes for High Field Optically Pumped NMR Spectroscopy in Semiconductor Quantum Structures.
April 18th: Chris Reeg presented his honors thesis in physics, entitled "Solid-State Deuterium NMR Study of Methyl Rotation in Precisely Branched Polyethylenes." Chris' thesis earned the "highest honors" distinction, and was selected for this year's Undergraduate Thesis Award, which comes with a cash prize. This accomplishment will be recognized at the Physics Department Reception on April 29th. Congratulations Chris!
The group is expanding! Check out our most recent group photo, at left.
Hans Jakobsen, who is visiting from Aarhus University, Denmark, is collaborating with us on several projects involving solid-state quadrupolar NMR. We have a manuscript in preparation, entitled "Quantitative analysis of powdered polycrystalline Na24Si136 and Na8Si46 by solid-state 23Na MAS NMR spectroscopy," which involoves a collaboration with George Nolas of the University of South Florida Physics Department.
Ronghui Zhou earned his Master's in Chemistry while studying in Korea. Ronghui is now a first his first student who plans to qualify in the Physical Chemistry Division. Though he has been extremely busy with teaching, taking classes, and cumes, he has managed to get a great start on his new research project involving NMR signal enhancement with parahydrogen on surfaces.
Hrishi Base is a second year Analytical Division graduate student who transferred to our group after receiving his Master's in Chemistry. His new project will involve application of hyperpolarized xenon-129 NMR to characterize supported phospholipid bilayers systems.
Celeste Kennard is a 4th year undergraduate majoring in Chemical Engineering. She is designing and building a new low temperature probe to facilitate NMR studies of porous materials under continuous gas flow conditions.
Alex Titov is an undergraduate Chemical Engineering major who is working on the automation of various types of experiments/processes using National Instruments LabView software.
Seung Y Lee is an enthusiastic Freshman Chemistry major who has been attending our group meetings. Seung will join one or more research projects this Summer.
Ryan wood presented a Physical Chemistry Division seminar entitled "Power Dependence of Optically Induced Nuclear Spin Polarization in Semiconductors." Next comes his qualifying exam on March 1st.
We are delighted that Dr. Muslim Dvoyashkin has joined us as an NSF supported postdoctoral associate. Muslim earned his Ph.D. in Physics at the University of Leipzig, Germany.
The CHM6430 and CHM6470 final exams are scheduled for December 7th and 8th (respectively).
Nov. 19th. Congratulations to Satyajit Phadke for passing his Ph.D. final defense! Satyajit is a collaborating student from the research group of Prof. Juan Nino in the UF Department of Materials Science.
Our latest paper, "Hyperpolarized NMR in Single-File Nanotubes," by C.R. Bowers, C.-Y Cheng, T. C. Stamatatos and G. Christou, has been accepted for publication in the AIP Conference Proceedings of the MRPM-10.
Oct 22-24: The 39th Southeastern Magnetic Resonance Conference was held at the University of Florida. Bowers presented an invited talk at the meeting.
Sept. 12-16: Bowers presented an invited talk at the 10th Bologna Conference on Magnetic Resonance in Porous media (MRPM 10) in Leipzig, Germany. The conference was held in the Physics Building, shown below.
Aug. 9th: Professor Lucio Frydman of the Weizmann Insitute visited UF and presented a seminar entitled “NMR, MRI & EPR Coming Together in the Aid of Structure Elucidation: Ultrafast, Ultrasensitive Multidimensional Magnetic Resonance Spectroscopy.”
We congratulate collaborating student Yuying Wei, of the Wagener group, for successfully passing her Ph.D. final exam! Thesis title: "Understanding Precision Polyolefins by Solid State NMR Spectroscopy and x-ray scattering.
Congratulations to Amrish Menjoge, a graduate student with Prof. Sergey Vasenkov, who successfully defended his Ph.D. thesis! Amrish's thesis is entitled "Relationship between diffusion and structure in selected nanostructured systems by NMR." Amrish has collaborated with us on hyperpolarized xenon-129 2D Exchange NMR experiments examining gas re-adsorption effects in zeolites. The Vasenkov and Bowers groups got together to celebrate the occassion at the Gainesville Ale House. Congratulations Amrish, and best wishes for success in your new position!
Apr 18-23. The group attended the 51st Experimental NMR Conference (ENC). We stayed at a private condo adjacent to the conference venue at the Daytona Beach Hilton Oceanfront hotel.
This will be the first ENC for everyone except Dr. Bowers. He attended his first ENC meeting in 1987 where he and Dan Weitekamp (recipient of the 2009 Laukien Prize) presented a poster presenting the first experimental demonstration of the PASADENA (Parahydrogen and Synthesis Allow Dramatically Enhanced Nuclear Alignment) effect .
Dr. Bowers will make an oral presentation at the ENC entitled "Origin of the "Dispersion-Like" Lineshape in Resistively Detected NMR in the Quantum Hall Effect: Evidence of the Skyrme Crystal?" It will also be presented as a poster. abstract Dr. Bowers, together with co-authors Chi-Yuan Cheng, Theocharis Stamatatos, and George Christou, will also present a poster entitled "Control of the Diffusion Time-Scaling in Molecular Wheel Nanotubes as Detected by Continuous-Flow Hyperpolarized Xenon-129 NMR". abstract
Congratulations to Christopher Reeg for receiving the prestigious Barry M. Goldwater Scholarship. Chris, a junior year physics major, joined our group in Spring 2009. Using solid-state deuterium NMR, he is measuring methyl group rotational activation energies to probe chain packing in the precisely methyl branched polyethylenes. The project is a collaboration with Yuying Wei and Professor Ken Wagener. Chris will participate in the NSF REU program at Cornell University this summer.
David Richardson, a student with Dr. Wallace Brey, successfully defended his Ph.D. thesis,entitled "THE RELATIVE SIGNS OF COUPLING CONSTANTS IN FLUORINATED CYCLOPROPANES AND THE AGGREGATION OF AMYLOID-BETA (25-35) PEPTIDE". He will graduate in May. Congratulations David!
Judith Wollbrett-Blitz, a student at the Universite Pierre et Marie Curie, will join our lab for Summer 2010 as part of the NSF UF-France REU program. Welcome Judith!
Ryan Wood presented a seminar to the Physical Chemistry Division on Tuesday, April 6th. Well done Ryan!
Classes end April 21st.
Our paper, entitled " Molecular Wheels as Nanoporous Materials: Differing Modes of Gas Diffusion through Ga10 and Ga18 Wheels Probed by Hyperpolarized 129Xe NMR Spectroscopy," by C.-Y Cheng, T. C. Stamatatos, G. Christou, and C.R. Bowers, has appeared as an ASAP article in the J. Am. Chem. Soc.
Our paper, entitled "Resistively detected NMR of the ν=1 quantum Hall state: A tilted magnetic field study," by C.R. Bowers, G. M. Gusev, J. Jaroszynski, J.L. Reno, J.A. Simmons has appeared in Phys. Rev. B.
Our PRB paper was selected for the Virtual Journal of Nanoscale Science and Technology.
Classes begin! Dr. Bowers is teaching CHM6461, Statistical Thermodynamics. There are four registered students and two auditors.
Caroline Pointer-Keenan successfully defended her Ph.D. thesis. She is now a postdoctoral associate with Prof. Jurgen Senker at the Universität Bayreuth, Germany.
(i) Advanced Nuclear Magnetic Resonance (NMR) spectroscopy techniques in solids, liquids and gases; (ii) Optically pumped NMR, Spin-Exchange Optical Pumping, Dynamic Nuclear Polarization, Parahydrogen Induced Polarization; Electrical detection of NMR and ESR; (iii) Applications of NMR to energy-related materials, including MOFs, nanoporous and nanotubular materials; (iv) Heterogeneous and homogeneous hydrogenation catalysis; (v) Applications of optically pumped NMR to nanoscale phenomena in inorganic semiconductors; (vi) Molecular transport in nanoporous and nanotubular materials.
Our lab and offices are located within the UF Physics Building.
Prof. Bowers is affiliated with the National High Magnetic Field Laboratory and the UF Center for Condensed Matter Sciences.
Bowers Research Group, Univesity of Florida, Department of Chemistry (June 2013)
Overview. Nuclear magnetic resonance (NMR) is a versatile form of spectroscopy in which radiowaves are absorbed or emitted due to nuclear spin flips. It is used widely by chemists, physicists, biologists and engineers to obtain structural and dynamical information in molecules and materials of all sorts. However, the radiofrequency quanta involved in nuclear spin flips are typically much smaller than the thermal energy, rendering NMR useless for many applications. A common theme of our research is the development and application of NMR signal enhancement methods. We apply advanced NMR techniques to a variety of solid-state materials and chemical compounds. On the theoretical side, we employ density matrix/operator calculations, quantum mechanics, statistical mechanics, and numerical simulations to help us discover and analyze new or anomalous phenomena.
Research Opportunities. There are research opportunities in our lab for students at all levels, particularly in (but not necessarily limited to) the areas of physics, physical chemistry/chemical physics, analytical and materials chemistry. Please contact us (firstname.lastname@example.org) for more information or to schedule a lab tour or to attend a meeting.
Currently Funded Projects.
(1) Heterogeneous Catalysis. Hydrogenation reactions on supported metals like Pd and Pt are crucial to industry, yet the mechanism of catalysis, even for simple substrates such as ethylene, are not well understood. Parahydrogen induced nuclear polarization (PHIP), which exploits the quantum mechanical properties of the spin isomers of H2 in hydrogenation reactions, is an established tool for the study of homogeneous hydrogenation reactions catalyzed by transition metal complexes in solution. PHIP-NMR studies are aimed at determining the factors governing the pairwise proton transfer pathway of hydrogenation, wherein the two H atoms of the same H2 molecule are added to the same substrate molecule to yield the product. Specifically, the Pd particle shape and size and morphology of the support material will be investigated. The PHIP signal amplification will be exploited to search for possible reaction intermediates and to study the kinetics of heterogeneous hydrogenation catalysis. Funded by PRF#52258-ND5 (2012-2014).
(2) Molecular transport in nanotubular materials. Molecular transport properties in nanotubular materials become particularly interesting when the cross-sectional dimensions are comparable to those of the sorbate, where due to steric interactions, diffusive dynamics may become collective. Validation of theoretical models for single-file or center-of-mass diffusion in such systems has been impaired by the lack of reliable experimental data in sufficiently ideal systems. We are using hyperpolarized 129Xe NMR and pulsed field gradient NMR techniques to characterize diffusion in a wide range of nanotubular materials. Also of interest is the case of two or more sorbate components, where one component may change the diffusion time-scaling of the smaller sorbate. Despite the potential importance of such processes to the chemical industry, cuch systems have not been approached experimentally up to now. Funded by NSF CHE-0957641 (2010-2013).
(3) Optically pumped NMR in semiconductor nanostructures. This project involves NMR spectroscopy under conditions of in-situ optical irradiation in high DC magnetic fields and cryogenic temperatures (down to ~1.5 K). The optical pumping effect provides NMR signal amplification which can exceed a factor of 104 in III-V semiconductors such as GaAs and InP, thereby extending the applicability of NMR to nanostructured systems that would otherwise be out-of-reach. Optically pumped NMR (OPNMR) spectroscopy, whereby the OPNMR signal is recorded as a function of the pump laser energy, is a hitherto underutilized probe of electronic structure and conduction electron spin dynamics. The research plan includes the following initiatives: (a) measurement of the detailed energy band structure, including spin, and its correlation to OPNMR photon energy dependence; (b) optical pumping in the vicinity of level crossings as a means of extending OPNMR to very high magnetic field; (c) the proof-of-principle demonstration of time-resolved OPNMR as a new technique for probing electron spin dynamics. Funded by NMHFL-UCGP (2012-2014).
|Hyperpolarized Xenon-129 NMR|
Studying Single-File Diffusion and Gas Exchange in L-Alanyl-L-Valine Nanotubes
SEM of AV Crystals
Hyperpolarized Xe-129 EXSY and Single-File Diffusion in Ga-Wheels
|JACS, in press.|
Solid-State NMR in Precisely Branched Polymers
Rotator phase just below melting point of PE with CD3 branches every 15 carbons, as observed by deuterium NMR. http://dx.doi.org/10.1002/ange.200900377
Resistively Detected NMR in the Quantum Hall Effect
9.4T Bruker Avance 400MHz Solid-State NMR Spectrometer
|Oxford 7T Home-built Spectrometer|
Oxford 10T Top-Loading Helium-3 Cryostat and Our Friends from Oxford Instruments
Home-built Rb-Xe Spin-Exchange
Optical Pumping System
National High Magnetic Field Laboratory, Tallahassee
Microwave Irradiation at high B/T
Fall 2010: CHM6470, Chemical Bonding and Spectra I
Fall 2010: CHM6430, Thermodynamics
Spring 2010: CHM6461, Introduction to Statistical Thermodynamics
Fall 2009: CHM6580, Special Topics, Nuclear Magnetic Resonance: Theory and Practice
Spring 2009: CHM4411 (section 5034), Physical Chemistry I
Fall 2008: CHM6430, Thermodynamics
Spring 2008: CHM6461, Introduction to Statistical Thermodynamics
Fall 2007: CHM4411L, Physical Chemistry Lab
Fall 2006: CHM4411L, Physical Chemistry I: Thermo and Kinetics
Summer A 2006: CHM4411, Physical Chemistry I: Thermo and Kinetics
Spring 2006: CHM4411, Physical Chemistry I: Thermo and Kinetics
Fall 2005: CHM4411L, Physical Chemistry Lab
Spring 2005: CHM6490, Introduction to Spectroscopy
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Clifford Russell Bowers
2360 New Physics Building
Ph.D., California Institute of Technology, Pasadena, California. Advisor: Daniel P. Weitekamp. Thesis: "Parahydrogen and Synthesis Allows Dramatically Enhanced Nuclear Alignment" (see “Sensitivity Enhancement Utilizing Parahydrogen,” in Encyclopedia of Nuclear Magnetic Resonance: Supplementary Volume, John Wiley & Sons, Ltd (2002), pp. 750-770 ).
B.A. Chemistry, Bowdoin College, Brunswick, Maine, Summa Cum Laude in Chemistry.
2000-present. Associate Professor (tenured) of Chemistry and Associate Affiliate Professor of Physics, University of Florida, Gainesville.
1994-2000. Assistant Professor, Department of Chemistry, University of Florida, Gainesville.
1992-1993. Postdoctoral Fellow, Chemistry Department, University of California, Berkeley. Advisor: Alexander Pines.
1990-1991. NATO-NSF Postdoctoral Fellow, 2nd Institute of Physics, University of Stuttgart, Germany. Photon-alkali metal atom interactions in optically detected magnetic resonance. Advisor: Michael Mehring.
Graduate Research Assistant, Chemistry Department, California Institute of Technology, Pasadena, California. Advisor: Daniel P. Weitekamp.
Summer Undergraduate Researcher, Chemistry Department, Harvard University, Cambridge, Massachusetts. "Application of Information Theory to Genetic Sequences," Advisor: Dudley R. Herschbach.
Affiliations and Activities
Division of Physical Chemistry, University of Florida.
Faculty affiliate of the UF Department of Physics.
Materials Research Society.
American Physical Society.
Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Lab.
Executive Committee, Center for Condensed Matter Sciences, University of Florida.
Center for Chemical Physics, University of Florida.
Chair, Committee on Instruction, UF Chemistry Department.
Physical Chemistry Division Seminar Coordinator, Fall 2009, 2007,2006,2005.
Software utilities for use in Windows (xp, vista, 7) or Linux.
These uility programs are provided free of charge, but come with absolutely no warranty.
Unfortunately, the way Bruker's xwinnmr program stores 1D specta and fids is extremely inconvenient if you are interested in importing a large number of 1D spectra into other programs, such as DFP, Mathematica, Excel or Igor. The utilities bruk2dfp.exe and ifid.exe provide a solution to this quandry.
bruk2dfp.exe is a Windows console application for batch conversion of Bruker Xwinnmr 1r binary spectrum files (SGI Irix, little endian to big endian conversion) to any one of four user specified output formats : Igor Pro text files, DFP input files, 2-column text files, or Mathematica lists (suitable for use with ListPlot3D). Here is the source code: bruk2dfp.c. Please email email@example.com if you find bugs.
For use in Windows 7, installation of cygwin is recommended. Run bruk2dfp as a command line program in a bash shell. The bash shell will give you access to other unix utilities, such as "find".
Some crude applciation notes are given in the readme file.
Bruk2dfp reads a list of bruker "1r" files to be converted. The list can be created using the unix "find command". For example, if my experiment directory is named wag21d-rt, I would want to gather all the "1r" spectrum filenames (with complete path specification) and put them into a text file named list.txt within the wag21d-rt directory. This is done as follows:
find wag21d-rt -name "1r" > wag21d-rt/list.txt
ifid.exe is for bulk conversion of Bruker fids into ascii text files. Here is the source code: ifid.c. This program reads a list of bruker "fid" files to be converted. The list can be created using the unix "find command". For example,
find wag21d-rt -name "fid" > wag21d-rt/list.txt
would create a file named "list.txt" containing a list of "fid" files in the target directory, e.g. wag21d-rt. If necessary, the program converts from little endian to big endian format after reading the binary "fid" file suitable for intel x86 processors. The program reads the acqus files to obtain the dwell time. ifid.exe should be executed in the same folder as the list.txt file (without any command line argument), or alternatively, folder containing the "list.txt" can be specified as a command line argument.
mathnmrv6.nb is a Mathematica notebook file containing a collection of modules for NMR signal processing. The routines were specifically designed for interpolation, left shifting, phasing, and fourier transformation of Bruker fids. An example of data processing (deuterium quadrupole echo signals) is given here.
dfp2igor (source code: dfp2igor.c) is a utility program for converting the DFP output files into stacked spectra in Igor Pro text files. This program is useful If you are manually processing DFP output spectra with Igor Pro.