Broadband Rotational Spectroscopy Raymond C. Ferguson interview for the Beckman Center for the History of Chemistry Brooks H. Pate Department of Chemistry University of Virginia http://faculty.virginia.edu/bpate- E. Bright Wilson, Jr (1986) “You said earlier that microwave hasn’t played the role that NMR has. Of course it’s nowhere near playing the role that NMR does. It’s a little hard to say what should have been done, but we could have done better. Still, it’s a marvelous tool, and I
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Broadband Rotational Spectroscopy Raymond C. Ferguson interview for the Beckman Center for the History of Chemistry Brooks H. Pate Department of Chemistry.
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Broadband Rotational Spectroscopy
Raymond C. Ferguson interview for the Beckman Center for the History of Chemistry
Brooks H. PateDepartment of Chemistry
University of Virginia
http://faculty.virginia.edu/bpate-lab/
E. Bright Wilson, Jr (1986)
“You said earlier that microwave hasn’t played the role that NMR has. Of course it’s nowhere near playing the role that NMR does. It’s a little hard to say what should have been done, but we could have done better. Still, it’s a marvelous tool, and I still love it, quite frankly. I wish I could go on and do more with it.”
AcknowledgementsNational Science Foundation (Chemistry, CCI, MRI, I-Corps)National Radio Astronomy ObservatoryVA NC Alliance LSAMPUniversity of Virginia
David Pratt, Steve Shipman, Bob Field, David Perry, Tom GallagherMike McCarthy, Tony Remijan, Phil Jewel, Susanna Widicus-WeaverRick Suenram, Frank Lovas, David PlusquellicZbyszek Kisiel, George Shields, Berhane Temelso, Jeremy Richardson, Stuart Althorpe, David Wales, Alberto Lesarri, Sean Peebles, Rebecca Peebles, Gamil Guirgis, Jim Durig, Isabelle Kleiner, Bob McKellar, Kevin Lehmann
Pate Broadband Rotational Spectroscopy GroupGordon Brown, Kevin Douglass, Brian Dian, Steve ShipmanMatt Muckle, Justin Neill, Dan Zaleski, Brent Harris, Amanda Steber, Nathan Seifert,Cristobal Perez, Simon Lobsiger, Luca Evangelisti
Broadband rotational spectroscopy has been used to explore interesting questions in the structure of water clusters including isomerism, quantum effects, tunneling, and hydrogen bond cooperativity.
Broadband Rotational Spectroscopy
The chirped-pulse Fourier transform (CP-FT) technique offers significant advantages for broadband rotational spectroscopy..
Chirped-pulse Fourier transform spectroscopy techniques have been extended to mm-wave spectroscopy for high-speed spectrum acquisition.
Dyke, T. R., Muenter, J. S., J. Chem. Phys. 1974 2929.
Liu, K.; Brown, et al. Nature 1996, 381, 501.N. Pugliano and R. J. Saykally, Science 1992 257 1937.Liu, K.; Brown, M.G.; Cruzan, J.D.; Saykally, R.J. Science 1996, 271, 62.K. Liu, J. D. Cruzan, R. J. Saykally, Science 1996 271 929.Cruzan, J.D..et al Science 1996, 271 59.Richardson, J. O. et al., J. Phys. Chem. A, Article ASAP (2013).
Microwave Spectroscopy
THz Spectroscopy
Low Frequency CP-FTMW Spectroscopy: 2-8 GHzNormal Water Spectrum:3 Hexamers2 Heptamers5 Nonamers4 Decamers7 Undecamers2 Tridecamer1 Pentadecamer
• 700 transitions (140 MHz of bandwidth)• 1700 transitions at 3:1 signal-to-noise ratio or higher unassigned
Trot < 10K
Isotope Spiking: ~15% H218O
Water Clusters Identified in a Single Measurement (H2O)6 (H2O)7
(H2O)9
(H2O)10
(H2O)13 (H2O)15
(H2O)11
Isomers of the Water Hexamer: (H2O)6
rms O…O bond length differences: ~0.01 Angstrom
All three isomers observed neon carrier
Only the CAGE is observed with argon
Prism Cage Book
The (D2O)6 prism has a relatively lower energy by ~0.1 kcal/mol
Valon 5008 Dual Synthesizer$395www.valontechnology.com
Mini CircuitsSMA Adapter$8.95
Broadband rotational spectroscopy has been used to explore interesting questions in the structure of water clusters including isomerism, quantum effects, tunneling, and hydrogen bond cooperativity.
Broadband Rotational Spectroscopy
The chirped-pulse Fourier transform (CP-FT) technique offers significant advantages for broadband rotational spectroscopy..
Chirped-pulse Fourier transform spectroscopy techniques have been extended to mm-wave spectroscopy for high-speed spectrum acquisition.