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Spectroscopy With Polarized Light: Polarized Matrix Infrared Spectra of Cyclopentadieneone THOMAS K. ORMOND, ADAM M. SCHEER, G. BARNEY ELLISON, Department.

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Presentation on theme: "Spectroscopy With Polarized Light: Polarized Matrix Infrared Spectra of Cyclopentadieneone THOMAS K. ORMOND, ADAM M. SCHEER, G. BARNEY ELLISON, Department."— Presentation transcript:

1 Spectroscopy With Polarized Light: Polarized Matrix Infrared Spectra of Cyclopentadieneone THOMAS K. ORMOND, ADAM M. SCHEER, G. BARNEY ELLISON, Department of Chemistry and Biochemistry, University of Colorado, Boulder; MARK R. NIMLOS, Center for Renewable Chemical, Technologies & Materials, NREL, Golden, CO; JOHN W. DAILY, Department of Mechanical Engineering, University of Colorado, Boulder; and JOHN F. STANTON, Institute for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin OSU MOLECULAR SPECTROSCOPY SYMPOSIUM JUNE, 2012 Thomas K. Ormond G. Barney Ellison Group Department of Chemistry and Biochemistry University of Colorado, Boulder

2 Intermediate in thermal decomposition pathways of lignin model monomers leading to formation of acetylenes and substituted acetylenes – known precursors to PAHs and soot Partial anti aromatic character and rapid dimerization - cannot be isolated Cyclopentadieneone (C 5 H 4 =O) Depuy & Lyons, J. Am. Chem. Soc. 1960, 82,

3 Scheer, Mukarakate, Robichaud, Nimlos, & Ellison, Thermal Decomposition Mechanisms of the Methoxyphenols, J. Phys. Chem. A 2011, 115,

4 Cyclopentadieneone (C 5 H 4 =O) Need a clean source of C 5 H 4 =O and deuterated species: C 5 D 4 =O and C 5 H 2 D 2 =O - Synthesis of o-phenylene sulfite DeJongh, D.C.; Van Fossen, R.Y.; Bourgeois, C.F. Tetrahedron Lett., 1967, 271.

5 1 mm SiC 300–1700 K  (tubular reactor)  50 µsec Supersonic Jet of Radicals/He into Torr IE( C 5 H 4 =O )  9.49 eV nm VUV Laser ( eV)   VUV + C 54 =O  C 5 H 4 =O + + e – phenylene sulfite entrained in He/Ar carrier gas. pulsed valve 1 msec 10 Hz Molecular diagnostics: C 5 H 4 =O + VUV-TOF-PIMS detection and matrix isolation FTIR 64 cm Wiley-McLaren TOF spectrometer m/  m  2100 Temperature monitor Optical Pyrometer Supersonic Jet of Radicals/Ar into Torr onto CsI 10 K C 5 H 4 =O molecular beam diagnostics

6 C 5 H 4 =O molecular beam diagnostics: nm ( eV) photoionization mass spectrometry

7 C 5 D 4 =O molecular beam diagnostics: nm ( eV) photoionization mass spectrometry – fully deuterated isotopomer

8 C 5 H 4 =O and C 5 D 4 =O matrix infrared absorption spectroscopy

9 C 5 H 4 =O molecular beam diagnostics: matrix infrared absorption spectroscopy

10 C 5 H 4 =O molecular beam diagnostics: matrix infrared absorption spectroscopy

11 z x y z x y y-polarized UV radiation photo orients sample via electronic transition y-polarized IR radiation excites b 2 vibrational transitions [Abs(Y)], z- polarized IR excites a 1 vibrations [Abs(Z)] Linear dichroism IR spectroscopy: Carbonyl dissociative transition – formaldehyde test case In this way, we can selectively excite vibrations of a particular symmetry

12 Linear dichroism IR spectroscopy: Carbonyl dissociative transition – formaldehyde test case

13 Linear dichroism IR spectroscopy: Cyclopentadieneone

14 Linear dichroism IR spectroscopy: d4-Cyclopentadieneone

15 Linear dichroism IR spectroscopy: d4-Cyclopentadieneone

16 This work is funded by the NSF and DOE Ellison (CU Boulder) and Nimlos (NREL) group members Don David and Ken Smith (CIRES machine shop) Chuck Depuy (CU Boulder) Hans-Heinrich Carstensen (Colorado School of Mines) Thanks to:


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