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Nonthermal Chemistry Induced by Visible Light
- H. Floyd Davis
Department of Chemistry and Chemical Biology Cornell University
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Reactions of Triplet Diacetylene HCCCCH
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Nonthermal Chemistry Induced by Visible Light H. Floyd Davis - - PowerPoint PPT Presentation
Nonthermal Chemistry Induced by Visible Light H. Floyd Davis - - PowerPoint PPT Presentation
Nonthermal Chemistry Induced by Visible Light H. Floyd Davis Department of Chemistry and Chemical Biology Cornell University 1 Reactions of Triplet Diacetylene HCCCCH 2 Reactions of Triplet Diacetylene HCCCCH Zwier Group, Purdue 3
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Reactions of Triplet Diacetylene HCCCCH Zwier Group, Purdue
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Zwier, Science 258, 1630 (1992)
Photoinduced Reactivity of Diacetylene, C4H2
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Spectrum of Solar Radiation on Titan
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Vibrational Levels of Molecules
Infrared Absorption e.g., C-H stretch V = 0 → 1
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Vibrational Levels of Molecules
First Overtone excitation (v = 0 →2)
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Vibrational Levels of Molecules
Fourth Overtone excitation (v = 0 →5)
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Why is the ocean blue? Due to OH Overtone Absorption of red light
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Calculated Singlet C4H4 Energetics Mebel, J. Chem. Phys. 125, 133113 (2006) Addition barrier is 140 kJ/mol. Corresponds to photon at 856 nm
Calculated singlet C4H4 energetics (kJ/mol)
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Spectrum of Solar Radiation on Titan
C2H2 v = 0 →5 band at 640 nm
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Acetylene 5 vCH Photoacoustic Spectrum
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Acetylene 4 vCH Overtone Spectrum (787 nm): Room Temp vs. Molecular Beam. Low T Room T
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Pulsed Valve/Flow Reactor Laser
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VUV Photoionization TOF Apparatus
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Absorption Spectra of Polyenes Christensen, J. Phys. Chem. A 117, 1449 (2013)
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Electronic Excitation Energies of Polyenes Decrease with number of monomer units, N “1D particle in a box”
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What about HCN Polymerization?
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Acknowledgements:
Jonathan Lunine David Shalloway David Usher
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Polyene Photochemistry (Kohler)
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Nonreactive Scattering of C2H2 (v) with other molecules
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Polymerization of Acetylene?
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UV Excitation Produces Triplet Acetylene
- J. Chem. Phys 106, 5292 (1997)
No triplets formed above 5.86 eV: Due to onset of photodissociation
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Zwier, Science 258, 1630 (1992)
Laser off Laser on Difference
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