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Beyond the Bend: Exploring the Conformational Landscape of Decyl, Undecyl, and Dodecylbenzene
Daniel M. Hewett, Simply John T. Lawler, and Timothy S. Zwier Department of Chemistry, Purdue University Funding: DOE Basic Energy Sciences Combustion Program Funding
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Motivations ? ? Nils O. B. Lüttschwager, Tobias N. Wassermann, Ricardo A. Mata, Martin A. Suhm The Last Globally Stable Extended Alkane Angew. Chem. Int. Ed. 52 (2013) I would remove the reference to soot formation. It’s too subtle a connection to make. Identifying the First Folded Alkylbenzene via Ultraviolet, Infrared, and Raman Spectroscopy of Pentylbenzene through Decylbenzene Daniel M. Hewett, Sebastian Bocklitz, Daniel P. Tabor, Edwin L. Sibert III,* Martin A. Suhm, and Timothy S. Zwier
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Fluorescence Excitation and Dispersed Fluorescence Chamber
7/20/2018 Fluorescence Excitation and Dispersed Fluorescence Chamber Detect total fluorescence UV laser tuned Conformer A (S0, ZPL) A*(S1)
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Ground State Methods LIF S0-FDIRS Tune UV Laser
Collect Total Fluorescence Collect Total Fluorescence Fix UV Laser Add in a couple of words: on LIF: ‘Tune UV laser’ and ‘Collect total fluorescence’ On S0 FDIRS: Tune IR and ‘Fix UV on conformer origin’ Tune IR Laser LIF S0-FDIRS
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Octylbenzene: g1g3g4 g=gauche defect in the chain
Eureka! Look at all that structure! no more lumps, theory predicts three major bands in middle region, gets the 2950 band from the double gauche, additional activity in low region g=gauche defect in the chain
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Folded vs. Extended Octylbenzene Folded All Trans
Eureka! Look at all that structure! no more lumps, theory predicts three major bands in middle region, gets the 2950 band from the double gauche, additional activity in low region Octylbenzene Folded All Trans
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UV Spectra: S0-S1 origin region
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Energy Level Diagrams all trans all trans Octylbenzene Decylbenzene
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UV Spectra: S0-S1 origin region
Add relative scale from the all trans
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Decylbenzene IR Spectra
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Decylbenzene IR Spectra
g1g2g4g5 = 0.10 kJ/mol g1g’4g’5 = 1.31 kJ/mol
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Decylbenzene IR Spectra
g1g2g4g5 = 0.10 kJ/mol g1g’4g’5 = 1.31 kJ/mol
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Undecylbenzene IR Spectra
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Dodecylbenzene IR Spectra
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Future Work Diaryls Where’s the stack?
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Conclusions Observed rapid increase in folded conformer population as chain length increases Alkyl CH stretch region becoming very difficult to use as a spectroscopic tool as chain length increases
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Acknowledgements Dr. Tim Zwier Simply John T. Lawler The Zwier group
DOE
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