Northwestern Events Calendar

Mar
14
2017

Ivan Antonov: Spectroscopy and reactions of small molecules: from ThF to THF

When: Tuesday, March 14, 2017
2:00 PM - 3:00 PM CT

Where: Technological Institute, F160, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Post Docs/Docs - Graduate Students

Contact: Tina Hoff   (847) 491-3645

Group: AMO: The Atomic, Molecular, and Optical Physics Seminar

Category: Lectures & Meetings

Description:

Title: Spectroscopy and reactions of small molecules: from ThF to THF

Speaker: Ivan Antonov, Sandia National Laboratories

Abstract: Molecular structure reveals itself in various molecular properties including light-matter interactions and reactivity. Presented in this talk are studies that advanced understanding of molecular structure in connection with electronic spectroscopy and reaction dynamics of two systems: thorium fluoride cation (ThF+) and tetrahydrofuran (THF) oxidation.
The 3Δ1 electronic state of ThF+ was recently proposed as a prospective candidate for electron electric dipole moment determination. Low-lying electronic states of ThF+ were studied with laser induced fluorescence and Pulsed Field Ionization – Zero Electron Kinetic Energy spectroscopy. Accurate ionization energy of ThF was measured and it was found that the bond shortens and weakens upon ionization. Additionally, W=0 (1Σ+) and W=1, 2, 3 (3Δ) states were located and characterized. It was determined that the molecular structure of ThF+ and the strong spin-orbit interaction of Th resulted in a large splitting of 3Δ term which brought the energy of 3Δ1 state below the 1Σ+.
THF is prototypical cyclic ether and a structural element of proposed second-generation biofuels. Low temperature oxidation of THF was studied with a combination of experimental and theoretical techniques. We found that pressure- and temperature-dependent competition between pathways on the THF-yl + O2 and hydroperoxy-THF-yl + O2 potential energy surfaces is of central importance in modeling the autoignition properties of THF oxidation. The heterocycle ring structure of THF affects the shape of reaction potential energy surfaces and adds complexity to the reaction mechanism due to formation of EZ-isomers. These E/Z isomers were found to have distinct reactivity, thus impacting the low temperature oxidation of THF, and potentially larger cyclic ether biofuels. A simplified mechanism of THF oxidation below 700K was developed.

Host: Brian Odom

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