PhD Defense: Qin Ong

On June 14th, DIFFER PhD researcher Qin Ong will defend her thesis, titled 'Vibrational excitement: mode-selective conversion of CO₂' at 13:30h

Research summary
In this work, the conversion of CO₂ to CO by vibrational energy excitation exchanges via collisions is tested in mid-infrared laser experiments. CO₂ gas is vibrationally excited to the first (few) vibrational levels of the asymmetric stretch mode using photons that are 19 times lower than the required energy to break CO₂. The energy exchanges induced by collisions lead to molecular dissociation forming CO and O₂. The CO molecules accumulate in the stagnant gas cell during 5 to 20-minute laser excitation and are detected by Fourier Transform InfraRed (FTIR) spectroscopy.

The overall conclusion shows that CO₂ vibrational energy transfer via collisions remains sufficiently in the vibrational mode of interest for CO₂ dissociation and chemistry with a co-reactant. This allows vibrationally driven chemistry occurring at a much lower temperature than conventional thermal driven chemistry. For CO₂, temperatures of at least 2000 K are required to obtain significant dissociation. Here, dissociation is achieved at room temperature (300 K). The results demonstrate that collisions, typically avoided in mode-selective chemistry, facilitate vibrational ladder climbing and low-temperature dissociation of CO₂, which is remarkable considering the various energy dissipation channels for CO₂. This work lays the groundwork for future research into mode-selective chemistry driven by collisions and may open new windows on CO₂ utilization routes towards the synthesis of fuels and chemicals.

Thesis
The thesis will be uploaded here after embargo is lifted (15-6)

Committee members
1st promotor: prof.dr.ir. G.J. van Rooij
2nd promotor: prof.dr.ir. M.C.M. van de Sanden
Members: prof.dr. G. Mul (Universiteit Twente), prof.dr. U.M. Ebert, prof.dr. A.M. Rijs (Vrije Universiteit Amsterdam), prof.dr. V.L. Guerra (Universidade de Lisboa)
Advisor: dr. G. Berden (Radboud Universiteit)

Link to the public event can be found here