Publications by authors named "Clinton A Johnson"
The dynamics of excess protons in the protic ionic liquid (PIL) ethylammonium formate (EAF) have been investigated from femtoseconds to microseconds using visible pump mid-infrared probe spectroscopy. The pH jump following the visible photoexcitation of a photoacid (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt, HPTS) results in proton transfer to the formate of the EAF. The proton transfer predominantly (∼70%) occurs over picoseconds through a preformed hydrogen-bonded tight complex between HPTS and EAF.
View Article and Find Full Text PDFUsing ultrafast two-dimensional infrared spectroscopy (2D-IR), a vibrational probe (thiocyanate, SCN) was used to investigate the hydrogen bonding network of the protic ionic liquid ethyl-ammonium nitrate (EAN) in comparison to HO. The 2D-IR experiments were performed in both parallel (⟨ZZZZ⟩) and perpendicular (⟨ZZXX⟩) polarizations at room temperature. In EAN, the non-Gaussian lineshape in the FTIR spectrum of SCN suggests two sub-ensembles.
View Article and Find Full Text PDFArticle Synopsis
- The study investigates the dynamics of ionic liquid (IL)-surfactant complexes using two-dimensional infrared spectroscopy (2D-IR) to deepen understanding of their behavior.
- Various surfactants and solvents, along with different IL-to-surfactant ratios have significant impacts on the structure and motion of ILs within the complexes, ranging from stable micro-environments to fast-evolving ones.
- The findings suggest that these systems do not form a traditional ionic liquid-reverse micelle structure but may instead consist of small colloidal dispersions or pairs of IL and surfactant, with potential implications for ion-exchange mechanisms.
Article Synopsis
- The CO2ν3 asymmetric stretching mode is used for ultrafast 2D-IR spectroscopy to study ionic liquids' local structure and dynamics, which are important for carbon capture.
- The frequency of the ν3 mode changes based on the specific ionic liquid's solvation environment, significantly affecting local structural relaxation times.
- Density functional theory indicates charge transfer between CO2 and the ionic liquid components, causing geometrical changes in CO2 and influencing its vibrational frequency, with structural relaxation times varying considerably across different ionic liquids.