eprintid: 33693 rev_number: 13 userid: 7404 dir: disk0/00/03/36/93 datestamp: 2018-06-28 19:28:57 lastmod: 2018-06-28 19:28:57 status_changed: 2018-06-28 19:28:57 type: thesis_degree metadata_visibility: show contact_email: zhr3@pitt.edu eprint_status: archive creators_name: Ren, Zhe creators_email: ZHR3@pitt.edu creators_id: ZHR3 creators_orcid: 0000-0001-7793-1581 title: Ultrafast structure and dynamics of ionic liquids revealed by two-dimensional infrared spectroscopy ispublished: unpub divisions: sch_as_chemistry full_text_status: public keywords: ionic liquids, thiocyanate, 2D-IR, solvation dynamics. abstract: Two-dimensional infrared spectroscopy (2D-IR) is a non-linear spectroscopy that is capable of resolving molecular dynamics with picosecond time resolution and molecular-level spatial resolution. 2D-IR has been successfully implemented in a myriad of solution systems to study the local solute and solvent dynamics. Ionic liquids are a unique type of liquid with each formula unit a pair of cation and anion. The structure grants it unique properties that are suitable for many potential applications, and the chemical structure can be modified to be “task-specific”. In this thesis, I describe our implementation of 2D-IR to understand different aspects of the solvation dynamics of ionic liquids, including solvent dynamics, ultrafast structures and dynamics of small solutes, and the dynamics of ionic liquids under confinement. A direct correlation between the microscopic solvent dynamics and the macroscopic viscosity has been observed, indicating the molecular origin of viscosity in ionic liquids is possibly the ion-cage lifetime. Some small inorganic salts form ion-pairs in the ionic liquids, and have a Gibbs free energy of ~8 kJ/mol. Some uncharged small molecules can cluster in ionic liquids, like water clusters with thiocyanate anion. The detailed structural and reorientation dynamics of ionic liquid-surfactant complexes imply a random cluster picture, rather than previously-believed reverse micelle picture; the shape of the dynamic correlation function also indicates a non-isotropic local orientation distribution that could originate from the ion-exchange between anionic surfactants and ionic liquids. date: 2018-06-28 date_type: published pages: 177 institution: University of Pittsburgh refereed: TRUE etdcommittee_type: committee_chair etdcommittee_type: committee_member etdcommittee_type: committee_member etdcommittee_type: committee_member etdcommittee_name: Garrett-Roe, S etdcommittee_name: Waldeck, DH etdcommittee_name: Coalson, R etdcommittee_name: Kim, Hyung etdcommittee_email: sgr@pitt.edu etdcommittee_email: dave@pitt.edu etdcommittee_email: coalson@pitt.edu etdcommittee_email: hjkim@cmu.edu etdcommittee_id: SGR etdcommittee_id: DAVE etdcommittee_id: COALSON etd_defense_date: 2017-12-21 etd_approval_date: 2018-06-28 etd_submission_date: 2018-01-10 etd_release_date: 2018-06-28 etd_access_restriction: immediate etd_patent_pending: FALSE thesis_type: dissertation degree: PhD citation: Ren, Zhe (2018) Ultrafast structure and dynamics of ionic liquids revealed by two-dimensional infrared spectroscopy. Doctoral Dissertation, University of Pittsburgh. (Unpublished) document_url: http://d-scholarship-dev.library.pitt.edu/33693/7/zhe_ren_etd.pdf