?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F33300%2F&rft.title=Ultrafast+Dynamics+of+Carbon+Dioxide+in+Imidazolium+Ionic+Liquids&rft.creator=Brinzer%2C+Thomas&rft.description=The+ultrafast+vibrational+dynamics+of+carbon+dioxide+(CO2)+were+studied+in+a+series+of+physisorbing+ionic+liquids+using+two-dimensional+infrared+(2D-IR)+spectroscopy.+The+microscopic+dynamics+reported+by+CO2+were+found+to+depend+strongly+on+the+choice+of+anion.+The+timescales+of+spectral+diffusion+are+attributed+to+the+breakup+of+a+local+solvent+shell+(ion+cage)+around+CO2%2C+and+to+correlate+with+the+bulk+viscosity+in+1-alkyl-3-methylimidazolium+ionic+liquids.+This+correlation+breaks+for+novel+ionic+liquid+mixture+with+short+alkyl+sidechains+and+non-imidazolium+head+groups%3B+however%2C+the+timescales+of+spectral+diffusion+are+consistent+with+trends+in+ion+transport+(conductivity).%0D%0A%0D%0AA+semi-empirical+spectroscopic+map%2C+developed+from+ab+initio+calculations%2C+allowed+comparison+of+experimental+observables+with+molecular+dynamics+simulations.+The+observed+and+calculated+frequency+and+reorientational+dynamics+of+CO2+were+compared%2C+finding+good+correspondence.+Both+frequency+and+reorientational+dynamics+show+multi-exponential+behavior%2C+indicating+complex+dynamics.+Decomposition+of+the+calculated+frequency+fluctuation+correlation+function+(FFCF)+into+contributions+from+structural+components+of+the+ions+confirms+that+the+longest+timescale+is+dominated+by+interactions+of+the+anion+and+CO2%3B+however%2C+there+are+substantial+contributions+from+inertial+motions+involving+the+cation's+charged+head+group.%0D%0A%0D%0ATemperature-dependent+2D-IR+of+thiocyanate+(%5BSCN%5D-)+and+CO2+in+1-alkyl-3-imidazolium+bistriflimide+(%5BIm_%7Bn%2C1%7D%5D%5BTf2N%5D%2C+n+%3D+2%2C4%2C6)+ionic+liquids+interrogated+the+energetic+barriers+to+motions+around+the+probe+molecules+and+the+effect+of+increasing+ionic+liquid+heterogeneity+on+the+observed+dynamics.+Both+%5BSCN%5D-+and+CO2+show+a+strong+correlation+of+microscopic+dynamics+with+viscosity+in+each+ionic+liquid+studied%3B+however%2C+the+spectral+diffusion+of+%5BSCN%5D-+in+%5BIm_%7B2%2C1%5D%5BTf2N%5D+is+offset+from+those+of+%5BSCN%5D-+in+the+longer+chain+ionic+liquids%2C+potentially+because+of+rotational+motions.+Additionally%2C+both+%5BSCN%5D-+and+CO2+show+activated+behavior+in+their+spectral+diffusion%2C+with+the+activation+barrier+being+dominated+by+the+slowest+resolved+relaxation+processes.+The+calculated+barriers+for+both+CO2+and+%5BSCN%5D-+correspond+broadly+to+those+for+ion+self-diffusion+from+MD+and+NMR+studies.+%5BSCN%5D-+shows+a+decrease+in+E_a+for+n%3D6%2C+possibly+because+of+increasing+nanoscopic+polar-apolar+segregation.+The+calculated+barriers+for+CO2+do+not+show+this+dependence+on+alkyl+chain+length%2C+consistent+with+molecular+modeling+of+the+CO2+frequency.&rft.date=2018-06-15&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F33300%2F7%2Ftbrinzer_etd.pdf&rft.identifier=++Brinzer%2C+Thomas++(2018)+Ultrafast+Dynamics+of+Carbon+Dioxide+in+Imidazolium+Ionic+Liquids.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++