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Title: SISGR: Physical Chemistry of Reaction Dynamics in Ionic Liquids

Abstract

Room temperature ionic liquids (RTILs) are liquids made up of atomic and molecular ions. This is in contrast with more common liquids, such as water, that are made up of neutral molecules. The additional charges on the atoms and molecules can alter the properties of these liquids, for example they tend to have a very high vapor pressure and the ability to shield charge in electronic devices. For these and other reasons RTILs have recently been deployed in a number of applications that involve production of free electrons in the liquid, such as batteries, capacitors, nuclear power plants, and solar cells. Electrons tend to be very reactive, and understanding their behaviour in these liquids is important for the future design of ionic liquids to be employed in these environments. This study investigated the behavior of electrons generated in RTILs by pulses of ultraviolet light, including how long they survive, and how reactive they are with the both the surrounding liquid and impurities in the liquid. The ionic liquid studied was one of the most commonly used, called N-alkyl-N-methyl-pyrrolidinium bistriflimide. What the study revealed was that the majority of the electrons initially created, about 96%, had a very short lifetime ofmore » less than one picosecond (10-12 second) due to a process called geminate recombination. The study also demonstrated that the electrons are very reactive at the moment they are detached from the molecules in the liquid by light, but that they relax very quickly and lose almost all of their reactivity in much less than one picosecond. The short lifetime and rapid loss of reactivity both serve as important mechanisms that protect the liquid from radiolytic damage.« less

Authors:
 [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States)
Publication Date:
Research Org.:
Univ. of Minnesota, Minneapolis, MN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1405286
Report Number(s):
DE-SC0008665
DOE Contract Number:
SC0008665
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 25 ENERGY STORAGE

Citation Formats

Blank, David. SISGR: Physical Chemistry of Reaction Dynamics in Ionic Liquids. United States: N. p., 2017. Web. doi:10.2172/1405286.
Blank, David. SISGR: Physical Chemistry of Reaction Dynamics in Ionic Liquids. United States. doi:10.2172/1405286.
Blank, David. 2017. "SISGR: Physical Chemistry of Reaction Dynamics in Ionic Liquids". United States. doi:10.2172/1405286. https://www.osti.gov/servlets/purl/1405286.
@article{osti_1405286,
title = {SISGR: Physical Chemistry of Reaction Dynamics in Ionic Liquids},
author = {Blank, David},
abstractNote = {Room temperature ionic liquids (RTILs) are liquids made up of atomic and molecular ions. This is in contrast with more common liquids, such as water, that are made up of neutral molecules. The additional charges on the atoms and molecules can alter the properties of these liquids, for example they tend to have a very high vapor pressure and the ability to shield charge in electronic devices. For these and other reasons RTILs have recently been deployed in a number of applications that involve production of free electrons in the liquid, such as batteries, capacitors, nuclear power plants, and solar cells. Electrons tend to be very reactive, and understanding their behaviour in these liquids is important for the future design of ionic liquids to be employed in these environments. This study investigated the behavior of electrons generated in RTILs by pulses of ultraviolet light, including how long they survive, and how reactive they are with the both the surrounding liquid and impurities in the liquid. The ionic liquid studied was one of the most commonly used, called N-alkyl-N-methyl-pyrrolidinium bistriflimide. What the study revealed was that the majority of the electrons initially created, about 96%, had a very short lifetime of less than one picosecond (10-12 second) due to a process called geminate recombination. The study also demonstrated that the electrons are very reactive at the moment they are detached from the molecules in the liquid by light, but that they relax very quickly and lose almost all of their reactivity in much less than one picosecond. The short lifetime and rapid loss of reactivity both serve as important mechanisms that protect the liquid from radiolytic damage.},
doi = {10.2172/1405286},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Technical Report:

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  • The Margulis group BES funded research at the University of Iowa is part of a broader collaborative effort that includes the groups of Blank (U. Minnesota), Castner (Rutgers U.), Maroncelli (Penn. State U.) and Wishart (BNL). The goal of this group of PIs is to better understand from an experimental and a theoretical perspective different aspects of photo-initiated electron transfer processes in a set of different room-temperature ionic-liquid systems. The Margulis contribution is theoretical and computational. Details are presented in the attached documentation.
  • Work completed over the past year mainly involves finishing studies related to solvation dynamics in ionic liquids, amplifying and extending our initial PFG-NMR work on solute diffusion, and learning how to probe rotational dynamics in ionic liquids.
  • Obtaining fundamental understanding and developing predictive modeling capabilities of electrochemical interfaces can significantly shorten the development cycles of electrical double layer capacitors (EDLCs). A notable improvement in EDLC performance has been achieved due to recent advances in understanding charge storage mechanisms, development of advanced nanostructured electrodes and electrochemically stable electrolytes. The development of new generation of EDLCs is intimately linked to that of nanostructured carbon materials which have large surface area, good adsorption/desorption properties, good electrical conductivity and are relatively inexpensive. To address these scientific challenges the efforts of an interdisciplinary team of modelers and experimentalists were combined to enhancemore » our understanding of molecular level mechanisms controlling the performance of EDLCs comprised of room temperature ionic liquid (RTIL) electrolytes and nanostructured carbon-based electrodes and to utilize these knowledge in the design of a new generation of materials and devices for this energy storage application. Specifically our team efforts included: atomistic molecular dynamics simulations, materials science and electrode/device assembly, and synthesis and characterization of RTIL electrolytes.« less
  • Our goal is to understand the structure and dynamics of water, in its different phases, at the interfaces between these phases, and in confined and heterogeneous environments. To this end, linear and nonlinear vibrational spectroscopy is playing a very important role. We have developed techniques for calculating spectroscopic observables, and then used our results to analyze and interpret experiment.
  • The long-range goal of our DOE-sponsored research is to obtain a fundamental understanding of solvation effects on photo-induced charge transfer and related processes. Much of the focus during the past funding period has been on studies of ionic liquids and on characterizing various reactions with which to probe the nature of this interesting new solvent medium.