Observation of surface structure of 1-butyl-3-methylimidazolium hexafluorophosphate using high-resolution Rutherford backscattering spectroscopy

Ohno, Atsushi; Hashimoto, H.; Nakajima, K.; Suzuki, Motofumi; Kimura, Kenji

doi:10.1063/1.3141385

Cited by 30 publications

(30 citation statements)

References 36 publications

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“…In our previous papers, we have observed surface structures of various ILs. 27,36,37 We found that all observed ILs are shared almost equally between cations and anions although preferential orientations of either cation or anion were observed in some cases. Similar structures were also observed using various other techniques.…”

Section: -3mentioning

confidence: 74%

Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy

Nakajima

Ohno

Hashimoto

et al. 2010

The Journal of Chemical Physics

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The surface structures of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C(n)MIM][TFSI], n=2,4,6) are studied by high-resolution Rutherford backscattering spectroscopy. The average composition of the surface molecular layer is very close to the stoichiometric composition, showing that neither ion is enriched in the surface layer. A detailed analysis indicates that both cations and anions have preferential molecular orientations at the surface. The alkyl chains of the [C(n)MIM] cations protrude to the vacuum and the CF(3) groups of the [TFSI] anions are also pointing toward the vacuum. While the orientation of the [TFSI] anion becomes weaker with increasing alkyl-chain length, the protrusion of the alkyl chain occurs irrespective of the chain length. It was also found that the N(SO(2))(2) moiety is located nearly at the same depth as the imidazolium ring, suggesting that one of oxygen atoms in [TFSI] is bonded to the hydrogen of the C(2) carbon atom of the imidazolium ring.

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Section: -3mentioning

confidence: 74%

Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy

Nakajima

Ohno

Hashimoto

et al. 2010

The Journal of Chemical Physics

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“…Rutherford backscattering spectra for the ͓bmim͔ + / ͓PF 6 ͔ − -vacuum interface also show the cation butyl group protruding from the bulk liquid into vacuum. 113 SFG measurements at the air-IL interface 118 showed that for longer alkyl chains, the number of gauche defects on this cation substituent decreased relative to short chains. This is in contrast to the substantial fraction of gauche defects on bulk alkylimidazolium cations in ILs deduced from Raman spectroscopy.…”

Section: Il Interfacesmentioning

confidence: 99%

“…A wide variety of experimental, theoretical, and simulation methods have been applied to the study of ILs at interfaces. [107][108][109][110][111][112][113][114][115][116][117][118][119][120][121][122] Santos and Baldelli 112 have used interfacial sumfrequency generation ͑SFG͒ to show that at IL interfaces with gases or vacuum, alkyl chains on either the cations or the anions extend from the surface into the gas or vacuum. Rutherford backscattering spectra for the ͓bmim͔ + / ͓PF 6 ͔ − -vacuum interface also show the cation butyl group protruding from the bulk liquid into vacuum.…”

Section: Il Interfacesmentioning

confidence: 99%

Spotlight on ionic liquids

Castner

Wishart

2010

The Journal of Chemical Physics

380

328

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Ionic liquids are an emerging class of materials with a diverse and extraordinary set of properties. Understanding the origins of these properties and how they can be controlled by design to serve valuable practical applications presents a wide array of challenges and opportunities to the chemical physics and physical chemistry community. We highlight here some of the significant progress already made and future research directions in this exciting area.

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“…The direct recoil spectrometry measurements indicated a perpendicular distribution of imidazolium ring planes and a parallel orientation of butyl chains in [BMIM] cations in IL-gas interfacial region [94]. However, experimental characterizations based on sum frequency generation (SFG), high-resolution Rutherford backscattering spectroscopy and X-ray reflectivity observations [95][96][97][98] suggested that imidazolium rings prefer to take flat orientations along IL-gas interface, whilst butyl chains are loosely packed together and protruded from liquid phase into gas phase with a certain tilt. Additionally, in IL-solid interfacial region, nuclear magnetic resonance experiments showed that interfacial ionic structures of supported [BMIM][PF 6 ] IL depend strongly on solid surface types and the thickness of the confined IL film [93].…”

Section: Tetraalkylphosphonium-orthoborate Ionic Liquid-water Mixturesmentioning

confidence: 99%

4. Multigranular modeling of ionic liquids

Wang¹,

Sarman²,

Laaksonen³

et al. 2019

Ionic Liquids

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Ionic liquids (ILs) are a special category of molten salts with melting points near ambient temperatures (or by convention below 100°C). Owing to their numerous valuable physicochemical properties as bulk liquids, solvents, at surfaces and in confined environments, ILs have attracted increasing attention in both academic and industrial communities in a variety of application areas involving physics, chemistry, material science and engineering. Due to their nearly limitless number of combinations of cation-anion pairs and mixtures with cosolvents, a molecular level understanding of their hierarchical structures and dynamics, requiring strategies to connect several length and time scales, is of crucial significance for rational design of ILs with desired properties, and thereafter refining their functional performance in applications. As an invaluable compliment to experiments from synthesis to characterization, computational modeling and simulations have significantly increased our understanding on how physicochemical and structural properties of ILs can be controlled by their underlying chemical and molecular structures. In this chapter, we will give examples from our own modeling work based on selected IL systems, with focus on imidazolium-based and tetraalkylphosphonium-orthoborate ILs, studied at several spatio-temporal scales in different environments and with particular attention to applications of high technological interest. We start by describing studies performed using ab initio methods on force field development for tetraalkylphosphonium-orthoborate ILs, and computational studies on thermal decomposition of these ILs. The delicate interplay between hydrogen bonding and π-type interactions in an imidazolium-orthoborate IL was studied by performing ab initio molecular dynamics simulations. On the atomistic level, atomistic simulations were performed with constructed force field parameters to study intrinsic molecular interactions between residual water molecules and tetraalkylphosphoniumorthoborate ionic species. For a typical trihexyltetradecylphosphonium bis(oxalato) borate IL at varied concentrations, microstructures and dynamics were systematically analyzed as water concentration increases. The liquid viscosities of typical trihexyltetradecylphosphonium-based ILs were estimated through equilibrium atomistic simulations using Green-Kubo relation with charge scaling factors on ionic species.Additionally, atomistic simulations were combined with X-ray scattering experiments to investigate phase behavior and ionic structures in IL mixtures with varied concentrations. Peculiar features of X-ray scattering spectra of IL mixtures with organic solvent are also discussed with an example dealing with ethyl ammonium nitrate and acetonitrile mixtures. On the mesoscopic level, a united-atom model for trihexyltetradecylphosphonium cation and coarse-grained models for butylmethy-limidazolium hexafluorophosphate were proposed, and effective interactions between coarse-grained beads were validated against experimental...

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Observation of surface structure of 1-butyl-3-methylimidazolium hexafluorophosphate using high-resolution Rutherford backscattering spectroscopy

Cited by 30 publications

References 36 publications

Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy

Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy

Spotlight on ionic liquids

4. Multigranular modeling of ionic liquids

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