Dynamic Heterogeneity in Room-Temperature Ionic Liquids

Jeong, Daun; Kim, Daekeon; Choi, Myoungsub; Kim, Hyung J.; Jung, YounJoon

doi:10.5772/15211

Cited by 4 publications

(5 citation statements)

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“…This would imply that the probes do not switch between different regions while passing through the focal volume, a process that takes milliseconds. In contrast to this bimodal picture of local heterogeneity, neutron scattering ,, and simulations − have shown that ILs are glassy. In a glassy environment, the diffusion of probes is non-Gaussian, the mean square displacement (MSD) is best expressed as a power law, and the intermediate scattering function exhibits stretched exponential behavior. ,,,, Another indication of slowly relaxing heterogeneity in IL solvation structures is the red-edge effect reported in the emission spectra of probe dyes. , …”

Section: Introductionmentioning

confidence: 88%

“…In a glassy environment, the diffusion of probes is non-Gaussian, the mean square displacement (MSD) is best expressed as a power law, 29 and the intermediate scattering function exhibits stretched exponential behavior. 8,9,24,27,28 Another indication of slowly relaxing heterogeneity in IL solvation structures is the red-edge effect reported in the emission spectra of probe dyes. 25,26 The goal of this work was to determine whether there is a correlation between the diffusion rate of a solvatochromic dye (Nile red (NR); Scheme 1) 30−33 behave as conventional solvents that follow the Stokes− Einstein relation.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic and MD Study of Dynamic and Structural Heterogeneities in Ionic Liquids

Kim

Peteanu

2017

J. Phys. Chem. B

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The structure of ionic liquids (ILs) surrounding solute dyes and the effects of solvent structure on solute diffusion have been investigated using molecular dynamics (MD) and the experimental tools of confocal and fluorescence correlation spectroscopies. Although confocal microscopy and simulations show that the local environment around solutes in ILs is heterogeneous and that the structural heterogeneity is rather long-lived, the local polarity and the diffusion constant were found to be uncorrelated. Moreover, the complex diffusion observed experimentally is not due to the structural heterogeneity of the IL but rather due to the dynamic heterogeneity arising from the viscous glassy nature of the IL environment. MD simulations show that the degree of dynamic heterogeneity depends on the first nonvanishing electric multipole moment of the solute. The dynamics of a cationic solute are the least heterogeneous, whereas those of a solute without an electric multipole moment are the most heterogeneous. This indicates that the length scale over which the solute-solvent interactions occur, and thus the number of solvent degrees of freedom that couple to the solute, are the key factors governing the dynamic heterogeneity of the solute.

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Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Spectroscopic and MD Study of Dynamic and Structural Heterogeneities in Ionic Liquids

Kim

Peteanu

2017

J. Phys. Chem. B

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“…In recent years, a great interest has been attracted by a possible relationship between structural and dynamic heterogeneities in ILs 20 21 22 23 33 34 35 36 37 . To consider the crucial issue for better understanding the molecular dynamics of ILs, we have evaluated the dynamic length scales via Eq.…”

Section: Resultsmentioning

confidence: 99%

“…In a few recent years, ionic liquids have been confirmed to be structurally heterogeneous due to the existence of ionic and hydrophobic domains in the molecular systems 20 21 . The dynamic heterogeneity of ionic liquids at room temperature has been preliminarily suggested by using molecular dynamics simulations 22 . Very recently, Zheng et al 23 used the femtosecond IR spectroscopy to elucidate the local structural dynamics in protic alkylammonium-based ionic liquids and argued that these systems are not only structurally but also dynamically heterogeneous.…”

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confidence: 99%

Ionic liquids and their bases: Striking differences in the dynamic heterogeneity near the glass transition

Grzybowska

Grzybowski

Wojnarowska

et al. 2015

Sci Rep

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Ionic liquids (ILs) constitute an active field of research due to their important applications. A challenge for these investigations is to explore properties of ILs near the glass transition temperature Tg, which still require our better understanding. To shed a new light on the issues, we measured ILs and their base counterparts using the temperature modulated calorimetry. We performed a comparative analysis of the dynamic heterogeneity at Tg for bases and their salts with a simple monoatomic anion (Cl–). Each pair of ionic and non-ionic liquids is characterized by nearly the same chemical structure but their intermolecular interactions are completely different. We found that the size of the dynamic heterogeneity of ILs near Tg is considerably smaller than that established for their dipolar counterparts. Further results obtained for several other ILs near Tg additionally strengthen the conclusion about the relatively small size of the dynamic heterogeneity of molecular systems dominated by electrostatic interactions. Our finding opens up new perspectives on designing different material properties depending on intermolecular interaction types.

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“…We have previously studied the potential of this technique in previous our studies. [19] Using this technique, the disadvantage of the narrowness of the measurement area that comes from using a single line laser would be eliminated, and respiratory rate could be assessed robustly for various body types. Meanwhile, Paz-Reyes et al [20] conducted a study of respiration measurement us-ing only an RGB camera without a line laser.…”

Section: Introductionmentioning

confidence: 99%

For a Clinical Application of Optical Triangulation to Assess Respiratory Rate Using an RGB Camera and a Line Laser

Jeong

Song

Lee

et al. 2022

Preprint

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This paper presents a non-contact and unrestrained respiration monitoring system based on the optical triangulation technique. The proposed system consists of a red-green-blue (RGB) camera and a line laser installed to face the frontal thorax of a human body. The underlying idea of the work is that the camera and line laser are mounted in opposite directions, unlike other research. By applying the proposed image processing algorithm to the camera image, laser coordinates are extracted and converted to world coordinates using the optical triangulation method. These converted world coordinates represent the height of the thorax of a person. The respiratory rate is measured by analyzing changes of the thorax surface depth. To verify system performance, we installed the camera and the line laser on the head and foot sides of a bed, respectively, facing toward the center of the bed. Twenty healthy volunteers were enrolled and underwent meas-urement for 100s. Evaluation results show that the optical triangulation-based image processing method demonstrates non-inferior performance to a commercial patient monitoring system with a root-mean-squared error of 0.30rpm and a maximum error of 1rpm (p > 0.05), which implies the proposed non-contact system can be a useful alternative to the conventional healthcare method

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Dynamic Heterogeneity in Room-Temperature Ionic Liquids

Cited by 4 publications

References 61 publications

Spectroscopic and MD Study of Dynamic and Structural Heterogeneities in Ionic Liquids

Spectroscopic and MD Study of Dynamic and Structural Heterogeneities in Ionic Liquids

Ionic liquids and their bases: Striking differences in the dynamic heterogeneity near the glass transition

For a Clinical Application of Optical Triangulation to Assess Respiratory Rate Using an RGB Camera and a Line Laser

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