Translational diffusion process of charged radicals: N,N,N′,N′-tetramethyl-p-phenylenediamine and its cation radical

Terazima, Masahide; Okazaki, Toshiya; Hirota, Noboru

doi:10.1016/1010-6030(95)04154-2

Cited by 22 publications

(15 citation statements)

References 41 publications

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“…The interface selectivity was achieved by the probe reflection at the interface. 21,30,31 Under this experimental configuration, analysis of the dynamics should be much simpler compared with the case of the short penetration depth, because the transport of the thermal energy or molecules along the vertical direction to the grating vector is minor. Most of the TG dynamics is determined by the transport along the grating vector.…”

Section: A Forced Light Scatteringmentioning

confidence: 99%

“…This behavior is very different from the forced Rayleigh scattering signal from the solid-liquid interface, at which the signal quickly decays nonexponentially. 30 The profile from the solid-liquid interface was explained in terms of the very rapid thermal diffusion from the liquid phase to the solid phase. 30 The single exponential decay at the gas-liquid interfaces results from the slow thermal energy transport from the liquid to gas phase.…”

Section: Thermal Diffusion At the Interfacesmentioning

confidence: 99%

“…30 The profile from the solid-liquid interface was explained in terms of the very rapid thermal diffusion from the liquid phase to the solid phase. 30 The single exponential decay at the gas-liquid interfaces results from the slow thermal energy transport from the liquid to gas phase. The decay rates from 2-propanol surface are plotted in Fig.…”

Section: Thermal Diffusion At the Interfacesmentioning

confidence: 99%

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Surface and molecular dynamics at gas-liquid interfaces probed by interface-sensitive forced light scattering in the time domain

1999

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The forced Brillouin and Rayleigh scattering techniques under the probe reflected transient grating configuration were used to probe various dynamics at gas-liquid interfaces in the time domain over the wave-number range of 0.2ϫ10 6 ϳ2.0ϫ10 6 m Ϫ1 . From the forced Brillouin scattering signal, the temporal behaviors of the capillary wave ͑CW͒ were investigated. The observed wave does not consist of one sine or cosine wave but shows dual features. This feature was explained in terms of two mechanisms of the capillary wave creation by the photothermal effect; the thermal expansion and the temperature dependence of the surface tension. Besides the oscillatory behavior for nonviscous liquids, a heavily damped capillary wave was observed in a range of wave number above 1.6ϫ10 6 m Ϫ1 from a viscous liquid ͑1-hexanol͒ surface, which has never been detected before. The observed signals were compared with the phenomenologically expressed wave forms and the theoretically calculated wave forms based on the hydrodynamic equations. For CW on the organic liquid surface, the hydrodynamic equation predicts the observed temporal profile well, whereas the agreement is less satisfactory for CW on water surface. Using the theoretical equations, the surface motion as well as liquid motion beneath the surface under the forced light scattering condition is presented. The temporal profile of the forced Rayleigh scattering signal provides information on the thermal diffusivity and molecular movement at the surface. The thermal diffusivity at the surface region is found to be very close to that in the bulk phase, whereas the molecular motion at the surface is revealed to be faster than that in the bulk phase. The faster movement at the surface may be explained by the transverse motion of the surface by CW.

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Section: A Forced Light Scatteringmentioning

confidence: 99%

Section: Thermal Diffusion At the Interfacesmentioning

confidence: 99%

Section: Thermal Diffusion At the Interfacesmentioning

confidence: 99%

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Surface and molecular dynamics at gas-liquid interfaces probed by interface-sensitive forced light scattering in the time domain

1999

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“…They reported that the hydrogen bonding between the OH or NH2 group of a solute molecule and polar solvents makes the diffusion process very slow. Radicals are interesting systems for diffusion studies as well as for elucidating the mechanism [379]. The results showed that the cation radicals diffuse only half as quickly as the parent molecule in ethanol, the contribution of the charge and the unpaired electron could not be separated from this measurement.…”

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confidence: 74%

Electron‐transfer Reactions of Aromatic Compounds

Gescheidt¹,

Khan²

2001

Electron Transfer in Chemistry

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Aromatic molecules are inclined to undergo electron-transfer reactions. The additional charges introduced by the electron-transfer process are efficiently stabilized by delocalization. Nevertheless rearrangements of the molecular skeleton or followup reactions can occur. The course of the electron-transfer reactions and the properties of the species thus formed are the subject of this section.In particular, we concentrate on the species formed after an one-electron transfer reaction. Starting from closed-shell diamagnetic precursors, paramagnetic stages, i.e. radical cations or radical anions are formed in this first step. To understand the properties and reactivity of these species, detailed knowledge in terms of charge and spin delocalization and electronic structure is an important prerequisite. This information is preferably derived from electronic and paramagnetic resonance (EPR and electron-nuclear multiple resonance-techniques such as ENDOR or Triple spectroscopy). It has recently been shown that the experimental results can be substantiated by the use of quantum-chemical calculations. In addition to Hartree-Fock-based ab initio procedures, calculations on the density-functional level of theory have been established as rather efficient tools. Therefore, before representing examples of electron-transfer-generated radicals a short survey of the computational methods is given.Another substantial factor directing the kinetic and thermodynamic stability of charged radicals is ion pairing. This phenomenon, although well established for many years, is often not directly distinct in experiments. To establish the importance of ion pairing, or, in other words, supramolecular interactions, a separate introductory chapter is dedicated to these aspects.The references are selected particularly from recent publications, without, however, ignoring some 'classical' contributions. In some sections topics are included which do not strictly represent aromatic molecules but involve interactions of ztype orbitals.

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“…Our technique uses photothermal spectroscopy and fiber Bragg grating sensors (FBGs) to monitor the environment of pH-sensitive chromophores. [20] FBGs are currently being studied for a number of sensing applications, many focusing on either temperature or strain. [21] Heat changes, resulting from light absorption by a chromophore, are measured with a fiber Bragg grating [22] (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

A photonic pH sensor based on photothermal spectroscopy

Hartings¹,

Castro²,

Gill³

et al. 2019

Sensors and Actuators B: Chemical

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Although the determination of pH is a standard laboratory measurement, new techniques capable of measuring pH are being developed to facilitate modern technological advances. Bio-industrial processing, tissue engineering, and intracellular environments impose unique measurement requirements on probes of pH. We describe a fiber optic-based platform, which measures the heat released by chromophores upon absorption of light. The optical fibers feature fiber Bragg gratings (FBG) whose Bragg peak redshifts with increasing temperature. Using anthocyanins (pH-sensitive chromophores found in many plants), we are able to correlate visible light absorption by a solution of anthocyanins to heat released and changes in FBG signal over a pH range of 2.5 to 10. We tested the ability of this platform to act as a sensor coating the fiber within a layer of crosslinked polyethylene glycol diacrylate (PEG-DA). Incorporating the anthocyanins into the PEG, we find that the signal magnitude increases over the observed signal at the same pH in solution. Our results indicate that this platform is viable for assessing pH in biological samples and point at ways to optimize performance.

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Translational diffusion process of charged radicals: N,N,N′,N′-tetramethyl-p-phenylenediamine and its cation radical

Cited by 22 publications

References 41 publications

Surface and molecular dynamics at gas-liquid interfaces probed by interface-sensitive forced light scattering in the time domain

Surface and molecular dynamics at gas-liquid interfaces probed by interface-sensitive forced light scattering in the time domain

Electron‐transfer Reactions of Aromatic Compounds

A photonic pH sensor based on photothermal spectroscopy

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