Viscosities of some organic glasses used as trapping matrixes

Ling, A. Campbell; Willard, John E.

doi:10.1021/j100852a010

Cited by 153 publications

(80 citation statements)

References 4 publications

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“…Two sets of viscosities were used for MTHF: one, from ref 15, was for 183.2–383.2 K (0.236 cP ≤ η ≤ 2.38 cP) with uncertainties less than ±2%. The other, from ref 21 (with the correction noted in ref 20), was for 97.5–107.5 K (2.1 × 10 5 cP ≤ η ≤ 1.8 × 10 9 cP) with somewhat larger uncertainties; the temperatures were given to the nearest 0.5 K and η was said to change by an order of magnitude for Δ T = 2 K. Because there also is a substantial gap between the viscosities for 183.2 K (2.98 cP) 15 and 107.5 K (2.1 × 10 5 cP), 21 VTF fits were made for the combined viscosities from refs 15 and 21 and for only the viscosities from ref 15; the rms error for the latter was clearly smaller (Table 2). …”

Section: Methodsmentioning

confidence: 99%

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)₂⁻

et al. 2010

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Electron spin resonance studies of the planar bis(maleonitriledithiolato)nickel complex ion, Ni(mnt)2−, have been carried out from the motional narrowing region to the glassy limit in a series of ethers: 2-methyltet-rahydrofuran (MTHF), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme). Analyses of the spectra show that Ni(mnt)2− is reorienting a factor of 3 faster about its long in-plane axis in all of these solvents; i.e., axially symmetric rotational diffusion produces agreement between the experimental and calculated line widths with D||/D⊥= 3.0 ± 0.2; D|| and D⊥ are the diffusion constants for reorientation about the long in-plane (parallel) and perpendicular axes, respectively. The temperature dependence of the reorientational correlation time τ2(0) = (6D⊥)−1 determined from the widths is in agreement with the modified Stokes–Einstein–Debye model; the results indicate that Ni(mnt)2− has relatively strong (but not associative) interactions with the ethers. The experimental values of τ2(0) and the solvents’ viscosities, self-diffusion constants, and dielectric relaxation times are compared and found to have a common temperature dependence. The ESR data also are compared with values of 〈τ〉solv, the correlation time obtained when a fluorescent probe is excited and its emission is monitored as the nonequilibrium solvent distribution relaxes. 〈τ〉solv and τ2(0) are found to have a common temperature dependence in MTHF, tetraglyme, and two other solvents (ethyl alcohol and 1-butanol) in which Ni(mnt)2− has been studied. The factors determining these transport properties are discussed.

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Section: Methodsmentioning

confidence: 99%

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)₂⁻

et al. 2010

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“…From the series methanol to 1-octanol which has been measured we present here the data for ethanol and 1-propanol ͑together with viscosity literature data 25,26 ͒ again in a ͓d log(x)/d(1/T)͔ Ϫ1/2 vs 1/T representation in Fig. 14 and Fig.…”

Section: Alcoholsmentioning

confidence: 99%

Dynamics of glass-forming liquids. II. Detailed comparison of dielectric relaxation, dc-conductivity, and viscosity data

Stickel

Fischer

Richert

1996

The Journal of Chemical Physics

517

430

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We have studied the temperature dependence of dielectric relaxation times in terms of the peak frequency f max (T) of dielectric loss ⑀Љ͑͒ and the dc-conductivity dc (T) of several glass-forming liquids, covering 12 decades in the peak frequency f max and 9 decades in dc . Although dc-conductivity samples the mobility of ionic tracers, its variation with temperature is similar to that of f max (T). The f max (T) and dc (T) are analyzed using the temperature-derivative method and compared to the viscosity data Ϫ1 (T). While most liquids reveal a common Vogel-FulcherTammann ͑VFT͒ behavior for f max , dc and Ϫ1 in an extended temperature range TуT m , some liquids deviate from this behavior by displaying a crossover at TϭT A to an Arrhenius regime. In these cases the quantity f max (T) decouples from the common curves for dc (T) and Ϫ1 (T) and attains activation energies in excess ͑ϳ40% for alcohols͒ of those related to translational processes. For many samples a departure from the VFT behavior occurs at lower temperatures T B ϽT m which tends to retard the glass transition. The onset of this qualitative change in the temperature dependence at T B turns out to be a characteristic temperature also in other experiments.

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“…It belongs to a group of molecules referred to as branched-chain alkanes [11] or as methylated alkanes [12]. It is a nonpolymeric glass-forming liquid with a calorimetric glass transition temperature at T G ≈ 77 K [13][14][15]. The glassy phase is readily formed by cooling the * giacomo.baldi@cnr.it liquid below the glass transition temperature, thus allowing us to study the behavior of both liquid and disordered solid phases.…”

Section: Introductionmentioning

confidence: 99%

Collective excitations in liquid and glassy 3-methylpentane

et al. 2015

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We present a detailed investigation of the terahertz vibrational dynamics of 3-methylpentane performed by means of high-resolution inelastic x-ray scattering (IXS). We probe the dynamics in a large temperature range, which includes the glass, the supercooled liquid, and the liquid phases. The characteristic frequency of the excitations follows a well-defined dispersion curve extending beyond 8 nm −1 at all the investigated temperatures, indicating the persistence of a solidlike behavior also in the liquid phase. This implies the existence of a pseudo-Brillouin zone whose size compares surprisingly well with the periodicity inferred from the first sharp diffraction peak in the static structure factor. We show that, in the investigated temperature range, both sizes undergo a variation of about 15%-20%, comparable to that of the average intermolecular distance. We finally show that the IXS sound velocity coincides with the infinite frequency sound velocity previously inferred from visible and ultraviolet Brillouin spectroscopy data. This analysis confirms the role of the shear relaxation processes in determining the variation with frequency of the apparent sound velocity.

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Viscosities of some organic glasses used as trapping matrixes

Cited by 153 publications

References 4 publications

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)₂⁻

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)₂⁻

Dynamics of glass-forming liquids. II. Detailed comparison of dielectric relaxation, dc-conductivity, and viscosity data

Collective excitations in liquid and glassy 3-methylpentane

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Viscosities of some organic glasses used as trapping matrixes

Cited by 153 publications

References 4 publications

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)2−

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)2−

Dynamics of glass-forming liquids. II. Detailed comparison of dielectric relaxation, dc-conductivity, and viscosity data

Collective excitations in liquid and glassy 3-methylpentane

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Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)₂⁻

Electron Spin Resonance Studies of the Reorientational Motion of Ni(mnt)₂⁻