Approach to The Assessment of Size-Dependent Thermal Properties of Disperse Solutions: Time-Resolved Photothermal Lensing of Aqueous Pristine Fullerenes C60 and C70статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 3 мая 2017 г.
Аннотация:An approach is proposed for the assessment of thermal properties of aqueous pristine fullerene C60 and C70 dispersions (AFDs) at the level of 10–7–10–5 mol L–1 by photothermal (thermal-lens) spectroscopy for their application in medicine and technology. Along with relevant size-characterization techniques—differential scanning calorimetry (DSC) with the Gibbs–Kelvin equation and dynamic light scattering (DLS) techniques—this approach provides the estimation of size-dependent thermal properties of disperse solutions—thermal diffusivity, thermal effusivity [thermal inertia], and thermal conductivity. The values for AFDs under the conditions of the attained thermal equilibrium show good precision, and the cluster size estimations agree with the reference methods. The reconstruction of thermal-lens characteristic time over the course of the blooming of the thermal-lens effect reveals a short increase in the apparent thermal diffusivity. This is accounted for non-equilibrium heat transfer within fullerene clusters upon initial laser heating, which is supported by the independent estimations from widespread methods like high-resolution transmission electron microscopy, DLS, and DSC. Thermophysical pa-rameters of the disperse phase estimated from transient thermal lensing are: thermal diffusivity, 1.6–2.0 × 10–7 m2 s–1 depending on fullerene concentration and up to 3.5 × 10–7 m2 s–1, more than twofold higher than for water; thermal effusivity, 6.7 × 102 J m−2 K−1 s−½, three times lower than for water.