Study of translational self-diffusion of molecules in liquids

How mobile are dye adsorbates and acetonitrile molecules on the surface of TiO2 nanoparticles? A quasi-elastic neutron scattering study

“…The following self-diffusion coefficients are obtained at 250 K, 270 K and 290 K: D trans  = 2.41 ± 0.02 × 10 −5  cm 2  s −1 , 3.12 ± 0.05 × 10 −5  cm 2  s −1 and 3.95 ± 0.07 × 10 −5  cm 2  s −1 (see also Table S1 for the time constants corresponding to the plateaus at high Q values which can be interpreted in terms of expected methyl group rotation). The resulting Arrhenius activation energy of these values is 0.08 eV, enabling us to confirm by extrapolation that the diffusion coefficients we observe are consistent with those derived previously for acetonitrile at 298 K with QENS ( D 298K  = 4.2 ± 0.2 × 10 −5  cm 2  s −1 )4043 and NMR ( D 298K  = 4.04 × 10 −5  cm 2  s −1 )44.…”

Self-Diffusion in Molecular Fluids and Noble Gases: Available Data

“…All of them correspond to liquids and were determined by the SFG, except the carbon tetrachloride of Fischer and Weiss, that could be measured by PFG as well. We have placed here ten of the twenty-one substances analyzed by Samigullin, which were also represented graphically, but are not readable due to some deformation in the y axis of the figures (and detected because a considerable disagreement between the obtained values and those calculated by the formulas). Unlike Table , where there were no functions of T and/or P , all data in this table are given in terms of activation energies ( ), activation volumes ( ) and preexponential factors ( ), defined as is commonly replaced by a value of 11 at atmospheric pressure and at one reference temperature.…”

“…Finally, several misprints and mistakes in the consulted literature have been found: Dupré et al and Anderson and Gerritz said that they calibrated their devices with the water of Hausser et al at 293.16 K and with the dodecanol of McCall et al, respectively, but the points of Hausser are only available above 298.16 K and McCall did not measure 11 for dodecanol; the helium diffusivities in the Figure of Luszczynski et al are multiplied by 10 2 instead of by 10 3 , glycerol points of Hrovat and Wade below 313.16 K are also wrongly multiplied by 10 9 instead of by 10 8 ; some captions of the tables of Bachl are displaced (we identified the correct disposition by comparing the numbers with the figures of the thesis); Panchenkov et al and Samigullin investigated the dichloroethane, but they did not specify the isomer (1,2-dichloroethane, 1,1-dichloroethane, or a mixture of both); and Fury et al calibrated their device by erroneously assuming that the pyridine of O’Reilly was pyridine- d 5 (in fact, they previously rejected a value of 1.74·10 –9 m 2 ·s –1 at 303.16 K and 0.1 MPa, obtained by evaluating G through the shape of the spin echo, which is in good agreement with the diffusivities of Holz et al for the deuterated compound), so their results for pyridine- d 5 are higher than expected.…”