Concentration fluctuations and microheterogeneity in aqueous amide mixtures (CROSBI ID 149167)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Zoranić, Larisa ; Mazighi, Redha ; Sokolić, Franjo ; Perera, Aurélien
engleski
Concentration fluctuations and microheterogeneity in aqueous amide mixtures
The relationship between concentration fluctuations and the microheterogeneous status of aqueous amide mixtures is addressed through the molecular dynamics study of three different amides, namely, formamide, N-methylformamide, and dimethylformamide. The computer simulations provide structural evidence that these mixtures exhibit considerable microheterogeneity, in apparent contrast to the experimentally obtained Kirkwood– Buff integrals which indicate that these mixtures should be near ideal. This contradiction is addressed by distinguishing microheterogeneity from concentration fluctuations. The former is the result of mixing H-bonding species under specific constraints due to various bonding possibilities between the molecules, while the second is related to the average relative distribution of the molecules. The relationship between these two different quantities is analyzed and illustrated in terms of the partial site-site structure factors. Small wave-number prepeaks relate to the microheterogeneity while zero wave-number value relates to the concentration fluctuations. A simple analytical statistical model for the microheterogeneity is formulated, which allows to discuss the small wave-number behavior of these structure factors in terms of the kinetics of the transient cluster formation, as observed in the computer simulations.
concentration fluctuations ; microheterogeneity ; aqueous amide
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
Podaci o izdanju
130 (12)
2009.
124315
12
objavljeno
0021-9606
1089-7690
10.1063/1.3093071