The temperature dependent structure of liquid 1-propanol as studied by neutron diffraction and EPSR simulations
Artikel i vetenskaplig tidskrift, 2013

The structure of liquid 1-propanol is investigated as a function of temperature using neutron diffrac- tion together with Empirical Potential Structure Refinement modelling. The combined diffraction and computer modelling analysis demonstrates that propanol molecules form hydrogen bonded clusters with a relatively wide size distribution, which broadens at lower temperatures. We find that the clus- ter size distribution is well described by a recently proposed statistical model for branched H-bonded networks [P. Sillrén, J. Bielecki, J. Mattsson, L. Börjesson, and A. Matic, J. Chem. Phys. 136, 094514 (2012)]. The average cluster size increases from ∼3 to 7 molecules, whilst the standard deviation of the size distribution increases from 3.3 to 8.5 as the temperature is decreased from 293 to 155 K. The clusters are slightly branched, with a higher degree of branching towards lower temperatures. An analysis of the cluster gyration tensor (Rmn) reveals an average elongated ellipsoidal shape with axes having proportions 1:1.4:1.9. We find that the average radius of gyration has a cluster size dependence consistent with that of fractal clusters, Rg ∝ n1/D , with a fractal dimension D ≈ 2.20, which is close to D = 2.00 expected for an ideal random walk or D = 2.11 expected for reaction limited aggregation. The characteristic angles between the H-bonded OH-groups that constitute the clusters show only a weak temperature dependence with O–H· · ·O angles becoming more narrowly distributed around 180◦ at lower temperatures.

hydrogen bonding

Neutron Diffraction

propanol

Författare

Per Sillrén

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Jan Swenson

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Johan Mattsson

University of Leeds

D.T. Bowron

ISIS Facility

Aleksandar Matic

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Journal of Chemical Physics

0021-9606 (ISSN) 1089-7690 (eISSN)

Vol. 138 214501- 214501

Ämneskategorier

Fysik

Den kondenserade materiens fysik

DOI

10.1063/1.4807863