Dynamic Odd–Even Effect in Liquid n‐Alkanes near Their Melting Points |
| |
| Authors: | Dr. Ke Yang Zhikun Cai Abhishek Jaiswal Dr. Madhusudan Tyagi Prof. Jeffrey S. Moore Prof. Yang Zhang |
| |
| Affiliation: | 1. Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA;2. Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA;3. NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, MD, USA;4. Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA;5. Department of Chemistry, Department of Materials Science and Engineering, Beckman Institute for Advanced Science and TechnologyUniversity of Illinois at Urbana-Champaign;6. Department of Nuclear, Plasma, and Radiological Engineering, Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA |
| |
| Abstract: | n‐Alkanes are the textbook examples of the odd–even effect: The difference in the periodic packing of odd‐ and even‐numbered n‐alkane solids results in odd–even variation of their melting points. However, in the liquid state, in which this packing difference is not obvious, it seems natural to assume that the odd–even effect does not exist, as supported by the monotonic dependence of the boiling points of n‐alkanes on the chain length. Herein, we report a surprising odd–even effect in the translational diffusional dynamic properties of n‐alkanes in their liquid states. To measure the dynamics of the molecules, we performed quasi‐elastic neutron scattering measurements near their melting points. We found that odd‐numbered n‐alkanes exhibit up to 30 times slower dynamics than even‐numbered n‐alkanes near their respective melting points. Our results suggest that, although n‐alkanes are the simplest hydrocarbons, their dynamic properties are extremely sensitive to the number of carbon atoms. |
| |
| Keywords: | alkanes molecular dynamics odd– even effect quasi-elastic neutron scattering relaxation times |
|
|
