Raman Spectroscopy of Conformational Rearrangements at Low Temperatures : Folding and Stretching of Alkanes in Supersonic Jets
Overview
This thesis identifies the turning point in chain length, after which alkanes self-solvate into a folded structure instead of an extended stretched conformation. After this turning point, London dispersion forces rearrange isolated n-alkanes into a particular hairpin-structure, while for shorter chain lengths, a simple stretched conformation is energetically preferred. This thesis can locate the experimental turning point for the first time in an interaction-free manner from measurements of unbranched alkanes at low temperatures in supersonic jet expansions. It contains a detailed analysis of the vibrational Raman spectra of the chain molecules, which is supported by comprehensive quantum chemical simulations. In this way, the detailed balance between inter-chain attraction and conformational flexibility can be quantified. The investigations are complemented by measurements of perfluoroalkanes and similarities and differences between the compounds are discussed. Furthermore, Nils L ttschwager determines the stiffnesses (elastic moduli) of two of the most common industrial polymers: polyethylene and polytetrafluorethylene. He uses in this thesis a sophisticated extrapolation to calculate this value from quantities of their building blocks, showing that the single polymer molecules can be as stiff as a rod of steel.
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Details
- ISBN-13: 9783319359762
- ISBN-10: 3319359762
- Publisher: Springer
- Publish Date: September 2016
- Dimensions: 9.21 x 6.14 x 0.42 inches
- Shipping Weight: 0.62 pounds
- Page Count: 183
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