| Abstract
| - Deuterium NMR spectroscopy has been used to probe the dynamics of deuterated octadecylphosphonate(−1,1−d2) (ODPA−d2) monolayers on nonporous ZrO2 powder (surface area ≈ 40 m2/g) over the temperaturerange of 200−340 K. At 200 K, a broadened Pake doublet with distinct nonrigid characteristics and a hornsplitting of approximately 120 kHz was observed. With increasing temperature, the 2H spectrum graduallytransforms into a relatively narrow and featureless peak. Spectral simulations are performed with the help ofplausible motional models, and the results show that, over the whole temperature range studied, the C1−Dbonds have substantial motional freedom with respect to the characteristic 2H NMR time scale. In addition,at each temperature, a weighted superposition of several simulated line shapes with different rates and sitepopulations is required to account for the observed spectral features, indicating the presence of considerablemotional heterogeneity within the ODPA monolayers. The results are further discussed in terms of the knowncharacteristics of the ZrO2 surface and of the conformational transitions in the octadecyl chain.
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