The dissociation onset for halogen atom loss was investigated for 2-iodo and 2-chloropropane ions using a newly developed threshold photoelectron photoion coincidence (TPEPICO) technique that suppresses the effects of hot electrons. This study was undertaken in order to resolve current discrepancies concerning these onsets in the literature. The 0 K dissociation thresholds were determined to be 9.818 ± 0.010 and 11.036 ± 0.010 eV for 2-C 3 H 7 I and 2-C 3 H 7 Cl, respectively. These numbers agree quite well with photoionization and a mass analyzed threshold ionization (MATI) study, but are significantly lower than onsets measured by the much higher resolution pulsed field ionization PEPICO method. The derived C 3 H 7 + heat of formation at 298 K is 803.9 ± 1.5 kJ mol-1 , and a more precise value for the 298 K 2-iodopropane heat of formation is-40.8 ± 1.3 kJ mol-1. The derived proton affinity of propene is 746.1 kJ mol-1. We have also performed a high-level ab initio calculation on the 0 K dissociation limit, E 0 , for C 3 H 7 + from C 3 H 7 Cl at the CCSD(T)/CBS level of theory with high-level corrections. The theoretical prediction of 11.048-11.061 eV for E 0 (C 3 H 7 +) from C 3 H 7 Cl is found to be consistent with the current experimental value.

We present experimental observations and quantified theoretical predictions of the nanoscale hydrodynamics induced by nanorod precession emulating primary cilia motion in developing embryos. We observe phenomena including micron size particles which exhibit epicyclic orbits with coherent fluctuations distinguishable from comparable amplitude thermal noise. Quantifying the mixing and transport physics of such motions on small scales is critical to understanding fundamental biological processes such as extracellular redistribution of nutrients. We present experiments designed to quantify the trajectories of these particles, which are seen to consist of slow orbits about the rod, with secondary epicycles quasicommensurate with the precession rate. A first-principles theory is developed to predict trajectories in such time-varying flows. The theory is further tested using a dynamically similar macroscale experiment to remove thermal noise effects. The excellent agreement between our theory and experiments confirms that the continuum hypothesis applies all the way to the scales of such submicron biological motions.

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