Volume 111, Issue 5, 01 August 1999
Index of content:
111(1999); http://dx.doi.org/10.1063/1.479507View Description Hide Description
Site effects on the molecular hydrogen elimination from propane at 157 nm excitation have been studied using the photofragment translational spectroscopic technique. Experimental results indicate that elimination from the internal carbon of propane (2,2-elimination) is predominant while eliminations from the terminal carbon (1,1- and 1,3-elimination) and the vicinal carbons (1,2-elimination) are minor. The translational energy distributions obtained for these processes also show that the dynamics of eliminations from different sites are significantly different. Relative branching ratios of the atomic hydrogen (H) and the molecular hydrogen elimination processes were also determined.
111(1999); http://dx.doi.org/10.1063/1.479448View Description Hide Description
A microscopic theory is presented for the behavior of polyelectrolyte solutions between surfaces. The theory predicts oscillatory forces between hydrophobic surfaces immersed in dilute salt-free polyelectrolyte solutions. The period of the oscillation, p, scales with concentration, ρ, as and in the dilute and semidilute solutions, respectively. With a small amount of excess salt, the oscillatory forces are replaced by a short-ranged, predominantly attractive force. Further addition of salt causes the force to become purely repulsive. These predictions can, in principle, be tested experimentally.