Self-normalized laws of the iterated logarithm

Abstract Stronger versions of laws of the iterated logarithm for self-normalized sums of i.i.d. random variables are proved

Size-Dependent Kinetics of Hydriding and Dehydriding of Pd Nanoparticles

Using a new indirect nanoplasmonic sensing method with subsecond resolution, we have studied hydriding and dehydriding kinetics of Pd nanoparticles in the size range 1.8-5.4 nm. Strong particle-size effects are observed. The scaling of the hydriding and dehydriding time scales satisfies power and power-exponential laws. The former (with an exponent of 2.9) is in perfect agreement with Monte Carlo simulations of diffusion-controlled hydriding kinetics. The latter is explained by the effect of surface tension on hydrogen desorption from the surface layer. The approach is generalizable to other reactant-nanoparticle systems

Thermodynamics of hydride formation and decomposition in supported sub-10 nm Pd nanoparticles of different sizes

Hydrogen storage properties of supported Pd nanoparticles with average sizes in the range 2.7-7.6 nm were studied using indirect nanoplasmonic sensing. For each particle size, a series of isotherms was measured and, through Van't Hoff analysis, the changes in enthalpy upon hydride formation/decomposition were determined. Contrary to the expected decrease of the enthalpy, due to increasing importance of surface tension in smaller particles, we observe a very weak size dependence in the size range under consideration. We attribute this to a compensation effect due to an increased fraction of hydrogen atoms occupying energetically favorable subsurface sites in smaller nanoparticles