Rescattering double ionization of D2 and H2 by intense laser pulses

We have measured momentum spectra and branching ratios of charged ionic fragments emitted in the double ionization of D2 (and H2) molecules by short intense laser pulses. We find high-energy coincident D+ (and H+) ion pairs with kinetic energy releases between 8 and 19 eV which appear for linearly polarized light but are absent for circularly polarized light. The dependence on the polarization, the energy distributions of the ions, and the dependence on laser intensity of yield ratios lead us to interpret these ion pairs as due to a rescattering mechanism for the double ionization. A quantitative model is presented which accounts for the major features of the data.     

The surface properties of tetradecyltrimethylammonium bromide observed by capillary electrophoresis

The electroosmotic flow (EOF) is measured as a function of tetradecyltrimethylammonium bromide (TTAB) concentration and is shown to have distinct zones that are pH dependent. The data is correlated with previously proposed surface structures ranging from unimolecular adsorption to hemimicelles and micelles of TTAB adsorbed on the hydrated fused silica. A plot of the TTAB concentration at zero EOF versus pH shows that the zero point of charge (zpc) is pH dependent and that a linear extrapolation of the data intercepts close to the pH value for the zpc of a fused-silica surface. This shows that different surface properties at different pH values at any given TTAB concentration are generally dealt with. Therefore, these pH-dependent structures of the fused-silica surface have to be taken into account while studying these phenomena.     

Photoelectron-photoion momentum spectroscopy as a clock for chemical rearrangements: isomerization of the di-cation of acetylene to the vinylidene configuration

We have used complete correlated momentum mapping of the photoelectron and heavy ion products from the dissociation of the di-cation of acetylene, induced by photoionizing the carbon K shell of one of the atoms, to map out the angular correlation between the electron and the axis of the target molecule. The (quasi-) symmetric decay is found to proceed through both acetylene and vinylidene configurations. By using the strongly peaked photoelectron emission to "start a clock," an upper limit of 60 fs is placed on the isomerization time from the acetylene to the vinylidene configuration.     

Strong correlations in the He ground state momentum wave function observed in the fully differential momentum distributions for the p + He transfer ionization process

The four-particle process of proton-helium transfer ionization has been studied using cold target recoil ion momentum spectroscopy to measure the momenta of all three particles in the final state. Most of the electrons are emitted in the H0 scattering plane and in the backward direction. The final state momentum distributions show discrete structures very different from those expected for uncorrelated capture and ionization. The measured momentum pattern is interpreted to be due to a new transfer ionization reaction channel which results from strong correlations in the initial He ground state momentum wave function.     

High temperature Knudsen cell mass spectrometric determination of the heats of atomization of AlAu2 and Al2Au

The atomization energies, ΔH⁰_at,0 of the molecules, AlAu₂ and Al₂ and Al₂Au have been determined as 121 ± 6 and 110 ± 5 kcal mole^?1 or 506.3 ± 25.1 and 460.2 ± 20.9 kJ mole^?1, respectively.Theses atomization energies are discussed in terms of bond strengths and the Pauling model of a polar bond. Available information suggests that AlAu₂ has the structure AuAlAu, but that Al₂Au has the structure AlAlAu. For both molecules divalent gold is shown to be unlikely.     

Information and gravitation

An information-theoretic approach is shown to derive both the classical weak-field equations and the quantum phenomenon of metric fluctuation within the Planck length. A key result is that the weak-field metric is proportional to a probability amplitude φ_uv, on quantum fluctuations in four-position. Also derived is the correct form for the Planck quantum length, and the prediction that the cosmological constant is zero. The overall approach utilizes the concept of the Fisher information I acquired in a measurement of the weak-field metric. An associated physical information K is defined as K=I−J, where J is the information that is intrinsic to the physics (stress-energy tensor T_μv) of the measurement scenario. A posited conservation of information change δI=ΔJ implies a variational principle δK=0. The solution is the weak-field equations in the metric and associated equations in the probability amplitudes φ_uv. The gauge condition φ _v ^uv =0 (Lorentz condition) and conservation of energy and momentum T_v ^μv=0 are used. A well-known “bootstrapping” argument allows the weak-field assumption to be lifted, resulting in the usual Einstein field equations. A special solution of these is well known to be the geodesic equations of motion of a particle. Thus, the information approach derives the classical field equations and equations of motion, as well as the quantum nature of the probability amplitudes φ_uv.