Acoustically induced oscillation and rotation of a large drop in space

A 2.5 cm diameter water drop was successfully deployed and manipulated in a triaxial acoustic resonance chamber during a 240 sec low-gravity SPAR rocket flight. Oscillation and rotation were induced by modulating and phase shifting the signals to the speakers. Portions of the film record were digitized and analyzed. Spectral analysis brought out the n = 2, 3, 4 free oscillation modes of the drop, its very low-frequency center-of-mass motion in the acoustic potential well, and the forced oscillation frequency. The drop boundaries were least-square fitted to general ellipses, providing eccentricities of the distorted drop. The normalized equatorial area of the rotating drop was plotted vs a rotational parameter, and was in excellent agreement with values derived from the theory of equilibrium shapes of rotating liquid drops

Vibrational analysis of cesium on Ru(0001)

We report a high-resolution electron-energy-loss spectroscopy study of the coverage dependence of the Cs-Ru stretch vibration at 300 K. Surprisingly, the frequency of Cs-Ru stretch vibration shifts upward by about 30% with Cs coverage for 0Cs Cs>0.19 is associated with the metallization of the alkali-metal layer including a structural change

Jacobi multipliers, non-local symmetries and nonlinear oscillators

Constants of motion, Lagrangians and Hamiltonians admitted by a family of relevant nonlinear oscillators are derived using a geometric formalism. The theory of the Jacobi last multiplier allows us to find Lagrangian descriptions and constants of the motion. An application of the jet bundle formulation of symmetries of differential equations is presented in the second part of the paper. After a short review of the general formalism, the particular case of non-local symmetries is studied in detail by making use of an extended formalism. The theory is related to some results previously obtained by Krasil'shchi, Vinogradov and coworkers. Finally the existence of non-local symmetries for such two nonlinear oscillators is proved.Comment: 20 page

The Adsorption of Atomic Nitrogen on Ru(0001): Geometry and Energetics

The local adsorption geometries of the (2x2)-N and the (sqrt(3)x sqrt(3))R30^o -N phases on the Ru(0001) surface are determined by analyzing low-energy electron diffraction (LEED) intensity data. For both phases, nitrogen occupies the threefold hcp site. The nitrogen sinks deeply into the top Ru layer resulting in a N-Ru interlayer distance of 1.05 AA and 1.10 AA in the (2x2) and the (sqrt(3)x sqrt(3))R30^o unit cell, respectively. This result is attributed to a strong N binding to the Ru surface (Ru--N bond length = 1.93 AA) in both phases as also evidenced by ab-initio calculations which revealed binding energies of 5.82 eV and 5.59 eV, respectively.Comment: 17 pages, 5 figures. Submitted to Chem. Phys. Lett. (October 10, 1996

Adatom-induced donor states during the early stages of Schottky-barrier formation: Ga, In, and Pb on Si(113)

We performed angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy for the early stages of Schottky-barrier formation of Ga, In, and Pb on Si(113) at room temperature. In the coverage region below 0.1 monolayer a band-bending behavior, typical for donor states, is found. The energies of the adatom-induced donor states in the band gap depend on the adatoms. The Schottky barrier reaches its final value at a coverage of about one monolayer. The values are 0.35 eV above the valence-band maximum for In and Ga and 0.425 eV for Pb. Measurements with Xe interlayers were made to verify that these interfaces are not reactive

Vibrational analysis of the (Cs+CO)‐(2×2) compound layer on Ru(0001)

On a Ru(0001) surface Cs and CO form a very well ordered (Cs+CO)‐(2×2) compound layer whose structure was analyzed recently (Cs on‐top, CO in threefold sites). Here we present a vibrational analysis of the same system using high‐resolution electron energy loss spectroscopy (HREELS), thermal desorption spectroscopy (TDS), and low‐energy electron diffraction (LEED). The bonding of CO to Ru is both local and nonlocal. Two (C–O) stretch frequencies are observed depending on whether there are one or two CO molecules in the 2×2 cell. They change in energy between 155 and 204 meV depending on CO coverage θCO. Setting θmaxCO=1.0, the evolution of the C–O stretch intensities indicates that up to θCO=0.22 the 1‐CO‐(2×2) phase is formed exclusively implying some mobility of the Cs layer. For θCO≳0.22 the 2‐CO‐(2×2) phase grows additionally until at θCO=1.0 only the 2‐CO‐(2×2) phase is found. Two Ru–CO stretch modes are observed for the first time and are assigned to adsorption in the hcp and fcc hollow sites within the 2×2 unit cell. They are very weak in intensity which is attributed to the threefold‐hollow site and some screening in the 2D compound. With CO adsorption a change of the electronic structure of the Cs adlayer is observed; the adlayer loses metallicity and the Cs–Ru stretch becomes visible. Strong changes of the Cs–Ru stretch energies are observed with CO coverage

Band bending in the initial stages of Schottky-barrier formation for gallium on Si(113)

We present angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy results for the Schottky-barrier formation of Ga on p-type Si(113). For the first 0.08 monolayer of Ga, the band bending increases. For higher coverages, it decreases monotonically until it reaches its final value at about 2 monolayers. This change of band bending is found for a Si surface for the first time and supports a recent model calculation. The final barrier height is 0.32±0.10 eV, in good agreement with the values found for low-index surfaces