Inversion of two-band superconductivity at the critical electron doping of (Mg, Al)B2.

Electron energy-loss spectroscopy (EELS) was combined with heat capacity measurements to probe changes of electronic structure and superconductivity in Mg(1-x)Al(x)B(2). A simultaneous decrease of EELS intensity from sigma-band hole states and the magnitude of the sigma gap was observed with increasing x, thus verifying that band filling results in the loss of strong superconductivity. These quantities extrapolated to zero at x approximately 0.

Thermal conductance and wettability of xenon on resorcinol-formaldehyde aerogels.

We have performed thermal conductivity and adsorption isotherm measurements to investigate the system formed by Xe adsorbed on resorcinol-formaldehyde (RF) aerogel. Below 80 K, the thermal conductivity of the Xe/RF-aerogel system is essentially identical to that of the bare RF aerogel; however, above this temperature the thermal conductivity of the system increases significantly above that of the bare aerogel. Adsorption isotherm measurements indicate that Xe incompletely wets the RF aerogel below Xe's bulk triple point temperature.

Gases Do not adsorb on the interstitial channels of closed-ended single-walled carbon nanotube bundles.

We have experimentally determined the binding energies of Xe, CH4, and Ne on samples of closed-ended single-wall nanotube (SWNT) bundles. We find values for these quantities which are larger by approximately 75% on the SWNT samples than the values found for the same adsorbates on planar graphite. We have also determined the monolayer capacity of a SWNT sample using Xe and Ne adsorption.