A dynamic calibration technique for temperature programmed desorption spectroscopy.

A novel, rapid and accurate calibration procedure as a means for quantitative gas desorption measurement by temperature programmed desorption (TPD) spectroscopy is presented. Quantitative measurement beyond the linear regime of the instrument is achieved by associating an instantaneous calibrated molar flow rate of gas to the detector response. This technique is based on fundamental methods, and is independently verified by comparison to the hydrogen desorption capacity of a known standard metal hydride with known stoichiometry. The TPD calibration procedure described here may be used for any pure gas, and the accuracy is demonstrated for the specific case of hydrogen.

Intrinsic and extrinsic effects in the temperature-dependent photoluminescence of semiconducting carbon nanotubes.

The temperature dependence of the band gap of semiconducting carbon nanotubes was measured for ten different nanotube species. The unprecedented effectiveness in avoiding the effect of external strain, or any other effects originating from the surrounding environment, lead to an accurate measurement of the band gap temperature dependence, giving fundamental insight into the nanotube electron-phonon interaction. Small but reproducible energy shifts of the emission lines with temperature were observed, showing a moderate chirality dependence, well in agreement with recent theoretical calculations. In addition to the energy shift, a substantial narrowing of the emission lines was also observed. The removal of the temperature shift of the band gap allows the precise measurement of the effect of external strain on carbon nanotubes in different environments.

Hydrogen storage in novel organometallic buckyballs.

Transition metal (TM) atoms bound to fullerenes are proposed as adsorbents for high density, room temperature, ambient pressure storage of hydrogen. C60 or C48B12 disperses TMs by charge transfer interactions to produce stable organometallic buckyballs (OBBs). A particular scandium OBB can bind as many as 11 hydrogen atoms per TM, ten of which are in the form of dihydrogen that can be adsorbed and desorbed reversibly. In this case, the calculated binding energy is about 0.3 eV/H(2), which is ideal for use on board vehicles. The theoretical maximum retrievable H2 storage density is approximately 9 wt %.

Nanotube wires on commensurate InAs surfaces: binding energies, band alignments, and bipolar doping by the surfaces.

Using first-principles methods, we study the physicochemical properties such as the binding mechanism and band offset for single-wall zigzag nanotubes on InAs. While the tubes maintain their structural and electronic integrity, binding energies as large as 0.4 eV per site are obtained. Except for semiconducting tubes on the polar surfaces, an approximate universal band alignment is also obtained. The exception is due to large surface dipoles. In fact, polar (111) and (1;1;1;) surfaces have opposite dipoles that cause autodoping of a (14,0) tube to the n and the p type, respectively, without actual dopant.

Fabrication and use of nanometer-sized electrodes in electrochemistry.

Electrodes with electrochemical dimensions as small as 10 angstroms have been fabricated and used for electrochemical studies. These nanometer-scale electrodes have enabled the measurement of electron-transfer rate constants, k(het), that are two orders of magnitude faster than k(het) values accessible with any other electrochemical method.

Analysis of the published calorimetric evidence for electrochemical fusion of deuterium in palladium.

Estimates are given of the raw data that are the basis for the claims of excess power production by the electrochemical charging of palladium in deuterium oxide (D(2)O). Calorimetric results are also presented that show no anomalous power production in either 0.1M LiOD/D(2)O or 0.1M LiOH/H(2)O (LiOH is lithium hydroxide). Several possible sources of error in open-system calorimetry are discussed that can confound interpretation of temperature changes in terms of anomalous power production.