k-Restoring processes at carbon depleted ultralow-k surfaces

In this study we investigate the silylation of OH groups with different silazanes. In particular we use density functional theory and the nudged elastic band method to study the different reaction mechanisms. For the silylation reaction of hexamethyldisilazane and trimethylaminosilane with silanol, the minimum energy paths as well as the activation and reaction energies are discussed in detail. From minimum energy reaction paths we found that all studied silazanes react exothermically. Bis(dimethylamino)dimethylsilane shows the most exothermic silylation reaction with the lowest activation energies. Therefore, it is a good candidate for the chemical repair of porous films in the semiconductor k-restoring process.     

An evaluation of heuristics for scheduling a non-delay permutation flow shop with family setups to minimize total earliness and tardiness

This paper presents several procedures for developing non-delay schedules for a permutation flow shop with family setups when the objective is to minimize total earliness and tardiness. These procedures consist of heuristics that were found to be effective for minimizing total tardiness in flow shops without family setups, modified to consider family setups and the total earliness and tardiness objective. These procedures are tested on several problem sets with varying conditions. The results show that variable greedy algorithms are effective when solving small problems, but using a genetic algorithm that includes a neighbourhood defined by the sequence of batches of jobs belonging to the same set-up family is effective when solving medium- or large-sized problems. The results also show that if setup times can be reduced a significant reduction in total earliness and tardiness could result.     

Mechanical spectroscopy of decagonal Al–Cu–Fe–Cr quasicrystalline coatings

Mechanical spectroscopy measurements were performed on decagonal quasicrystalline Al–Cu–Fe–Cr coatings of three different thicknesses deposited on a mild steel substrate. The mechanical loss spectra indicate that the internal friction is mostly caused by the quasicrystalline coating and that the contributions of both the steel substrate and the interface are small. The shear modulus measured in torsion increases with temperature, while the Young’s modulus measured in flexion behaves normally. This shear modulus anomaly is interpreted as being due to solid friction between cracked segments of the quasicrystalline coating. This phenomenon also explains the broad athermal maximum found to occur in isochronal internal friction measurements. A quantitative model successfully reproducing the observed behaviour has been developed. Finally, the reversible high-temperature exponential background was interpreted as being due to the onset of the brittle-to-ductile transition in the quasicrystalline coating. The measured activation enthalpy is similar to the value that was deduced from compression tests performed at high temperatures on icosahedral Al–Cu–Fe bulk material.     

Transfer of negative muons from hydrogen to oxygen

Negative muons were trapped in gaseous mixtures of hydrogen and oxygen. The time distributions of the muonic oxygen X-rays showed a clear deviation from a single exponential structure. From these time distributions we evaluated the transfer rate from thermalized muonic hydrogen atoms to oxygen. In order to test the hypothesis of an energy-dependent transfer rate to oxygen we performed Monte Carlo simulations of the thermalization and the transfer process. We report on the present status of our investigations.     

Experimental Search for μd 3He Fusion

The vast majority of muon catalyzed fusion research has been concerned with muonic molecules of hydrogen isotopes only, since the dynamics of higher-Z muonic atoms in general preclude the formation of molecular systems. In the specific case of hydrogen–helium mixtures, bound muonic molecular states can exist, and thus it is possible to search for the reaction μd ³He $$\xrightarrow{{\tilde \lambda f}}$$ μ+α(3.66 MeV)+p(14.64 MeV). Until recently, the theoretical predictions for the nuclear fusion rate in the μd ³He molecule, ${\tilde \lambda }$ _f , ranged over one order of magnitude, from 10⁵ to 10⁶ per second. An experimental upper limit has been measured for ${\tilde \lambda }$ _f in HD + ³He giving a value (<6×10⁴ s^?1 [1]). We report on the analysis of an experiment in D₂ + ³He which has shown a signal coming either from the muon catalyzed reaction, or from the fusion in flight of ³He's formed from dμd fusion.     

The study of prompt and delayed muon induced fission

The mean life times of negative muons bound to actinide nuclei have been measured by detecting the time difference between a stopped muon and the arrival of fragments from delayed fission after muon capture. The deduced capture ratesΛ _c are 1.392(4)·10⁷/s for²³⁷Np, 1.290(7)·10⁷/s for²⁴²Pu and 1.240(7)·10⁷/s for²⁴⁴Pu. The results are compared with published data for the fission and the neutron decay channels and for the electron decay of the bound muon. Including a former measurement ofΛ _c for²³⁹Pu, an isotopic dependence of the muon capture rates in the Pu isotopes is clearly observed.