Composition analysis of single semiconductor nanowires using pulsed-laser atom probe tomography

We report the composition analysis of single InAs and Si semiconductor nanowires using pulsed-laser atom probe tomography. The experimental conditions and sample geometries needed to realize 3-D composition mapping are described in detail. InAs mass spectra obtained using voltage pulses and laser pulses are compared, and are found to be superior for pulsed-laser evaporation. The ability to analyze intrinsic Si nanowires using pulsed laser evaporation is demonstrated. No peaks associated with the gold catalyst used were found in the InAs or the Si nanowire mass spectra. PACS 68.70.+w; 61.82.Fk; 61.72.Ss     

Thallium chalcohalides for X-ray and γ-ray detection

We report that the chalcohalide compound Tl(6)SeI(4) is a promising material for efficient X-ray and γ-ray detection. This material has a higher figure of merit than the current state-of-the-art material for room-temperature operation, Cd(0.9)Zn(0.1)Te (CZT). We have synthesized high-quality single-crystalline wafers of Tl(6)SeI(4) with detector-grade resistivities and good carrier transport of both electrons and holes. We demonstrate that pulse height spectra recorded using Co-57 radiation show an energy resolution matching that of a commercial CZT detector material.     

High power single frequency solid state master oscillator power amplifier for gravitational wave detection

High power single frequency, single mode, linearly polarized laser output at the 1 μm regime is in demand for the interferometric gravitational wave detectors (GWDs). A robust single frequency solid state master oscillator power amplifier (MOPA) is a promising candidate for such applications. We present a single frequency solid state multistage MOPA system delivering 177 W of linearly polarized output power at 1 μm with 83.5% TEM(00) mode content.     

Multi-item lot size determination and scheduling under capacity constraints

This paper deals with the planning of a production group, which has to produce several products. For each product there is a delivery plan covering several periods. Moreover, there are capacity constraints. Such a situation requires integrated optimization of lot sizes and lot scheduling. Since exact solution of the problem is in general not feasible, we will present a non exact approach which gives quite good results in some practical cases and might be a good starting point in other cases.     

Carbon-13?proton coupling constants in N-substituted imidazoles. A 13C NMR study and MO calculations

The ¹³C NMR data of imidazole, and N-methyl-, N-acetyl-, N-trifluoroacetyl-, N-heptafluorobutyryl- and 2-methyl-imidazoles, were obtained from proton-noise decoupled and single frequency NOE ¹³C NMR spectra. The considerable changes in the directly-bonded (C, H) coupling constants upon N-acetylation of the imidazole ring, which are comparable to those noted when going from the neutral to the cationic form of imidazole, are primarily due to the large π-electron transfer ability of the N-acetyl- and N-trifluoroacetyl-substituents. The differences in magnitude of the three-bond (C, H) coupling constants along different paths in the imidazole ring may be attributed to the larger π-contributions across a pyridine-like nitrogen than along a pyrrole-like nitrogen.     

Cage compounds IV. 1H and 13C NMR study of 3,6-epoxypentacyclo-[6.2.2.02,7.04,10.05,9]dodecane and 3,6-epoxypentacyclo-[6.2.1.02,7.04,10.05,9]undecane

The complete ¹H and ¹³C NMR assignments for 3,6-epoxypentacyclo[6.2.2.0^2,7.0^4,10.0^5,9]dodecane and 3,6-epoxypentacyclo[6.2.1.0^2,7.0^4,10.0^5,9]undecane are reported. The difference between the ¹H and ¹³C chemical shifts and one-bond proton-carbon coupling constants of these two compounds are adequately explained by the difference in the hybridization of the C? H bonds.     

Markov decision processes and strongly excessive functions

Strongly excessive functions play an important role in the theory of Markov decision processes and Markov games. In this paper the following question is investigated: What are the properties of Markov decision processes which possess a strongly excessive function? A probabilistic characterization is presented in the form of a random drift through a partitioned state space. For strongly excessive functions which have a positive lower bound a characterization is given in terms of the lifetime distribution of the process.Finally we give a characterization in terms of the spectral radius.     

Assignment and sign determination of (C,H) and (H,H) coupling constants in N-acetylimidazole with selective population inversion experiments

The assignment of the (C, H) couplings in N-acetylimidazole and the determination of the relative signs of all (C, H) and (H, H) couplings with SPI experiments are described. All coupling constants are of the same, positive, sign as the directly-bonded (C, H) coupling constants. Some advantageous features of the SPI technique, such as selectivity and increased sensitivity, are discussed in comparison to conventional double irradiation methods.     

SINGLET OXYGEN LUMINESCENCE SPECTRA: A COMPARISON OF INTERFEROMETER- AND GRATING-BASED SPECTROMETERS

Abstract— The current trend in methodology for determining IR and near-IR absorption spectra is to employ interferometer-based instruments to replace the monochromator-based devices used heretofore. As a dispersion element, the interferometer offers major improvements in spectral resolution (Connes advantage), light throughput (Jacquinot advantage) and data acquisition through multiplexing (Felgett advantage). We have compared signal-to-noise (S/N) ratios of grating-based and interferometer-based instruments for making spectral determinations of near-IR luminescence. Our results show that under identical excitation and detector conditions the interferometer instrument easily outperforms the grating, giving a 10-fold improvement in S/N at high signal amplitude (A_488nm= 0.97) and a 20-fold improvement when the signal amplitude is low (A_488nm= 0.06). Although some spectral resolution is sacrificed when scan times on the Fourier transform (FT)IR are significantly shortened, the S/N ratio was found only to decrease by a factor of 2 for a 10-fold decrease in scan time. This adds to the advantages of the FT1R technique because the S/N will thus improve for the same total acquisition time.