Thermal properties of smoky quartz at very low temperatures

The existence of a distribution of low-lying energy levels associated with holes trapped at substitutional aluminium impurities is confirmed by measurements of low temperature specific heat and dielectric loss. A large linearly temperature-dependent contribution to the specific heat is observed at temperatures below 1 K, down to 30 mK. A localization temperature describing the width of the distribution of the energy levels is estimated to vary between 3 and 6 K.

We determined the thermal conductivity down to 30 mK and attribute the decrease below the boundary-scattering value to irradiation damage generally, arguing that it is not attributable to resonant scattering.     

Isomer stability and bond-breaking energies of N8C8H8 cages

Molecules consisting entirely or predominantly of nitrogen have been extensively investigated for their potential as high-energy density materials (HEDM). Such molecules react to produce N2 and large amounts of energy, but many such molecules are too unstable for practical applications. In the present study, cage isomers of N8C8H8 are studied using theoretical calculations to determine the structural features that lead to the most stable cages and determine the energetics of dissociation for the various isomers. The isomers are evaluated for thermodynamic (isomer vs isomer) stability and kinetic (with respect to dissociation) stability. Density functional theory (B3LYP), perturbation theory (MP2), and coupled-cluster theory [CCSD(T)] are employed, in conjunction with the cc-pVDZ basis set of Dunning. Trends in isomer stability and dissociation energies are calculated and discussed.     

Manipulating biphotonic qutrits

Quantum information carriers with higher dimension than the canonical qubit offer significant advantages. However, manipulating such systems is extremely difficult. We show how measurement-induced nonlinearities can dramatically extend the range of possible transforms on biphotonic qutrits-three-level quantum systems formed by the polarization of two photons in the same spatiotemporal mode. We fully characterize the biphoton-photon entanglement that underpins our technique, thereby realizing the first instance of qubit-qutrit entanglement. We discuss an extension of our technique to generate qutrit-qutrit entanglement and to manipulate any bosonic encoding of quantum information.     

Geometrical structures,bending potentials,and vibrational frequencies ν1 for 1A″ states of HSiBr,HSiCl, and DSiCl

The geometrical structures and the approximate bending potentials are determined for excited electronic states ¹A″ in HSiBr, and in HSiCl and DSiCl. A Hamiltonian for large amplitude bending vibration and K type rotation contains parameters which were adjusted to yield energy levels consistent with data observed spectroscopically. The effect of centrifugal stretching of the HSi bond was treated by a simple semiclassical method. In the process of applying this method it was found that the HSi stretching frequencies ν₁ do not have the values recommended by Herzberg and Verma, but have the alternate values given by these authors. The barriers to the linear conformation were found to be approximately 8700 cm^?1 for HSiBr, and 12 400 cm^?1 for HSiCl and DSiCl.     

Hydrogen absorption in LaNi4.9Fe0.1

The magnetic properties of LaNi_4.9Fe_0.1 and its hydride have been studied by making Mössbauer and magnetic susceptibility measurements. ⁵⁷Fe Mössbauer spectroscopy shows a small increase in the isomer shift after hydriding. An increase in the magnetic susceptibility after hydriding was observed.     

Low temperature dielectric relaxation spectroscopy

It has been found during the last 2$\text{1}\text{2}$ years that dielectric relaxations associated with many organic compounds could be observed by dissolving or dispersing them in hydrocarbon solvents or matrices and cooling them to 4.2 K. Such relaxations were nearly always attributable to conformational changes of independent solute or dopant molecules and could be used as a means of spectroscopic investigation. Two ways of using such data are outlined and the advantages and limitations are discussed using ROH, RSH and R₁R₂NH compounds as examples.     

Proof of Concept Coded Aperture Miniature Mass Spectrometer Using a Cycloidal Sector Mass Analyzer,a Carbon Nanotube (CNT) Field Emission Electron Ionization Source,and an Array Detector

Despite many potential applications, miniature mass spectrometers have had limited adoption in the field due to the tradeoff between throughput and resolution that limits their performance relative to laboratory instruments. Recently, a solution to this tradeoff has been demonstrated by using spatially coded apertures in magnetic sector mass spectrometers, enabling throughput and signal-to-background improvements of greater than an order of magnitude with no loss of resolution. This paper describes a proof of concept demonstration of a cycloidal coded aperture miniature mass spectrometer (C-CAMMS) demonstrating use of spatially coded apertures in a cycloidal sector mass analyzer for the first time. C-CAMMS also incorporates a miniature carbon nanotube (CNT) field emission electron ionization source and a capacitive transimpedance amplifier (CTIA) ion array detector. Results confirm the cycloidal mass analyzer’s compatibility with aperture coding. A >10× increase in throughput was achieved without loss of resolution compared with a single slit instrument. Several areas where additional improvement can be realized are identified.

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