On the origin of emission and thermal quenching of SRSO:Er3+ films grown by ECR-PECVD

Silicon nanocrystals embedded in a silicon-rich silicon oxide matrix doped with Er³⁺ ions have been fabricated by electron cyclotron resonance plasma-enhanced chemical vapor deposition. Indirect excitation of erbium photoluminescence via silicon nanocrystals has been investigated. Temperature quenching of the photoluminescence originating from the silicon nanocrystals and the erbium ions has been observed. Activation energies of the thermally activated quenching process were estimated for different excitation wavelengths. The temperature quenching mechanism of the emission is discussed. Also, the origin of visible emission and kinetic properties of Er-related emission have been discussed in details.     

Über Nachbeschleunigung bei Braunschen Röhren

Zusammenfassung Man darf für eine genauere Beurteilung der Nachbeschleunigung das Nachbeschleunigungsfeld nicht durch eine elektrische Doppelschicht ersetzen. Man muß vielmehr der Verteilung des axialsymmetrischen Verlaufs des Beschleunigungsfeldes voll Rechnung tragen und die auftretenden Radialkräfte berücksichtigen. In diesem Falle ergibt sich als besonderes Ergebnis, daß bei genügend hoher Beschleunigungsspannung die Empfindlichkeit einer Braunschen Röhre mit der Beschleunigungsspannung zunimmt, wobei sich gleichzeitig die Ablenkungsrichtung umkehrt. Es kann sogar die normale Empfindlichkeit ohne Beschleunigungsspannung erreicht, und unter Umständen übertroffen werden. Da der Versuch die Richtigkeit dieser Aussage ergibt, so ist anzunehmen, daß sich das neue Ergebnis auf den Bau von empfindlichen Kathodenstrahloszillographen günstig auswirken wird.     

Discrete uniform mixtures via posterior means

In this paper, we are concerned with identification of a discrete uniform mixture by the posterior mean. An exact formula for a prior distribution is given. Also some examples featuring negative binomial, negative hypergeometric and beta-Pascal distributions are provided.     

Tests of Pore-Size Distributions Deduced from Inversion of Simulated and Real Adsorption Data

An adsorption isotherm provides indirect information about the geometry of the host material and its interaction with the adsorbed fluid. This paper presents a critical study of the “inversion” of experimental data to elucidate desired information about this geometry. Using Ar and H₂ as representative classical and quantum fluids and a carbon slit-pore geometry, we compare the accuracy of isotherms derived from non-local density functional theory with isotherms from grand canonical Monte Carlo simulations, using a quantum-corrected potential for H₂. We determine the pore size distributions (PSDs) for a series of model and experimental materials by inverting the adsorption integral equation, with the goal of probing the ability of the inversion procedure to reproduce faithfully the input pore size distribution and ascertain the reality of anomalous gaps often deduced in the literature. Drawing from the GCMC simulations, we then explore the concept of effective porous materials, or ‘iso-PSDs’, which have similar adsorption isotherms, despite very different pore size distributions.     

Carbon Monoxide and Nitric Oxide as Examples of the Youngest Class of Transmitters

The year 2021 is the 100th anniversary of the confirmation of the neurotransmission phenomenon by Otto Loewi. Over the course of the hundred years, about 100 neurotransmitters belonging to many chemical groups have been discovered. In order to celebrate the 100th anniversary of the confirmation of neurotransmitters, we present an overview of the first two endogenous gaseous transmitters i.e., nitric oxide, and carbon monoxide, which are often termed as gasotransmitters.     

Porosity of polymer materials by various techniques

The porosity of porous copolymer 1-vinyl-2-pyrrolidone-divinylbenzene has been studied by nitrogen adsorption, temperature programmed desorption, and positronium annihilation lifetime spectroscopy. It was shown that the pore structure characteristics depends on the swelling of the polymer material in various solvents. The structural features of polymeric materials restructured under different conditions are described and the structural changes are discussed. The applicability of PALS technique in structural investigations is presented.     

Detailed mass size distributions of atmospheric aerosol species in the Negev desert, Israel, during ARACHNE-96

As part of the 1996 summer intensive of the Aerosol, RAdiation and CHemistry Experiment (ARACHNE-96), the mass size distribution of various airborne particulate elements was studied at a remote site in the Negev Desert, Israel. Aerosol collections were made with 8-stage PIXE International cascade impactors (PCIs) and 12-stage small deposit area low pressure impactors (SDIs) and the samples were analyzed by PIXE for about 20 elements. The mineral elements (Al, Si, Ca, Ti, Fe) exhibited a unimodal size distribution which peaked at about 6 μm, but the contribution of particles larger than 10 μm was clearly more pronounced during the day than during night. Sulphur and Br had a tendency to exhibit two modes in the submicrometer size range, with diameters at about 0.3 and 0.6 μm, respectively. The elements V and Ni, which are indicators of residual fuel burning, showed essentially one fine mode (at 0.3 μm) in addition to a coarse mode which represented the mineral dust contribution. Overall, good agreement was observed between the mass size distributions from the PCI and SDI devices. The PCI was superior to the SDI for studying the size distribution in the coarse size range, but the SDI was clearly superior for unravelling the various modes in the submicrometer size range.