Defective h-BN sheet embedded atomic metals as highly active and selective electrocatalysts for NH3 fabrication via NO reduction

The VB-containing defective h-BN sheet is proved to be a feasible support for atomic transition-metal anchoring. In particular, we found the Cu@h-BN and Ni@h-BN are highly active and selective catalysts for NO electro-reduction to generate NH3.

Impact of electron transfer of atomic metals on adjacent graphyne layers on electrochemical water splitting

Moderate electron transfer occurring on atomic metals of catalysts was found to be induced by atomic metals on adjacent graphyne layers and this accelerates electrocatalytic water splitting.

Partículas alfa como projéteis subatômicos: os trabalhos de Hans Geiger

ResumoOs trabalhos para desvendar a estrutura da matéria no começo do século passado fizeram com que vários cientistas elaborassem diferentes experimentos de modo a permitir o entendimento e o arranjo atômico em diferentes metais. Um dos físicos que merece destaque foi Johannes Wilhelm Geiger (1882­1945), também conhecido como Hans Geiger, que desenvolveu uma maneira de estudar a estrutura dos metais utilizando partículas alfa provenientes de compostos de rádio. A técnica consistia em bombardear finas folhas de diferentes metais com partículas alfa e analisar seus desvios. Essa técnica possibilitou que, futuramente, fosse possível a elaboração de outro experimento que constatou, entre outros aspectos, o núcleo atômico. Será́ apresentado, portanto, neste artigo a tradução comentada do artigo On the Scattering of the α–Particles by Matter.Palavras-chave: Partícula alfa; espalhamento de partículas; Hans GeigerAbstractThe work to unravel the structure of matter at the beginning of the last century led several scientists to design different experiments to allow understanding and arrangement atomic metals. One of the prominent physicists was Johannes Wilhelm Geiger (18821945), also known as Hans Geiger, who developed a way to study the structure of metals using alpha particles from radio compounds. The technique consisted of bombarding thin sheets of different metals with alpha particles and analyzing their deviations. This technique made it possible, in the future, to develop another experiment that found, among other aspects, the atomic nucleus. Therefore, it will be presented in this paper how Hans Geiger elaborated his experiments, highlighting their results and difficulties. In addition, the importance of this historical episode in Basic Education will be discussed.Keywords: Alpha particles; scattering particle; Hans Geiger

The observation of chemiluminescent NiO* emissions in the laboratory and in the night airglow

The recent finding of an orange spectral feature in OSIRIS/Odin spectra of the night airglow near 87 km has raised interest in the origin of the emission. The feature was positively identified as the chemiluminescent FeO* emission where the iron is of meteoric origin. Since the meteorite source of atomic metals in the mesosphere contains both iron and nickel, with Ni being typically 6 % of Fe, it is expected that faint emissions involving Ni should also be present in the night airglow. The present study summarizes the laboratory observations of chemiluminescent NiO* emissions and includes a search for the NiO* signature in the night airglow. A very faint previously unidentified "continuum" extending longwave of 440 nm has been detected in the night airglow spectra obtained with two space-borne limb viewing instruments. Through a comparison with laboratory spectra this continuum is identified as arising from the NiO* emission. The altitude profile of the new airglow emission has also been measured. The similarity of the altitude profiles of the FeO* and NiO* emissions also suggests the emission is NiO as both can originate from reaction of the metal atoms with mesospheric ozone. The observed NiO* to FeO* ratio exhibits considerable variability; possible causes of this observed variation are briefly discussed.