Alkaline Atoms
Mostrando 1-12 de 21 artigos, teses e dissertações.
-
1. Desilication of ZSM-5 and ZSM-12 Zeolites with Different Crystal Sizes: Effect on Acidity and Mesoporous Initiation
In the present work, the desilication of the H-ZSM-5 and H-ZSM-12 zeolites with Si/AL ratios of 28 and 56 and crystal sizes of around 200 and 600 nm, respectively, was performed. Through electron transmission microscopy analysis, it was possible to verify the influence of aluminium gradients on smaller crystals in addition to the exact moment at which the fo
Mat. Res.. Publicado em: 11/02/2019
-
2. Síntese e estudo da atividade eletrocatalítica de óxidos de metais de transição e de nanopartículas de prata e ouro para a reação de redução de oxigênio / Synthesis and study of the electrocatalytic activity of transition metal oxides, and silver and gold nanoparticles for the oxygen reduction reaction
The oxygen reduction reaction (ORR) was studied on electrocatalysts composed by pure and mixed transition metal oxides of Mn, Co, and Ni, including spinel-like structures, and by Ag, Au, and Ag3M/C (M= Au, Pt, Pd e Cu) bimetallic nanoparticles, in alkaline electrolyte. The transition metal oxides were synthesized by thermal decomposition of their nitrates, a
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 10/08/2011
-
3. Espectroscopia de alcalinos em Hélio líquido / Spectroscopy of Alkali in Liquid Helium
Alkali atoms are good probes for the understanding of liquid He properties. As such considerable experimental attention has been devoted to the analysis of the changes of line position and widths of the absorption spectra of alkali atoms in liquid He environment. On the theoretical side, several studies have used simplified models such as bubble and cluster
Publicado em: 2010
-
4. A topologia molecular QTAIM e a descrição mecânico-quântica de ligações de hidrogênio e ligações de di-hidrogênio
Hydrogen bonds formed through the interaction between a high electronic density center (lone electron pairs, π or pseudo-π bonds) and proton donors cause important electronic and vibrational phenomena in many systems. However, it was demonstrated that proton donors interact with hydrides, such as alkali and alkaline earth metals (BeH2, MgH2, LiH and NaH),
Química Nova. Publicado em: 2010
-
5. Estudos da deposição de filmes de diamante CVD sobre carbeto de tungstênio, com interface controlada de boreto / Studies of the deposition of diamond CVD films on tungsten carbide, boride with interface control
The objective of this work was to obtain adherent diamond films on WC-Co substrate through the hot filament assisted CVD technique, using a boriding process to form an intermediate layer and avoid the diffusion of the cobalt to the substrate surface. The boriding process consists of a reactive thermo diffusion treatment, in which boron atoms are spread in th
Publicado em: 2009
-
6. AdsorÃÃo de Ãtomos alcalinos e halogÃnios em uma superfÃcie de Grafeno: um estudo de primeiros princÃpios. / Adsorption of alkaline and alogen atoms on a graphene surface: a frist principle studie
O grafeno à atualmente o tÃpico mais corrente em fÃsica da materia condensada e ciÃncia dos materiais e foi isolado pela primeira vez a menos de quatro anos. O grafeno tem sido proposto como um material alternativo aos nanotubos de carbono em diversas aplicaÃÃes, devido a sua fÃcil sintetizaÃÃo e seu baixo custo. A fim de explorar uma potencial apli
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 11/02/2008
-
7. Determinação isotópica de S (% em átomos de 34S) por espectrometria de massas em amostras de solo, a partir de S-Total e S-Sulfato disponível / Isotopic determination of S (% in atoms of 34S) by mass spectrometry in soil samples based on Total-S and available Sulphate-S
Sulphur in soil may be found under two basic forms; Inorganic-S and Organic-S. Sulphur under inorganic form (Sulphate-S) may be available to plant, however organic sulphur is responsible for 95 % of total sulphur in the most of soils. Aiming quantifies the available sulphur in soil, ammonium acetate plus acetic acid extractor solution was used. Efficiency of
Publicado em: 2007
-
8. Processos binários em átomos de Rydberg / Binary process in Rydberg atoms
This dissertation seeks to address some of the characteristics of collisional processes in ultracold Rydberg atoms. With a Maqneto-Optical Trap (MOT), we trapped a sample of 85Rb, an alkaline metal element, in a region of about lmm at a temperature of a few hundreds of ?K, known in the literature as the "ultracold" regime. The 85Rb atoms are then excited to
Publicado em: 2006
-
9. "Developments of carbn-dispersed electrocatalysts for cathodes of alkaline fuel cells" / "Desenvolvimento de eletrocatalisadores dispersos para o cátodo de células a combustível alcalinas"
The oxygen reduction reaction (ORR) was studied on electrodes formed by Pt monolayers deposited on different metallic substrates, and on carbon-supported electrocatalysts composed by PtM/C (M = V, Cr e Co) and AgPt/C alloys, and on different Mn oxides (Mn3O4/C, Mn2O3/C and MnO2/C) in alkaline electrolyte. The experimentally measured electrocatalytic activiti
Publicado em: 2006
-
10. Intensity dependence for trap loss rate in a magneto-optical trap of strontium
We have measured the collisional loss rate for cold strontium atoms held in a magneto-optical trap as a function of light intensity in the regime of low intensity (2-6 mW/cm²). The results confirm our recently proposed model, where we showed that the sudden increase of loss rate at low intensities does not depend on hyperfine structure changing collision on
Brazilian Journal of Physics. Publicado em: 2004-12
-
11. Calcium magneto-optical trap loaded from a decelerated atomic beam
We describe a new system for laser cooling and trapping of neutral Calcium atoms employing the ¹S0 -¹ P1 resonant transition at 423 nm. An on-axis magneto-optical trap (MOT) is loaded from a Zeeman decelerated atomic beam. When a single laser is used, in order to avoid perturbation of the trap by the deceleration laser beam, this one has been tightly focus
Brazilian Journal of Physics. Publicado em: 2003-06
-
12. Estudo do processo de eliminação de "etch-channels" por eletrodifusão em quartzo sintetico
The sweeping in synthetic quartz is a process of impurity diffusion performed at temperatures of about 500°C with the application of an intense electrical field. The electrodiffusion in synthetic quartz (sweeping), by using for example AG atoms in air, has an increasing technological interest as it makes the material highly resistant to the formation of etc
Publicado em: 1998