Alkali Atoms
Mostrando 1-10 de 10 artigos, teses e dissertações.
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1. 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
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2. 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
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3. 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
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4. Poli(oxido de etileno-co-epicloridrina) : degradação foto-oxidativa e termica, e blenda com polipropileno
Polymers derived from ethylene oxide and epichlorohydrin, like poly(epichlorohydrin-co-ethylene oxide) elastomer, are studied as polymer electrolyte for application in photo-electrochemical devices. These materiaIs present the ability to form complexes with alkali salts, presenting high ionic conductivity. In these devices the conversion of the solar energy
Publicado em: 2003
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5. Espectroscopia Ãptica nÃo linear em sistemas atÃmicos envolvendo nÃveis de Rydberg
In this thesis we study nonlinear optical effects in alkali vapors, in which Rydberg levels play the role of near resonant intermediate levels, focusing our attention in processes such as: four wave mixing (FWM), two photon absorption, sum frequency generation (SF) and difference frequency generation (DF). We analyze a FWM process with two-photon transitions
Publicado em: 2002
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6. Energy transfer from PO excited states to alkali metal atoms in the phosphorus chemiluminescence flame
Phosphorus chemiluminescence under ambient conditions of a phosphorus oxidation flame is found to offer an efficient electronic energy transferring system to alkali metal atoms. The lowest resonance lines, 2P3 / 2,½→2S½, of potassium and sodium are excited by energy transfer when an argon stream at 80°C carrying potassium or sodium atoms intersects a ph
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7. Synthesis of the diastereomers of thymidine glycol, determination of concentrations and rates of interconversion of their cis-trans epimers at equilibrium and demonstration of differential alkali lability within DNA.
5,6-dihydroxy-5,6-dihydrothymidine (thymidine glycol) is a major product of the reaction of thymidine with reactive oxygen species, including those generated by ionizing radiation. Thymidine glycol exists as 2 diastereomeric pairs by virtue of the chirality of the C(5) and C(6) atoms. A simple procedure is described for synthesizing and purifying each of the
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8. Arizona porphyry copper/hydrothermal deposits II: Crystal structure of ajoite, (K + Na)3Cu20Al3Si29O76(OH)16⋅∼8H2O
A crystal from the type locality Ajo, AZ, yielded just enough intensity from streaked diffractions using synchrotron x-rays at the Advanced Photon Source to solve the crystal structure with composition (K + Na)3Cu20Al3Si29O76(OH)16⋅∼8H2O; triclinic, P1̄, a = 13.634(5) Å, b = 13.687(7), c = 14.522(7), α = 110.83(1)°, β = 107.21(1), γ = 105.68(1); r
National Academy of Sciences.
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9. Modulation of neocarzinostatin-mediated DNA double strand damage by activating thiol: deuterium isotope effects.
The neocarzinostatin chromophore causes double-strand damage at AGC sequences on DNA by concomitant 1'-oxidation at C and 5'-oxidation at the T on the complementary strand. The extent of this damage is dependent upon the structure of the thiol used for activation. Deuterium isotope effects suggest that this dependence on thiol structure may be due to interna
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10. Functional nucleotide excision repair is required for the preferential removal of N-ethylpurines from the transcribed strand of the dihydrofolate reductase gene of Chinese hamster ovary cells.
Transcription-coupled repair of DNA adducts is an essential factor that must be considered when one is elucidating biological endpoints resulting from exposure to genotoxic agents. Alkylating agents comprise one group of chemical compounds which modify DNA by reacting with oxygen and nitrogen atoms in the bases of the double helix. To discern the role of tra