Search results for "Noble Ga"

Noble gas and CO2 isotopic signatures of the lithospheric mantle underneath Mexico and the Canary Islands: clues from mantle xenoliths and arc lavas

2022

Studying the isotopic composition of fluids trapped in mantle xenoliths opens avenues to understand the origin and cycling of volatiles in the Earth’s upper mantle. In this PhD dissertation, new and in most cases the very first data regarding the isotopic (noble gases and CO2) characterization of the lithospheric mantle portions of three different geodynamic environments are presented: (i) Central and NW Mexico, a continental setting dominated by extension; (ii) the Transmexican Volcanic Belt (TMVB) a subduction setting, and (iii) the Canary Islands, particularly El Hierro and Lanzarote, two oceanic islands formed by mantle plume-derived intraplate volcanism. In total 32 peridotites (includ…

EVIDENCES OF ENRICHED MANTLE (EM-2) SOURCE CONTRIBUTION TO ETNEAN MAGMAS: A COMPREHENSIVE STUDY ON FLUID AND MELT INCLUSIONS OF 2001-2006 ERUPTIONS

2009

A TWO-COMPONENT MANTLE EXTENDING FROM MT ETNA TO HYBLEAN PLATEAU (EASTERN SICILY) AS INFERRED BY AN INTEGRATED APPROACH WITH NOBLE GASES, TRACE ELEME…

2012

Noble gases investigation in fluid inclusions of olivines and pyroxenes from Etnean products erupted in the 2001-2004 period.

2008

Elemental and isotope covariation of noble gases in olivines and pyroxenes from Etnean volcanics erupted during 2001-2005, and genetic relation with …

2009

Mixture and dissolution of laser polarized noble gases: Spectroscopic and imaging applications

2012

MRI of the lungs using hyperpolarized noble gases

2002

The nuclear spin polarization of the noble gas isotopes (3)He and (129)Xe can be increased using optical pumping methods by four to five orders of magnitude. This extraordinary gain in polarization translates directly into a gain in signal strength for MRI. The new technology of hyperpolarized (HP) gas MRI holds enormous potential for enhancing sensitivity and contrast in pulmonary imaging. This review outlines the physics underlying the optical pumping process, imaging strategies coping with the nonequilibrium polarization, and effects of the alveolar microstructure on relaxation and diffusion of the noble gases. It presents recent progress in HP gas MRI and applications ranging from MR mi…

Spinpolarisation langsamer Elektronen durch elastische Streuung an Edelgasatomstrahlen

1968

The angular dependence of spin polarisationP(θ) of electrons elastically scattered by noble gas atomic beams is measured in a double-scattering experiment for electron energies between 40 and 150 eV and over an angular range fromθ=30‡ toθ=150‡. Maximum degree of polarisation measured isP=+ 39.5%±2.6% (Xe; 150eV;θ=60‡). The results are compared with the theoretical values ofCoulthard, which agree approximately with the measurements only for Xenon. For all lower atomic numbers the experimental values are higher than the theoretical ones.

Ageing studies of TPB in noble gas detectors for dark matter and neutrinoless ββ decay searches

2017

Noble gases (Xe, Ar, Kr) are very attractive as detector media in Dark Matter search and neutrinoless double-beta decay experiments. However, the detection of their scintillation light (in the VUV spectral region) requires shifting the VUV light to visible light, where standard photosensors are more efficient. Tetraphenyl butadiene (TPB) is widely used as wavelength shifter, absorbing the VUV light and re-emitting in the blue region (~430nm). TPB is an organic molecule that may degrade due to exposure to environmental agents and also to ultraviolet light. In this work, we present TPB ageing studies due to exposure to VUV light, aiming at quantifying the reduction of the absolute fluorescenc…

On the nature of interactions in the F2 OXe(…) NCCH3 complex: Is there the Xe(IV)N bond?

2016

Nature of the bonding in isolated XeOF2 molecule and F2 OXe(…) NCCH3 complexes have been studied in the gas phase (0 K) using Quantum Chemical Topology methods. The wave functions have been approximated at the MP2 and DFT levels of calculations, using the APFD, B3LYP, M062X, and B2PLYP functionals with the GD3 dispersion correction. The nature of the formal XeO bond in the XeOF2 monomer depends on the basis set used (all-electron vs. the ecp-28 approximation for Xe). Within the all-electron basis set approach the bond is represented by two bonding attractors, Vi = 1,2 (Xe,O), with total population of about 1.06e and highly delocalized electron density in both bonding basins. No bonding bas…