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Hyperpolarized Xenon for NMR and MRI Applications
Published on: September 6, 2012
ネオンの同位体は,地球マントルのコンベクションと揮発性起源を制約する
Chris J Ballentine1, Bernard Marty, Barbara Sherwood Lollar
1Department of Earth Sciences, University of Manchester, Oxford Road, Manchester M13 9LP, UK. chris.ballentine@manchester.ac.uk
Nature
|January 7, 2005
まとめ
地球の原始的な揮発性物質は,初期の太陽星雲ではなく,蓄積する物質の太陽放射線から発生した可能性が高い. マントルガスのネオン同位体は,この重要な違いを明らかにし,揮発性起源の以前のモデルに挑戦しています.
科学分野:
- 地質化学 地質化学
- 惑星科学は惑星科学である.
- 同位体地質学とは,同位体地質学である.
背景:
- 地球の原始的な揮発性物質の起源を理解することは,太陽星雲と遅い蓄積モデルを区別するための鍵です.
- ネオンの同位体は,地球のマントルの揮発性源の重要なトレーサとして機能する.
研究 の 目的:
- 地球のコンベクトマントルの原始的な揮発性物質の起源を調査する.
- 初期の地球への揮発性物質の配送の競合するモデルをテストするために.
主な方法:
- マグマ質の二酸化炭素 (CO2) 井戸ガスにおけるネオン同位体の分析.
- 同位体シグネチャーを太陽星雲や後期増積物質源と比較.
主要な成果:
- コンベクトマントルのネオンイソトープは,蓄積する物質の太陽体球放射線からの源と一致する.
- 観測されたネオン同位体の異質性は,マントルの異なる源を示唆し,羽根が支配する揮発性供給のモデルに挑戦しています.
- 高貴ガス濃度は,深層マントルの揮発性流動の必要性を軽減する可能性があります.
結論:
- 地球のコンベクトマントルの原始的な揮発性物質の主要な源は,初期の太陽星雲ではなく,遅い時期の蓄積物質である可能性が高い.
- ネオンとヘリウムの同位体シグネチャーは,支配的な揮発性輸送メカニズムとして遅い蓄積を指しています.
- マントルの揮発性物質の在庫に関する既存のモデルは,同位体証拠に基づいて改訂する必要があります.
関連する概念動画
The Bohr Model
Following the work of Ernest Rutherford and his colleagues in the early twentieth century, the picture of atoms consisting of tiny dense nuclei surrounded by lighter and even tinier electrons continually moving about the nucleus was well established. This picture was called the planetary model since it pictured the atom as a miniature “solar system” with the electrons orbiting the nucleus like planets orbiting the sun. The simplest atom is hydrogen, consisting of a single proton as the nucleus...
The Energies of Atomic Orbitals
In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are also observed. The attractive and repulsive forces are dependent on the distance between the particles, as well as the sign and magnitude of the charges on the individual particles. When the charges on the particles are opposite, they attract each other. If both particles have the same charge, they repel each other.
Types of Radioactivity
The most common types of radioactivity are α decay, β decay, γ decay, neutron emission, and electron capture.
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
Nuclear Overhauser Enhancement (NOE)
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...

