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Flame Photometry: Overview01:02

Flame Photometry: Overview

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Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...
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Flame Photometry: Lab01:16

Flame Photometry: Lab

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In a flame photometer, when a solution like potassium chloride is aspirated into the flame, the solvent evaporates, leaving behind dehydrated salt. This salt dissociates into free gaseous atoms in their ground state. Some of these atoms absorb energy from the flame, leading to their excitation. The excited atoms return to the ground state, emitting photons at characteristic wavelengths. Because only electronic transitions are involved, the resulting emission lines are very narrow. The intensity...
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Emission Spectra02:39

Emission Spectra

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When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
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Nuclear Fusion02:45

Nuclear Fusion

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The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
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Fermi Level Dynamics01:12

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The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
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Fermi Level01:18

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The Fermi-Dirac function is represented by an S-shaped curve indicating the probability of an energy state being occupied by an electron at a given temperature. The Fermi level is the energy level at which there is a fifty percent chance of finding an electron, and it is positioned between the lower-energy valence band and the higher-energy conduction band.
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
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Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface
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太陽型恒星のスーパーフレアについて

Hiroyuki Maehara1, Takuya Shibayama, Shota Notsu

  • 1Kwasan and Hida Observatories, Kyoto University, 17 Ohmine-cho Kita Kazan, Yamashina-ku, Kyoto City, Kyoto 607-8471, Japan. maehara@kwasan.kyoto-u.ac.jp

Nature
|May 25, 2012
PubMed
まとめ

スーパーフレア,強力な恒星爆発は,より大きな星斑を持つ太陽型恒星を含む365の恒星で観測されました. これらの現象は,急速に回転する星ではより頻繁に起こりますが,ホットジュピターと直接関連していません.

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科学分野:

  • * 天体物理学
  • * 恒星物理学について
  • * エクソプラネット科学

背景:

  • *太陽フレアは,太陽斑の近くに磁気エネルギーの突然の放出から発生します.
  • * 太陽のフレアよりもはるかにエネルギーが強いスーパーフレアは,急速に回転する恒星や太陽型恒星を含む様々な恒星で観測されています.
  • * 太陽型恒星におけるスーパーフレアの以前の研究は,その希少性のために限られていた.

研究 の 目的:

  • * 太陽型恒星を含む恒星の大量のサンプルで,スーパーフレアの特徴と頻度を調査する.
  • *スーパーフレア,恒星の回転,星斑の大きさ,そして熱い木星系外惑星の潜在的影響の関係を探求する.
  • * 約8万3000の恒星で120日間にわたって観測された365のスーパーフレアを分析するために.

主な方法:

  • *120日間で約8万3000個の恒星をフォトメトリック観測した.
  • *365のスーパーフレアイベントの特定と分析.
  • * 恒星斑の大きさを推論するために準周期的な輝度調節を調べた.
  • *フレアエネルギー,恒星回転周期,系外惑星の存在との相関分析.

主要な成果:

  • * ゆっくり回転する太陽型星からのイベントを含む365のスーパーフレアが観測されました.
  • * 超フレアを発した太陽型の恒星は,太陽よりもはるかに大きな星斑の証拠を示した.
  • *スーパーフレアの最大エネルギーは恒星の回転周期と相関していませんが,高速回転する恒星では周波数が高くなります.
  • * 超燃焼を観測した太陽型恒星の周りにホットジュピター系外惑星は検出されなかった.

結論:

  • *スーパーフレアは,様々な恒星で観測される現象で,その特徴は,自転や星斑の大きさなどの恒星の特性によって影響を受けます.
  • * 恒星の急速な回転は,必ずしも最大エネルギーではないが,超フレアの頻度を増加させるように見える.
  • * 熱い木星が検出されていないことから,太陽型の恒星における超大火の発生に希少な貢献者が存在することを示唆し,以前の仮説に異議を唱える.