アストロ物理学的氷の中で,冷凍温度でフォーマルデヒドと有機分子の生成
W A Schutte1, L J Allamandola, S A Sandford
1NASA/Ames Research Center, Moffett Field, CA 94035, USA.
まとめ
アンモニア (NH3) は,氷の環境におけるホルムアルデヒド (H2CO) 反応に不可欠であり,複雑な有機分子を形成します. これらの熱反応は40〜80Kの間に発生し,彗星と恒星間化学を理解する上で重要な役割を果たしています.
科学分野:
- アストロケミストリー アストロケミストリー
- 化学動力学 化学動力学
- 惑星科学は惑星科学である.
背景:
- フォーマルアルデヒド (H2CO) は,恒星間および彗星の氷の重要な分子です.
- 複雑な有機分子の形成経路を理解することは,天体生物学にとって不可欠です.
- 凍結氷の化学反応は,天体の構成において重要な役割を果たします.
研究 の 目的:
- 凍結氷における熱的に促進されたホルムアルデヒド反応の役割を調査する.
- フォーマルデヒド反応に対するアンモニア (NH3) の影響を決定する.
- これらの反応の産物とその影響が彗星と星間化学に及ぼす影響を特定する.
主な方法:
- 赤外線光譜を用いて,H2CO,H2O,CH3OH,CO,NH3を含む氷を研究した.
- 反応は冷凍氷マトリックスで研究された.
- 反応産物と発症温度を特定するために,スペクトル分析を行った.
主要な成果:
- 少量のNH3 (NH3/H2CO >= 0.005) は,H2COを複雑な有機物 (> 40%) に大きく変換する.
- H2CO反応はNH3の存在を必要とし,40〜80Kの間から始まる.
- 5つの異なる製品,主にポリオキシメチレン誘導体が形成され,放射線製品と異なる.
結論:
- NH3によって触媒化された熱的H2CO反応は,彗星や恒星間氷の複雑な有機物質の有効な源である.
- 製品の分布は,最初の氷の組成に敏感であり,彗星の歴史のトレーサとして機能します.
- 彗星p/ハレー彗星の有機物質のおよそ3%は,これらの熱反応から発生している可能性があります.
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