関連する実験動画
Updated: Jul 10, 2026
10:35
Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
[Fe (II) (bpy) (III) ] (II+) の溶液中の超高速な非アディアバティックダイナミクス
Wojciech Gawelda1, Andrea Cannizzo, Van-Thai Pham
1Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, Faculté des Sciences de Base, ISIC-BSP, Lausanne, Switzerland.
Journal of the American Chemical Society
|June 15, 2007
まとめ
鉄 (II) - トリス (二ピリジン) の超高速リラクゼーションは,シングレット状態からトリプレート状態への急速なインターシステムクロス (ISC) 経由で発生し,その後にクインテット状態の集団が続きます. このプロセスは,金属のスピン-軌道結合とは独立しています.
科学分野:
- フォトケミストリー フォトケミストリー
- 超高速スペクトル顕微鏡
- 協調化化学について
背景:
- 鉄 (II) -トリス (ビピリジン) のような鉄 (II) 複合体は,光化学において極めて重要です.
- 興奮状態のダイナミクスを理解することは,新しい光活性材料の設計の鍵です.
- 超高速プロセスは,光化学反応の初期段階を支配する.
研究 の 目的:
- 刺激後の水性鉄 (II) -トリス (二ピリジン) の超高速のリラックス経路を特徴づける.
- システム間交差 (ISC) とその後の緩和の時間スケールを決定する.
- リラクゼーションダイナミクスにおけるスピン・軌道相互作用の役割を調査する.
主な方法:
- フェムト秒の光向上変換スペクトロスコーピー.
- フェムトセカンド一時吸収 (TA) スペクトロスコーピー.
- 単数値分解とTAデータの総合分析.
主要な成果:
- 非常に短命なシングレット金属からリガンドへの電荷移転 (1MLCT) 放射 (<20 fs) が観察されました.
- 三重金属からリガンドへの電荷伝送状態 (3MLCT) へのシステム間交差 (ISC) が特徴付けられました (<150 fs).
- 3つの異なる時間スケール (120 fs, 960 fs, 665 ps) が特定され,3MLCTの衰退,クインテット状態の集団,そして衰退に対応しました.
結論:
- 高いISC率は金属の回転軌道定数とは無関係であり,回避された交差点を伴うメカニズムを示唆しています.
- シングレットとトリプルレット潜在エネルギー曲線の間の回避された交差のモデルが,観測されたISC率を説明します.
- エネルギー分散は急速に (2000 cm-1/100 fs) 発生し,フェルミの黄金律と一致しています.
関連する概念動画
02:55Exceptions to the Octet Rule
Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:30Ladder Diagrams: Redox Equilibria
Ladder diagrams are useful tools for understanding redox equilibrium reactions, especially the effects of concentration changes on the electrochemical potential of the reaction. The vertical axis in the redox ladder diagrams represents the electrochemical potential, E. The area of predominance is demarcated using the Nernst equation.
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
01:27Fast Reactions
Fast reactions occurring in times shorter than the time needed to mix reactants pose a unique challenge for investigation. In a liquid-phase continuous-flow system, reactants A and B are swiftly pushed into the mixing chamber, where mixing occurs within 1 ms. The reaction mixture then flows through an observation tube, and one measures light absorption to determine species concentrations at various points of the tube. This method is most appropriate when relatively large volumes of reactants...