関連する実験動画
Updated: Jun 21, 2026

06:42
Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
液体の水の回転運動はアニソトロピックである:核磁気共鳴と分子動力学のシミュレーション研究
J Ropp1, C Lawrence, T C Farrar
1Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|August 17, 2001
まとめ
実験的なNMRは,液体の水中のアニゾトロプ的回転運動を明らかにします. デウテリウムと酸素-17のリラックス時間は,温度によって異なる分子の方向転換のダイナミクスを示している.
科学分野:
- 物理化学 物理化学
- 化学物理 化学物理
- スペクトル顕微鏡検査です.
背景:
- 核磁共振 (NMR) スペクトロスコピーは,分子ダイナミクスを探査するための強力なツールです.
- 化学的および生物学的プロセスにおける水の至る所に存在する役割のために,水の回転ダイナミクスを理解することは極めて重要です.
- 以前の研究では,水の構造と動力学に関する洞察が提供されましたが,正確な回転相関時間は,依然として研究の活発な分野です.
研究 の 目的:
- NMRリラクゼーション測定を用いて,水分子の回転相関時間を実験的に決定する.
- 水の回転ダイナミクスの温度依存性を調査するために.
- 水の回転運動のアニソトロピーを評価するために.
主な方法:
- デュテリウム (T1) と酸素-17 (T1) のリラクゼーション時間をデュテリウム濃縮液体水で測定した実験的な核磁気共振 (NMR) 測定.
- 四極結合定数と非対称性パラメータの決定は,水群の初期計算と実験的な化学変化測定から得られた.
- リラクゼーションデータを分析して,回転相関時間を抽出する.
主要な成果:
- D2 ((16) OにおけるOD結合ベクトルの回転相関時間は, 275 K の 5.8 ps から 350 K の 0.86 ps に減少した.
- D2(16) Oの薄型D2(17) Oの平面外ベクトルの回転相関時間は, 275Kでの4.4psから350Kでの0.64psに減少しました.
- 実験結果は,水分子のアニゾトロプ的回転運動を示しています.
結論:
- この研究は,液体の水におけるアニゾトロプ的回転ダイナミクスの実験的証拠を提供する.
- NMRのリラクゼーション測定は,分子方向転換を特徴付けるための信頼できる方法を提供します.
- 低温での実験データと分子動力学シミュレーションの間の不一致は,シミュレーションモデルの精錬を要する領域を強調しています.
関連する概念動画
Fluid Mosaic Model
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.LipidsThe most...
Fluid Mosaic Model
Scientists identified the plasma membrane in the 1890s and its principal chemical components (lipids and proteins) by 1915. The model for plasma membrane structure, proposed in 1935 by Hugh Davson and James Danielli, was the first model to be widely accepted in the scientific community. The model was based on the plasma membrane's "railroad track" appearance in early electron micrographs. Davson and Danielli theorized that the plasma membrane's structure resembled a sandwich with the analogy of...
Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
Atomic Nuclei: Types of Nuclear Relaxation
Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...

