Development and Application of NMR Signal Enhancement Technique by using Laser-Excited Triplet State

激光激发三重态核磁共振信号增强技术的开发与应用

• 批准号: 11440175
• 负责人: TAKEGOSHI Kiyonori
• 金额: $ 8万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440175/
• 关键词: solid NMR; photo-excited triplet state; laser; dynamic nuclear polarization; polarization transfer; pentacene; naphthalene; 光励起三重項状態; NMR

In NMR, the low frequency leads to low sensitivity. This is the biggest remaining problem of NMR.We are investigating a possibility of improving the sensitivity using dynamic nuclear polarization (DNP). We transfer the big polarization of electron spins in a photo-excited triplet state to nuclear spins by cross polarization. Comparing with DNP by paramagnetic species, this approach has a potential for obtaining much larger polarization.Firstly, we exmained 13.6 MHz proton NMR for a single crystal (18 mg) of perdeuterated naphthalene (the residual proton content is 0.8%) doped with 0.015 mo1% pentacene. The pentacene molecules in the naphthalene lattice are photo-excited to the triplet state, from which the electron polarization is trabsfered to the ^1H spins. We could achieve the polarization up to 67.5% by DNP, which is essentially the same with the electron polarization of about 63%. Thus, the theoretically maximum proton polarization has been attained for the first time. The proton … More polarization is 3.4×10^5 times as large as the thermal equilibrium value. The buildup time constant is 420 s, being much shorter than that (7430 s) in normal naphthalene.Secondly, to examine the applicability of this approach for a powdered sample, we undertook a similar expariment for a powdered naphthalene sample doped with pentacene. For perdeuterated naphthalene, the proton polarization reaches to 10000 times as large as the thermal equilibrium value at 100 K.For non-deuterated naphthalene, the gain is ca. 3000 at 100 K.These result show that this approach may be hopeful to obtain high NMR sensitivity in interesting systems by applying the DNP technique to interesting guest/host systems or by transferring the big polarization created in such a system as pentacene-doped naphthalene to initially unpolarized interesting systems via the surfaces. As an interesting example of applications, the present DNP technique may be used to greatly improve the NMR sensitivity of a system used for NMR quantum computing and to initialize the computer. Less

在NMR中，低频率导致低灵敏度。这是NMR的最大问题。我们正在研究使用动态核极化（DNP）提高灵敏度的可能性。我们利用交叉极化将光激发三重态电子自旋的大极化转移到核自旋上。首先，我们用13.6MHz质子核磁共振谱研究了18 mg全氘代萘（剩余质子含量为0.8%）掺0.015mol ~（-1）%并五苯的单晶。萘晶格中的并五苯分子被光激发到三重态，电子极化从三重态转移到^1H自旋。通过DNP，我们可以实现高达67.5%的极化，这与电子极化约63%基本相同。因此，理论上的最大质子极化已首次获得。质子 ...更多信息 极化是热平衡值的3.4×10^5倍。建立时间常数为420 s，远小于正萘的建立时间常数（7430 s）。其次，为了检验该方法对粉末样品的适用性，我们对掺杂并五苯的粉末萘样品进行了类似的实验。对于全氘代萘，质子极化率达到100 K热平衡值的10000倍，而对于非氘代萘，质子极化率的增益约为1000 K。这些结果表明，这种方法可能是有希望获得高的NMR灵敏度在感兴趣的系统中，通过应用DNP技术的感兴趣的客体/主体系统或通过转移的大极化在这样的系统，如并五苯掺杂的萘通过表面到最初未极化的感兴趣的系统。作为一个有趣的应用实例，本DNP技术可用于极大地提高用于NMR量子计算的系统的NMR灵敏度并初始化计算机。少

项目成果

K.Takegoshi: "^<13>C-^1H dipolar recoupling under very fast magic-angle spinning using virtual pulses"Solid State Nucl.Magn.Reson.. 13(4). 203-212 (1999)

K.Takegoshi：“使用虚拟脉冲在非常快的魔角旋转下^<13>C-^1H偶极重耦合”固态核磁力共振.. 13(4)。

K.Nomura et. al.: "Determination of the Complete Structure of a Uniformly Labeled Molecule by Rotational Resonance Solid-State NMR in the Tilted Rotating Frame"J.Am. Chem. Soc.. 121(16). 4064-4065 (1999)

K.野村等人。

K.Nomura: "Three-Dimensional Structure Determination of a Uniformly Labeled Molecule by Frequency-Selective Dipolar Recoupling Under Magic-Angle Spinning"J.Biol.Nucl.Magn.Reson.. 17(2). 111-123 (2000)

K.Nomura：“通过魔角旋转下的频率选择性偶极重耦合来确定均匀标记分子的三维结构”J.Biol.Nucl.Magn.Reson.. 17(2)。

K.Nomura: "Determination of the Complete Structure of a Uniformly Labeled Molecule by Rotational Resonance Solid-State NMR in the Tilted Rotating Frame"J. Am. Chem. Soc.. 121. 4064-4065 (1999)

K.Nomura：“通过倾斜旋转框架中的旋转共振固态核磁共振测定均匀标记分子的完整结构”J。

K.Takegoshi: "One- and two-dimensional ^<13>C-^1H/^<15>N-^1H dipolar correlation experiments in solids under fast magic-angle spinning for determining the peptide dihedral φ angle"Solid State Nucl.Magn.Reson.. 16(4). 271-278 (2000)

K.Takegoshi：“在快速魔角旋转下固体中的一维和二维 ^<13>C-^1H/^<15>N-^1H 偶极相关实验用于确定肽二面角 φ 角”固态核.磁力共振.. 16(4)。