Measurement of Nuclear Spin Conversion Rates in Molecules

分子中核自旋转化率的测量

• 批准号: 11640390
• 负责人: TAKAGI Kojiro
• 金额: $ 2.3万
• 依托单位: Toyama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 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/grant/KAKENHI-PROJECT-11640390/
• 关键词: Nuclear spin isomer; Laser spectroscopy; Infrared spectroscopy; Methyl alcohol; Methyl fluoride; Light induced drift; オルト・パラ変換; 内部回転; メタノール分子

The purpose of the project is the measurement of the nuclear spin conversion rates of methanol and its isotopic species by applying the light induced drift method. Theoretically, the purpose is the calculation of torsion-rotation energy levels of the A and E species of methanol and its isotopic species and the analysis of the conversion rates to determine the energy difference between the A and E species. Our purpose also includes the observation of the change of the conversion rates by the level crossing in applied electric field.In accordance with the description for Research Plan, the research results are as follows. We developed an experimental setup for the light induced drift and measurement of conversion rates. However, we found that the stability of the probe laser was not enough in the frequency and output power to measure the conversion rates with a required precision. We have developed this stable probe laser. In an improved setup we have observed the ortho-para conversion rate for ^<13>CH_3F and its increase in applied electric fields. However, we have to improve experimental accuracy further before we study the methanol molecule.As for the determination of precise energy levels and the torsional potential barrier, we have obtained the following results. In references (3) and (5), we experimentally determined torsion-rotation energy levels with a high precision. Theoretically, torsion-rotation Hamiltonian with new higher order terms was developed and applied to determine energy levels for CH_3^<18>OH in reference (1).Theory to calculate centrifugal distortion constants was developed for methanol in reference (2). Centrifugal distortion constants for CH_3OH and CD_3OH including isotopic species have been calculated in references (4) and (6), respectively.

该项目的目的是通过应用光致漂移方法测量甲醇及其同位素物种的核自旋转换率。从理论上讲，目的是计算甲醇及其同位素的A和E物种的扭转-旋转能级，并分析转化率以确定A和E物种之间的能量差。我们的目的也包括观察在外加电场中能级交叉所引起的转化率的变化。根据研究计划的描述，研究结果如下。我们开发了一个实验装置的光致漂移和转换率的测量。然而，我们发现探测激光器的频率和输出功率的稳定性不足以以所需的精度测量转换率。我们已经开发了这种稳定的探测激光器。在一个改进的装置中，我们观察到了^CH_3F的邻-对位转化率及其随外加电场的增加。<13>然而，在对甲醇分子进行研究之前，我们还需要进一步提高实验精度，在精确能级和扭转势垒的确定方面，我们得到了以下结果。在参考文献（3）和（5）中，我们用实验方法测定了高精度的扭转-转动能级。在理论上，文献[1]发展了含新高阶项的扭-转哈密顿量，并用于确定CH_3 ^OH的能级，文献[2]发展了计算甲醇离心畸变常数的理论。<18>文献（4）和（6）分别计算了CH_3OH和CD_3OH的离心畸变常数（包括同位素）。

项目成果

Z.D.Sun,F.Matsushima,S.Tsunekawa and K.Takagi: "Sub-Doppler spectroscopy of the C-O stretching fundamental band of methanol by use of microwave sidebands of CO_2 laser lines"J.Opt.Soc.Am.. B17. 2068-2080 (2000)

Z.D.Sun、F.Matsushima、S.Tsunekawa 和 K.Takagi：“利用 CO_2 激光线的微波边带对甲醇的 C-O 拉伸基带进行亚多普勒光谱”J.Opt.Soc.Am.. B17。

Z.D.Sun,F.Matsushima,S.Tsunekawa and K.Takagi: "Infrared-microwave double-resonance spectroscopy of CH_3OH by use of sidebands of CO_2 laser lines"J.Opt.Soc.Am.. B16. 1447-1454 (1999)

Z.D.Sun、F.Matsushima、S.Tsunekawa 和 K.Takagi：“利用 CO_2 激光线的边带对 CH_3OH 进行红外-微波双共振光谱”J.Opt.Soc.Am.. B16。