High precision terahertz spectroscopy focused on the detection of weak transions

在太赫兹波段发展了对分子阳离子和阴离子的高精度光谱测量。我们成功地获得了在分子科学发展中发挥重要作用的以下结果：1)OD-分子阴离子的转动结构的光谱测量。为了扩展这一系列工作，我们研究了我们以前测量到的OH的去中性物种--OD离子的转动光谱。利用可调谐远红外光谱仪获得了四条新的纯旋转线的精确频率。测量频率的高精度使我们能够将以前从红外光谱工作中获得的转动常数提高两个数量级。使用邓纳姆系数的分析也在进行中。2)测量了H2D^+和D2H^+、H2D^+和D2H^+的旋转线频率。是…吗？H_3~+的同位素种类较多，可能是研究空间化学史的关键物种。十多年前，我们测量了一些纯旋转线的频率。现在我们重新测量旋转线的频率，并将测量扩展到光谱仪可观测区域中的更多线。3)对可调谐远红外光谱仪进行了改进，采用了新型的样品池。扩展负辉光放电的放电样品池已被前人证明在分子阳离子的研究中是有效的。它可以在外加磁场扩展的辉光放电区产生更多的离子。我们改进了样品池以采用这种类型的放电。此外，还准备了新的电源和质量流量控制器，以保持足够稳定的放电，以执行精确的测量。通过观察N_2H~+离子的旋转线，证实了该光谱仪的性能。该光谱仪在未来的分子阳离子测量中将是有效的。较少

High precision spectroscopic measurements of molecular cations and anions which are very difficult to investigate were developed in the terahertz region. We successfully obtained the following results that play important roles in the development of molecular science.1) Spectral measurements of the rotational structure of OD- molecular anion.Rotational spectraof OD ion which is the deutrated species of OH previously measured by us were investigated to extend this series of works. Precise frequencies of the four new pure-rotational lines were obtained by using Tunable Far-infrared spectrometer. The high precision of the measured frequencies enabled us to improve the rotational constants previously obtained from IR spectroscopic works by two orders of magnitudes. An analysis using Dunham coefficients are also in progress. The drafts of the paper reporting the present results are in preparation.2) Measurements of the rotational line frequencies of H2D^+ and D_2H^+.H_2D^+ and D_2H^+. is the … More isotopic species of H_3^+ which is supposed to be the key species in the study of the chemical history of the space. We measured the frequencies of some of the pure rotational lines more than ten years ago. We now remeasure the frequencies of the rotational lines, and extend the measurements to more lines which are in the observable region of our spectrometer. The measurement is still in progress and in preparation to submit.3) Improvements of the tunable far-infrared spectrometer to adopt new type of sample cell.A discharge sample cell using the extended negative glow discharge has been proved to be effective in the investigation of molecular cations by preceding researchers. It can generate more ions in the glow discharge region extended by applying external magnetic field. We improved our sample cell to adopt this type of discharge. Also, new power supply and mass flow controller were prepared to keep the discharge stable enough to perform the precise measurements. The performance of the spectrometer was confirmed by observing the rotational lines of N_2H^+ ion.. The spectrometer will be effective in the future measurements of molecular cations. Less