Far-Infrared and Infrared Spectroscopy of Molecular Ions

该项目的目的是测量分子离子的远红外光谱。为此，我们首先研制了分子离子光谱系统，并改进了可调谐CO_2激光系统。然后，我们观察了HeH^+及其同位素的转动光谱，并对这些光谱进行了分析。我们进一步研究了质子化稀有气体NeH^+、ArH^+和KrH^+。在红外波段，我们研制了一套频率可调谐的高精度CO_2激光系统。该系统已成功地应用于红外-微波双共振光谱研究中，观察到甲醇分子的转动光谱。根据研究计划中的说明，本文的研究成果概括如下。(1)HeH^+转动光谱的研究通过对HeH ^+四种同位素的远红外转动光谱的观测，确定了精确的分子常数。(2)其他质子化稀有气体的远红外光谱研究我们观测了NeH^+、ArH^+和KrH^+及其同位素的转动光谱，从而确定了它们的精确分子常数。(3)高频率精度可调谐CO_2激光器的研制了一台稳频CO_2激光器，用作002激光器的频率基准，提高了002激光器的频率精度。(4)利用可调谐CO_2激光器的双共振光谱，精确地观察到甲醇分子振动激发态的转动跃迁。本文发展了含内转子分子的哈密顿量，并应用于分析所观察到的跃迁。

The purpose of the project is the measurement of far-infrared spectra of molecular ions. For this purpose we first developed the spectroscopic system for molecular ions and improved the frequency-tunable CO_2 laser system. We then observed the rotational spectra of HeH^+ and its isotopic species and analyzed these spectra. We further studied the following protonated rare gases, NeH^+ ArH^+ and KrH^+In the infrared region, we developed a frequency-tunable CO_2 laser system with a high frequency accuracy. This system has been used successfully to the study of infrared-microwave double resonance spectroscopyto observe the rotationalspectrum of the methanol molecule. The spectrum has been also studied theoretically.In accordance with the description for Research Plan, the research results are summarized as follows.(1) Study of rotational spectrum of HeH^+Far-infrared rotational spectra of the four isotopic species of HeH^+ have been observed to determine precise molecular constants.(2) Study of the far-infrared spectra of the other protonated rare gasesRotational spectra of NeH^+ ArH^+ and KrH^+ and their isotopomers have been observed to determine their precise molecular constants.(3) Development of a frequency-tunable CO_2 laser with a high frequency accuracyA frequency stabilized CO_2 laser has been produced, which is used as a frequency reference to improve the frequency accuracy of the 002 laser.(4) Double resonance spectroscopy using the frequency-tunable CO_2 laserRotational transitions in the excited vibrational state of methanol have been observed accurately. The Hamiltonian for a molecule with an internal-rotor has been developed and applied to the analysis of observed transitions.