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Current ResearchStudents in the Oka group use a variety of laser radiation sources to conduct high-resolution high-sensitivity spectroscopy of molecular ions in laboratory plasmas. Our studies are closely related to astronomy, and we also observe the absorption and emission spectra of these ions in astronomical objects. The unifying theme of our studies is the understanding of the quantum mechanics and dynamics of fundamental molecular ions and their behavior in different laboratory and astronomical environments. Molecular Ions in Laboratory PlasmasThe Oka group produces molecular ions in plasmas by applying an electric field onto low pressure gas cells. In these discharges, the ions are produced in small concentrations and we detect them using very high sensitivity laser spectroscopy. A new project underway is to create ions by coupling electric discharges with supersonic expansions. In these expansions, the ions are rotationally cooled, which greatly simplifies their spectra. These expansions also provide a nearly collisionless environment allowing transient species (which would be quickly destroyed by collisions in a steady-state plasma) to be observed. In collaboration with theorists we study the molecular ions' intramolecular dynamics, which are often unusual. Recent projects include the study of CH5+ (a molecule with five identical particles), CH2+ (a Renner-Teller molecule), vibrational overtones of H3+ (which provide crucial tests of three-atom ab initio calculations), vibrational spectroscopy of HCNH+ and HCO+ hot bands, and electronic spectroscopy of C2+ and N2+. Molecular Ions in Astronomical PlasmasThe ongoing unification of chemistry and astronomy has revealed that "molecular clouds" are the birthplace of stars and that the chemical evolution of the clouds plays a crucial step in star formation. The idea has emerged in these studies that molecular ions play pivotal roles in such processes. Since our discovery in 1980 of the laboratory infrared spectrum of H3+, the most fundamental molecular ion, we have been actively engaged in a search for this ion in interstellar space. This search finally paid off in 1996 with the detection of H3+ in two molecular clouds. Further work has demonstrated the abundance of H3+ in molecular clouds, diffuse clouds, and even the Galactic Center. Our laboratory studies have also led to the detection of ions such as HCNH+ and H3O+ in molecular clouds. Follow more information, select any of the following:
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