Knowledge Bank

A new method far the microwave absorption spectroscope of molecular ions has been developed. In this system an axial magnetic field of $\sim 200$ Gauss is used to lengthen the negative glow region of a discharge to fill the length of an absorption cell. We find that ion densities are enhanced by approximately two orders of magnitude. This system has been used to observe in natural abundance $H12C18O+$(in real time on an oscilloscope) and $H12C17O+$. In addition, the molecular ions $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N16O+$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">40</mrow>}ArD+$ have been observed. The spectra of these two Species are one to two orders of magnitude weaker than that of the ``standard"" molecular ions $Hl2Cl6O+$, $H14N2+$, etc. $\mathrm{<mrow\; data-mjx-texclass="ORD">36</mrow>}ArD+$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">38</mrow>}ArD+$ have also been observed in natural abundance. Spectroscopic constants and details of the experimental method will be given. $\mathrm{<mrow\; data-mjx-texclass="ORD">\ast </mrow>}$Work supported by NASA Grant NAGW-189.