Grant M. Plummer

The production of large concentrations of molecular ions in the lengthened negative glow region of a discharge

A technique for enhancement of positive molecular ion concentrations in a glow discharge is presented. The technique consists of modifying an anomalous glow discharge by the addition of a longitudinal magnetic field of up to 300 G. Enhancements in the ion signal strength, as measured by millimeter and submillimeter wave spectroscopy, are approximately two orders of magnitude. Evidence is presented that the magnetic field increases the length of the ion rich negative glow by restricting inside a small diameter tube the ionizing electrons accelerated by the large cathode drop of an anomalous glow discharge.

Submillimeter spectra and molecular constants of 6LiH, 7LiH, 6LiD, and 7LiD

The fundamental J=1←0 rotational transitions of 7LiH in its two lowest vibrational states and of 6LiH in its ground vibrational state have been measured. In addition, the J=2←1 transitions of 7LiD in its two lowest vibrational states and of 6LiD in its ground vibrational state have been studied. The measured submillimeter transition frequencies have been combined with previous millimeter data on 6LiD and 7LiD into a data set which has been successfully analyzed according to the theories of Herman, Asgharian, and Watson, which treat the problem of Born–Oppenheimer breakdown.

Measurement of the J=0→1 rotational transitions of three isotopes of ArD+

Microwave spectra −ArD+ are reported. Rotational transitions in 40ArD+ and 38ArD+ are reported and analyzed. (AIP)

The millimeter and submillimeter spectrum of CF

The application of a recently described technique for producing significantly enhanced concentrations of molecular ions for spectroscopic study to the detection and measurement of the millimeter and submillimeter wave spectrum of CF(+) is reported. The experimental procedure is discussed, and the measured absorption frequencies are shown and compared with those calculated from spectral constants. These constants are given together with those from the infrared spectrum by Kawaguchi and Hirota (1985).

Laboratory measurement of the P(2,1) submillimeter transition frequency of H3O+

The P(2,1) transition frequency of the rotation‐inversion spectrum of the molecular ion H3O+ has been measured in the laboratory to be 307u2009192.41u2009(5) MHz. Measurement to this frequency should enable radioastronomers to search for H3O+ in interstellar clouds that are warm enough to excite this transition in emission.

C-type transitions in methyl formate

Based on previously determined spectral constants for methyl formate in its ground torsional degenerate substate, the frequencies and intensities of forbidden c-type transitions in this molecule, which is represented by a large number of lines in OMC-1, are calculated along with other forbidden transitions labeled x-type. The stronger c-type transitions below 300 GHz with angular momentum quantum number of 30 or less and with upper state rotational energy of 350/cm or less are included in a list of spectral frequencies presented in this paper. Because the c-type transitions borrow intensity from the b-type transitions, the intensities of strongly affected b-type spectra are recalculated and presented. 11 references.