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Plummer, G. M.

Publications and source records attributed to Plummer, G. M..

9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The laboratory millimeter-wave spectrum of methyl formate in its ground torsional E state

Over 250 rotational transitions of the internal rotor methyl formate (HCOOCH3) in its ground v(t) = 0 degenerate (E) torsional substate have been measured in the millimeter-wave spectral region. These data and a number of E-state lines identified by several other workers have been analyzed using an extension of the classical principal-axis method in the high barrier limit. The resulting rotational constants allow accurate prediction of the v(t) = 0 E substate methyl formate spectrum below 300 GHz between states with angular momentum J not greater than 30 and rotational energy of not more than 350/cm. The calculated transition frequencies for the E state, when combined with the results of the previous analysis of the ground-symmetric, nondegenerate state, account for over 200 of the emission lines observed toward Orion in a recent survey of the 215-265 GHz band.

Plummer, G. M.↗
NASA NTRS1986

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).

Plummer, G. M.↗
NASA NTRS1985

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

The molecular ion H3O(+) is predicted to be an important component of the gas phase of interstellar clouds where it is calculated to be one of the most abundant molecular ions. Its detection would provide an indirect method of determining the abundance of the crucial species H2O. This fundamental molecule has no convenient low-lying transitions in the microwave or millimeter regions of the spectrum which can be excited under the normal low temperature conditions present in the interstellar medium. It is believed that the P(2,1) transition of H3O(+) in absorption at a frequency of 307 192.41 (5) MHz has been detected. The H3O(+) ion was produced in a magnetically enhanced negative glow discharge source.

Plummer, G. M.↗
NASA NTRS1984

C-13H3OH in OMC-1

Transition line data for C-13H3OH in OMC-1 were gathered with a superconducting tunnel junction receiver and a 512 channel spectrometer on a 10.4 m telescope at the Owens Valley Radio Observatory. The methanol was scanned at 236 GHz and an observational efficiency of 85 percent. The survey was carried out to complement the data base on the line frequencies of internal rotors such as methanol and thereby the resolution of the C-12/C-13 ratio toward the galactic center. The data indicated that previous emission lines attributed to CO(+) and CH3CHO are actually methanol emissions, and the associated C-12/C-13 ratio is about 30.

Blake, G. A.↗
NASA NTRS1984

Laboratory millimeter and submillimeter spectra of HNO and DNO

The identification of interstellar molecular species via the detection of one spectral line has recently become subject to close scrutiny. The radical HNO falls into the class of interstellar molecules identified in this manner. To corroborate this identification, observation of additional spectral lines is necessary. In this paper, laboratory millimeter and submillimeter wave spectra of both HNO and DNO are reported in the frequency region 150-500 GHz. Based on these spectral line measurements, models for HNO and DNO have been constructed to yield accurate frequencies for all rotational transitions of these species below 500 GHz involving J values smaller than 10. The spectral lines can be utilized by radio astronomers to confirm the identification of interstellar HNO and to search for interstellar DNO.

Sastry, K. V. L. N.↗
NASA NTRS1984

The millimeter and submillimeter laboratory spectrum of methyl formate in its ground symmetric torsional state

Over 200 rotational lines of methyl formate in its ground (v sub t = 0), symmetric (A) torsional state have been measured in the frequency range 140-550 GHz. Analysis of these and lower frequency transitions permits accurate prediction (below 0.1 MHz) of over 10,000 transitions at frequencies below 600 GHz with angular momentum J lower than 50. The measured spectral lines have permitted identification of over 100 new methyl formate lines in Orion.

Plummer, G. M.↗
NASA NTRS1984

Laboratory submillimeter transition frequencies of Li-7H and Li-6H

The fundamental (J = 1 - 0) rotational transition frequencies of Li-7H and Li-6H in their ground (v = 0) vibrational states and of Li-7H in its first excited (v = 1) vibrational state have been measured in the laboratory. Use of these transition frequencies should permit astronomical investigations of LiH abundances in red giant stars of high lithium abundance.

Plummer, G. M.↗
NASA NTRS1983

Measurement of the J = 0-1 rotational transitions of three isotopes of ArD(+)

The rotational transitions of all three isotopic species of ArD(+) in samples containing the Ar isotopes in their natural abundances have been measured by means of millimeter and submillimeter techniques that employ a magnetically enhanced abnormal glow discharge. All three transition frequency measurements were made from digitally averaged signals detected through a lock-in amplifier with a 10-msec time constant. The Ar-4OD(+) transition was easily visible in real time on an oscilloscope with SNR of about 15. It is noted that the observed transition of Ar-38D(+) is more than five orders of magnitude weaker than that due to HCO(+).

Bowman, W. C.↗