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De Lucia, F. C.

Publications and source records attributed to De Lucia, F. C..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

The submillimeter-wave spectrum of propionitrile (C2H5CN)

The laboratory millimeter-wave and submillimeter-wave rotational spectrum of propionitrile (ethyl cyanide, C2H5CN) in its ground vibrational state has been extended through J = 70 and K(sub a) = 36. Transitions measured in this study are in the frequency range 250-610 GHz. A fit of 952 transitions including 732 new measurements to a Watson A-reduced Hamiltonian has yielded a complete set of quartic and sextic distortion constants, in addition to six octic distortion constants. Internal rotation and hyperfine splittings have not been resolved, so they are not included in the analysis. Predicted transition frequencies for a large number of additional transitions of interest to radioastronomers are provided.

Pearson, J. C.↗
NASA NTRS1986

An interstellar line coincident with the P(2,1) transition of hydronium (H3O+)

Double-sideband observations of the Orion KL nebular region with the NRAO 12 m radiotelescope in March 1986 detected a weak emission spectral line that coincided with the P(2,1) rotation-inversion transition of H3O+. Spectral maps are provided for the observed line at 307,192 MHz with 2 and 1 MHz resolution. The line parameters, along with a calculated transition dipole moment of 1.44 D, are used to estimate column densities of 7.7 and 8.7 x 10 to the 13/sq cm for excitation temperatures of 50 and 90 K, respectively. A minimum H2 density of 1 million/cu cm is estimated for the region if the thermalization of the transition to the excitation temperatures is to occur. Finally, fractional abundances of H2O in the Orion cloud are projected to be 1/100,000 and 1/1 million for the nonthermal and thermal transition cases, respectively.

Hollis, J. M.↗
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

Prediction and assignment of the FIR spectrum of hydrogen peroxide

Millimeter and submillimeter microwave studies are used to predict and assign the FIR rotational-torsional spectrum of hydrogen peroxide. Special attention is given to the strong Q-branch features that have recently been used by Traub and Chance to place an upper limit on the atmospheric abundance of hydrogen peroxide. In addition, 67 new transitions are reported in the 400-1000 GHz region.

Helminger, P.↗
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

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 NTRS1984

The laboratory millimeter and submillimeter spectrum of HCO

The rotational absorption frequencies of 68 new lines from the HCO radical in its ground electronic state have been measured in the millimeter and submillimeter spectral region. The large zero-field data set acquired has allowed the complex spectrum of this light asymmetric rotor with unpaired electronic spin and magnetic hyperfine interactions to be completely analyzed to within experimental accuracy for the first time. The wide range of states observed provides a highly accurate map of the rotational frequencies of the formyl radical, which should enable the abundance and excitation of interstellar HCO to be examined in detail.

Blake, G. A.↗
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.↗
NASA NTRS1982

Millimeter and submillimeter laboratory spectroscopy - Recent results of astrophysical interest

Recent laboratory spectroscopic results on the transient neutral species CCH, NH2, and NaH, the molecular ions HCO(+), N2H(+), and CO(+), and the light asymmetric internal rotor HOOH are reviewed. It is shown that the shorter millimeter and submillimeter spectral region offers a number of advantages, even in the laboratory. Attention is also given to the requirements for theoretical models capable of the accurate spectral predictions required for many astrophysical applications. The results presented here are seen as demonstrating that millimeter and submillimeter microwave spectroscopy provides a sensitive and flexible means of studying short-lived species in the laboratory. It is believed that, in combination with the appropriate theoretical approach, studies of this type are capable of providing accurate spectral maps over wide spectral regions for most species of astrophysical importance.

De Lucia, F. C.↗
NASA NTRS1981

Laboratory millimeter and submillimeter spectrum of CCH

The laboratory millimeter and submillimeter spectrum of the interstellar radical CCH has been observed and measured in the 174-350 GHz region. The fitted spectral constants are in excellent agreement with those determined from radioastronomical measurement.

Sastry, K. V. L. N.↗
NASA NTRS1981

Laboratory millimeter and submillimeter spectra of CO/+/

The strong electric dipole-allowed transitions of the molecular ion CO(+) in the region 235-470 GHz have been measured in the laboratory. The laboratory spectra at 235 GHz appear to confirm the claim by Erickson et al. (1981) to have observed CO(+) in OMC-1.

Sastry, K. V. L. N.↗
NASA NTRS1981

Millimeter and submillimeter spectra of HCO/+/ and DCO/+/

The J = 0-1 transitions of six different isotopic forms of the HCO(+) molecular ion, which were investigated by Woods et al. (1975), are considered. The extension of this work into the shorter millimeter and submillimeter region is reported here, as is the measurement of these spectra through J = 4-5 for HCO(+) and J = 5-6 for DCO(+). It is noted that these measurements can be used to determine accurate rotational constants and rest frequencies for these astrophysically important species. Tables listing the observed rotational constants and spectral constants of HCO(+) and DCO(+) are included.

Sastry, K. V. L. N.↗