Laboratory measurement of the 6-centimeter formaldehyde transitions
Formaldehyde transitions in ground and excited states at 6 cm, attaining line widths and hyperfine structure at 1-3 kHz
Thaddeus, P.↗
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Laboratory measurement of the 2-centimeter, 2/11/-2/12/ transition of normal formaldehyde and its carbon-13 and oxygen-18 species.
Beam-maser spectrometric measurements to an accuracy of about 100 Hz have been conducted of the 2(11)-2(12) transition for the isotopic species of greatest astronomical interest - i.e., H2CO, H2(13)CO, and H2C(18)O. The samples used were not isotopically enriched, monomeric formaldehyde vapors. For these species, all the coupling constants required to calculate the hyperfine structure of any rotational transition have been determined.
Tucker, K. D.↗
Beam maser measurements of CH3OH rotational transitions
Precise measurements of rotational transitions in methanol are reported that were made by means of beam maser spectrometers. No hyperfine structure was resolved at a resonance line width of 8 kHz. Accurate center frequencies for the transitions measured are useful for determining Doppler shifts for observed interstellar lines.
Gaines, L.↗
Tentative identification of U93.174 as the molecular ion N2H/+/
On the basis of a consideration of the rotation constant and the hyperfine structure together with the results of an ab initio structural calculation it is suggested that the three closely space new interstellar lines near 93.174 GHz reported by Turner (1974) might have been produced by the molecular ion N2H(+). It is pointed out that the identification of N2H(+) is reasonable also in terms of current ideas of interstellar chemistry.
Green, S.↗
Constraints on the molecular properties of interstellar X-ogen derived from radio observations
Twenty-eight X-ogen emission sources at 89.189 GHz have been detected and observed. Twenty of these are new X-ogen sources which also contain other interstellar molecules. No infrared stars are found to be X-ogen sources. A new rest frequency (89,188.65 MHz) is derived for X-ogen. It is shown that X-ogen is not SiC, C2H, or any molecule with spin-doubling, hyperfine structure, or both.
Hollis, J. M.↗
Mossbauer effect in dilute iron alloys
The effects of variable concentration, x, of Aluminum, Germanium, and Lanthanum atoms in Iron lattice on various Mossbauer parameters was studied. Dilute binary alloys of (Fe-Al), (Fe-Ge), (Fe-Al) containing up to x = 2 a/o of the dilute constituent were prepared in the form of ingots and rolled to a thickness of 0.001 in. Mossbauer spectra of these targets were then studied in transmission geometry to measure changes in the hyperfine field, peak widths isomer shifts as well as the ratio of the intensities of peaks (1,6) to the intensities of peaks (2,5). It was shown that the concept of effective hyperfine structure field in very dilute alloys provides a useful means of studying the effects of progressively increasing the solute concentration on host lattice properties.
Singh, J. J.↗
Measurement of the fundamental vibration-rotation spectrum of ClO
The ClO fundamental absorption band near 850/cm is observed, with a tunable PbSnTe diode laser used as a source of monochromatic radiation. The chlorine monoxide concentration in the absorption tube was measured indirectly via a UV transmission technique. Frequencies and assignments for the ClO lines, and band centers and rotational constants for the ClO fundamental vibration, are tabulated. Diatomic vibration-rotation transitions within and between electronic substates are discussed. The tunable diode laser is valuable for studying the hyperfine structure. The IR spectroscopic technique is developed in order to monitor chlorine monoxide concentration in the stratosphere, since the short-lived ClO is a crucial intermediate participant in reactions involving destruction of stratospheric ozone.
Menzies, R. T.↗
The quadrupole coupling constant of HNC
The letter reports resolved measurements of the quadrupole hyperfine structure of HNC (hydrogen isocyanide). These measurements were made in the direction of the cool interstellar dust cloud L134, and were used to make an experimental determination of a fundamental spectroscopic constant of HNC, its quadrupole coupling constant.
Snyder, L. E.↗
Global operators for delta functions - Extension to scattering states and the inclusion of spin
The paper presents an extension of the identities of Hiller, Sucher, and Feinberg for the evaluation of bound-state matrix elements of delta function operators, to scattering states. Attention is given to the technical difficulties encountered in the application of the scattering-state identities and how they can be overcome, including infrared singularities which arise if Coulomb forces are present and the velocity of the incident particle is small. In addition, both the scattering and bound-state identities are generalized to include spin-dependent contact interactions and spin-dependent Hamiltonians. Finally, it is stressed that the identities can be used to improve the accuracy of calculations of interest for diverse physical phenomena, ranging from positron annihilation to hyperfine structure.
Sucher, J.↗
A new global operator for two-particle delta functions
A new type of global operator to be used in evaluating matrix elements of two-particle delta functions is introduced. It is based, like the Trivedi one-particle operator, on the Poisson equation and is easier to apply than the method of Hiller, Sucher and Feinberg. After a test in the helium isoelectronic sequence, the new method is applied successfully to the interesting problem of hyperfine structure in muonic helium.
Drachman, R. J.↗
Laboratory and astronomical detection of the deuterated ethynyl radical CCD
Two rotational transitions of CCD, N = 1-2 at 144 GHz and 2-3 at 216 GHz, were detected in a laboratory glow discharge through deuterated acetylene and helium, after which one, N = 2-1, was detected toward the rich molecular cloud behind the Orion Nebula. The 144 GHz transition is a well-resolved spin doublet split by 55 MHz, the components of which contain hyperfine structure of the order of 1 MHz, so far only partially resolved. From observations toward two positions in Orion, at and near the Kleinmann-Low nebula, the column density of CCD is determined to be 1.8 x 10 to the 13th/sq cm and the isotopic ratio CCD/CCH = 0.05. CCD was not detected at two positions in TMC-1.
Vrtilek, J. M.↗
A polarisation correlation study of the excitation of the H2 d3Piu (v1 = 0, N1 = 1) level by electron impact
Full details are given of an experiment in which the three normalized Stokes' parameters characterizing the decay of the electron impact excited d3Piu (v1 = 0, N1 = 1) rotational level of H2 were determined in an electron-photon coincidence experiment at 25 eV impact energy and over the angular range of 20-60 deg. An analysis shows how these parameters are related to the state multipoles characterizing the excited state. The rather low degree of coherence which was observed is consistent with various depolarizing effects, namely the averaging over magnetic sublevels which occurred in both the excitation and decay channels and also the perturbations due to fine and hyperfine structure relaxations.
Mcconkey, J. W.↗
The spectroscopic observation of the CH radical in its a4Sigma(-) state
The first spectroscopic observation of CH in the a 4Sigma(0-) state are reported. The molecule was generated in a discharge-flow system in the reaction betweeen fluorine atoms and methane or between oxygen atoms and acetylene at a total pressure of about 1 Torr. Several resonances associated with the N = 1 - 0 transitions of 4Sigma(-) CH were observed at three separate laser wavelengths, while those for the N = 2 - 1 transition were observed at two wavelengths. Each observed Zeeman component consists of a well-split doublet arising from proton hyperfine structure. The reasons for assigning the observations to CH in its a 4Sigma(-) state are discussed.
Nelis, Thomas↗
The interstellar D1 line at high resolution
Observations at a resolving power or a velocity resolution are reported of the interstellar D(sub 1) line of Na I in the spectra of gamma Cas, delta Ori, epsilon Ori, pi Sco, delta Cyg, and alpha Cyg. An echelle grating was used in a double-pass configuration with a CCD detector in the coude spectrograph of the 2.7 m reflector at McDonald Observatory. At least 42 kinematically distinct clouds are detected along the light paths to the five more distant stars, in addition to a single cloud seen toward delta Cyg. The absorption lines arising in 13 of the clouds are sufficiently narrow and unblended to reveal clearly resolved hyperfine structure components split by 1.05 km/s. An additional 13 clouds apparently show comparably narrow, but more strongly blended, lines. For each individual cloud, upper limits T(sub max) and (v sub t)(sub max) on the temperature and the turbulent velocity, respectively, are derived by fitting the observed lines with theoretical absorption profiles.
Hobbs, L. M.↗
Matrix elements in the coupled-cluster approach - With application to low-lying states in Li
A procedure is suggested for evaluating matrix elements of an operator between wavefunctions in the coupled-cluster form. The use of the exponential ansatz leads to compact exponential expressions also for matrix elements. Algorithms are developed for summing all effects of one-particle clusters and certain chains of two-particle clusters (containing the well-known random-phase approximation as a subset). The treatment of one-particle perturbations in single valence states is investigated in detail. As examples the oscillator strength for the 2s-2p transition in Li as well as the hyperfine structure for the two states are studied and compared to earlier work.
Martensson-Pendrill, Ann-Marie↗
Calculation of polarization and anisotropy of resonant and fluorescent scattering
Formulas are derived for the swift calculation of the angular intensity distribution and the degree of polarization associated with the resonant and fluorescent scattering of radiation by atoms which occurs in the rarefied upper atmospheres of planets during sunlit airglow phenomena. Attention is given to spectral lines with hyperfine structure, which are indicative of nuclear spin processes. The method employed involves summations over Zeeman components, allowing an evaluation of polarization through the addition of underlying simple resonant and fluorescent scattering channels.
Chamberlain, Joseph W.↗
Molecules in an infrared cirrus cloud
One of the clouds that form the Polar Loop was observed in the 1(sub 10)-1(sub 11) 4.8 GHz transition of formaldehyde and in J equal to 1-0 transitions of CO-12 and CO-13 at 115 and 110 GHz resp. The cloud consists of several filaments. From the correlation of IRAS 60 and 100 microns intensities a color temperature of the dust of 21 K and a maximum optical depth of 3 x 10(exp -4) were derived. At one local maximum of the 100 micron intensity, the hyperfine structure of formaldehyde could be resolved. Since the infrared optical depth is small, the 100 micron intensity can be used as a measure of dust column density.
Meyerdierks, Horst↗
Spectral line profiles and luminosities of astrophysical water masers
The spectral line narrowing and rebroadening that occurs for astrophysical masers as a function of the emergent radiative flux is calculated for the prominent, 22 GHz masing transition of water. The increased line breadths due to hyperfine structure lead to reliable, essentially model-independent upper limits to the emergent flux that tend to be lower than other estimates for these masers. For many 22 GHz masers, including the outbursts in W49 and Orion, the observed line breadths are less than 0.9 km/s. For these, the upper limit to the emergent maser flux is 10 to the 10th K-sr when expressed in terms of the brightness temperature and the solid angle for beaming. It is concluded that the extreme brightness of the interstellar water masers is due to a high degree of beaming and not to more effective pumping.
Nedoluha, Gerald E.↗