Laboratory and radio-astronomical spectroscopy of the
hyperfine structure
 of N<sub>2</sub>D$\mathsf{^+}$

Dore, Luca; Caselli, P.; Beninati, Sabina; Bourke, Tyler L.; Myers, Philip C.; Cazzoli, G.

doi:10.1051/0004-6361:20034025

Cited by 40 publications

(59 citation statements)

References 38 publications

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“…In general, we used the symmetric frequency switch mode and the facility autocorrelator; in Table 1, we summarize the main observational parameters. The frequencies of the N 2 H + (1−0), N 2 D + (2−1) and N 2 D + (3−2) have been updated following the recent determinations of Dore et al (2004); the values in the table refer to the F 1 F = 2 3 → 1 2, 2 3 → 1 2, and 4 5 → 3 4 hyperfine components of the N 2 H + (1−0), N 2 D + (2−1) and N 2 D + (3−2) transitions, respectively. For N 2 H + (3−2) we used the frequency of the 2 1 → 1 0 component as determined by Caselli et al (2002a).…”

Section: Observationsmentioning

confidence: 99%

Observations of L1521F: A highly evolved starless core

Crapsi

Caselli

Walmsley

et al. 2004

A&A

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161

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Abstract. We observed the pre-stellar core L1521F in dust emission at 1.2 mm and in two transitions each of N 2 H + , N 2 D + , C 18 O and C 17 O in order to increase the sample of well studied centrally concentrated and chemically evolved starless cores, likely on the verge of star formation, and to determine the initial conditions for low-mass star formation in the Taurus Molecular Cloud. The dust observation allows us to infer the density structure of the core and together with measurements of CO isotopomers gives us the CO depletion. N 2 H + and N 2 D + lines are good tracers of the dust continuum and thus they give kinematic information on the core nucleus. We derived in this object a molecular hydrogen number density n(H 2 ) ∼ 10 6 cm −3 and a CO depletion factor, integrated along the line of sight, f D ≡ 9.5 × 10 −5 /x obs (CO) ∼ 15 in the central 20 , similar to the pre-stellar core L1544. However, the N(N 2 D + )/N(N 2 H + ) column density ratio is ∼0.1, a factor of about 2 lower than that found in L1544. The observed relation between the deuterium fractionation and the integrated CO depletion factor across the core can be reproduced by chemical models if N 2 H + is slightly (factor of ∼2 in fractional abundance) depleted in the central 3000 AU. The N 2 H + and N 2 D + linewidths in the core center are ∼0.3 km s −1 , significantly larger than in other more quiescent Taurus starless cores but similar to those observed in the center of L1544. The kinematical behaviour of L1521F is more complex than seen in L1544, and a model of contraction due to ambipolar diffusion is only marginally consistent with the present data. Other velocity fields, perhaps produced by accretion of the surrounding material onto the core and/or unresolved substructure, are present. Both chemical and kinematical analyses suggest that L1521F is less evolved than L1544, but, in analogy with L1544, it is approaching the "critical" state.

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Section: Observationsmentioning

confidence: 99%

Observations of L1521F: A highly evolved starless core

Crapsi

Caselli

Walmsley

et al. 2004

A&A

Self Cite

161

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“…The hyperfine structure of each transition has been predicted, assuming the hyperfine constants of Caselli et al (1995) and Dore et al (2004), by means of the SPCAT prediction program (Pickett 1991), and the hyperfine components included in each multiplet collect at least the 90% of the total intensity of the relevant J + 1 − J rotational transition. The line strength value, S i j , is defined as the square of the reduced matrix element of the rotation matrix (Brown & Carrington 2003)…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the unperturbed line frequency was recovered by a line shape analysis of the spectral profile modeled as a sum of hyperfine components with their frequency shift and intensity fixed at the values accurately predicted using the hyperfine constants known from literature (Caselli et al 1995;Dore et al 2004). Figure 1 illustrates a recording of the J = 5 ← 4 transition of the N 15 ND + isotopologue analyzed in this way.…”

Section: Experimental Details and Data Analysismentioning

confidence: 99%

“…The newly obtained laboratory data, together with the previously determined 14 N-hyperfine constants (Caselli et al 1995;Dore et al 2004) allowed for the calculation of very accurate rest frequencies for all four 15 N-containing variants of N 2 H + and N 2 D + at millimetre and submillimetre wavelengths, the predicted uncertainties being less that 0.005 km s −1 up to 1 THz.…”

Section: Introductionmentioning

confidence: 96%

“…In CO-depleted regions, also deuterium fractionation increases, therefore N 2 D + can be easily detected (see Dore et al 2004), however its 15 N-containing isotopologues have not been observed until now, owing also to the lack of any accurate spectral data.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Accurate rest frequencies for the submillimetre-wave lines of the $^{15}{\bf N}$-containing isotopologues of $\bf N_{2}H^+$ and $\bf N_{2}D^+$

Dore¹,

Bizzocchi

Esposti

et al. 2009

A&A

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The submillimetre-wave spectrum of the molecular ions N 15 NH + , 15 NNH + , N 15 ND + , and 15 NND + have been investigated in the laboratory using a source-modulation microwave spectrometer equipped with a negative glow discharge cell. The diazenylium ion was produced in a Ar/N 2 /H 2 (D 2 ) discharge plasma and the 15 N-containing isotopologues were observed in natural abundance. Six new rotational transitions for the protonated species and seven for the deuterated ones were accurately measured in the frequency range 270−760 GHz. These new laboratory measurements of the rare isotopologues of N 2 H + provide very precise rest frequencies at millimetre and submillimetre wavelengths useful for the radioastronomical identification of their rotational lines in the ISM.

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High‐resolution Microwave and Infrared Spectroscopy of Molecular Cations

Amano

2011

Handbook of High‐resolution Spectroscopy

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High‐resolution spectroscopic results for molecular cations obtained in the wavelength regions from microwave to infrared are summarized, with emphasis on more recent developments made after the year 2000. Starting at some early stage development made with mostly discharge sources, various experimental techniques developed for the detection of ions are discussed in some details. Recent results on specific molecular ions such as H 3 + and H 3 O + and their isotopic species are reviewed to show what kind of information could be obtained with high‐resolution spectroscopic techniques. The current status on a most challenging species in this field, CH 5 + , is described. Applications to and implications from astronomical observations are also described wherever they are relevant to spectroscopy.

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Laboratory and radio-astronomical spectroscopy of the hyperfine structure of N₂D$\mathsf{^+}$

Cited by 40 publications

References 38 publications

Observations of L1521F: A highly evolved starless core

Observations of L1521F: A highly evolved starless core

Accurate rest frequencies for the submillimetre-wave lines of the $^{15}{\bf N}$-containing isotopologues of $\bf N_{2}H^+$ and $\bf N_{2}D^+$

High‐resolution Microwave and Infrared Spectroscopy of Molecular Cations

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Laboratory and radio-astronomical spectroscopy of the hyperfine structure of N2D$\mathsf{^+}$

Cited by 40 publications

References 38 publications

Observations of L1521F: A highly evolved starless core

Observations of L1521F: A highly evolved starless core

Accurate rest frequencies for the submillimetre-wave lines of the $^{15}{\bf N}$-containing isotopologues of $\bf N_{2}H^+$ and $\bf N_{2}D^+$

High‐resolution Microwave and Infrared Spectroscopy of Molecular Cations

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Laboratory and radio-astronomical spectroscopy of the hyperfine structure of N₂D$\mathsf{^+}$