Submillimeter-Wave Spectra and Equilibrium Structures of the Hydrogen Halides

Lucia, Frank C. De; Helminger, Paul; Gordy, Walter

doi:10.1103/physreva.3.1849

Cited by 230 publications

(86 citation statements)

References 17 publications

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“…Any effects due to hyperfine depolarization were neglected as these would be negligible under the current experimental conditions, where photodissociation of the prepared E Ј⌺ 0ϩ ϩ state occurs on a time scale much faster than that of hyperfine depolarization. 41,42 It is found that model A, which corresponds to a purely perpendicular two-photon excitation and a parallel dissociation, provides the best fit to the experimental data. Although the experimentally observed ␤ L parameters are smaller in magnitude than those for model A, Table II.…”

Section: Photodissociation Of Hclmentioning

confidence: 96%

Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

Manzhos

Romanescu

Loock

et al. 2004

The Journal of Chemical Physics

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A formalism for calculating the angular momentum polarization of an atom or a molecule following two-photon excitation of a J-selected state is presented. This formalism is used to interpret the H atom photofragment angular distributions from single-photon dissociation of two-photon rovibronically state selected HCl and HBr prepared via a Q-branch transition. By comparison of the angular distributions measured using the velocity map imaging technique with the theoretical model it is shown that single-photon dissociation of two-photon prepared states can be used for pathway identification, allowing for the identification of the virtual state symmetry in the two-photon absorption and/or the symmetry of the dissociative state. It is also shown that under conditions of excitation with circularly polarized light, or for excitation via non-Q-branch transitions with linearly polarized light the angular momentum polarization is independent of the dynamics of the two-photon transition and analytically computable.

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Section: Photodissociation Of Hclmentioning

confidence: 96%

Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

Manzhos

Romanescu

Loock

et al. 2004

The Journal of Chemical Physics

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“…For comet C/2009 P1 (Garradd), the integration time was long (6−7 h for both HCl and HF). The integration time was less than 1 h for HCl in comet 103P/Hartley 2 ( (De Lucia et al 1971), were observed simultaneously, in the upper sideband of band 1b HIFI receiver. The I = 3/2 nuclear spin of 35 Cl and 37 Cl splits the J(1−0) line into three ΔF 1 = 0, −1, +1 hyperfine components (Cazzoli & Puzzarini 2004) with statistical-weight ratio 2:3:1, with the main component F 1 (5/2−3/2) being at the rest frequencies of 625.9188 GHz and 624.9778 GHz for H 35 Cl and H 37 Cl, respectively.…”

Section: Observationsmentioning

confidence: 99%

Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with theHerschelSpace Observatory

Bockelée‐Morvan

Biver

Crovisier

et al. 2014

A&A

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Context. Hydrogen chloride (HCl) and hydrogen fluoride (HF) are expected to be the main reservoirs of fluorine and chlorine over a wide range of conditions, wherever hydrogen is predominantly molecular. They are found to be strongly depleted in dense molecular clouds, suggesting freeze-out onto grains in such cold environments. We can then expect that HCl and HF were also the major carriers of Cl and F in the gas and icy phases of the outer solar nebula, and were incorporated into comets. Aims. We aimed to measure the HCl and HF abundances in cometary ices as they can provide insights on the halogen chemistry in the early solar nebula. Methods. We searched for the J(1−0) lines of HCl and HF at 626 and 1232 GHz, respectively, using the Heterodyne Instrument for the Far-Infrared (HIFI) onboard the Herschel Space Observatory. HCl was searched for in comets 103P/Hartley 2 and C/2009 P1 (Garradd), whereas observations of HF were conducted in comet C/2009 P1 (Garradd). In addition, observations of H 2 O and H 2 18 O lines were performed in C/2009 P1 (Garradd) to measure the H 2 O production rate at the time of the HCl and HF observations. Three lines of CH 3 OH were serendipitously observed in the HCl receiver setting. Results. HCl is not detected, whereas a marginal (3.6-σ) detection of HF is obtained. The upper limits for the HCl abundance relative to water are 0.011% and 0.022%, for comet 103P/Hartley 2 and C/2009 P1 (Garradd), respectively, showing that HCl is depleted with respect to the solar Cl/O abundance by a factor more than 6 +6 −3 in 103P/Hartley 2, where the error is related to the uncertainty in the chlorine solar abundance. The marginal HF detection obtained in C/2009 P1 (Garradd) corresponds to an HF abundance relative to water of (1.8 ± 0.5) × 10 −4 , which is approximately consistent with a solar photospheric F/O abundance. The inferred water production rate in comet C/2009 P1 (Garradd) is (1.1±0.3)×10 29 s −1 and (0.75±0.05)×10 29 s −1 on 17 and 23 February 2012, respectively. CH 3 OH abundances relative to water are 2.7 ± 0.3% and 3.4 ± 0.6%, for comets 103P/Hartley 2 and C/2009 P1 (Garradd), respectively. Conclusions. The observed depletion of HCl suggests that HCl was not the main reservoir of chlorine in the regions of the solar nebula where these comets formed. HF was possibly the main fluorine compound in the gas phase of the outer solar nebula. However, this needs to be confirmed by future measurements.

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“…Initially of interest as a potential coolant for molecular clouds, hydrogen chloride (HCl) was first detected in the J = 1-0 transition at 625.918 GHz (De Lucia et al 1971) toward IRc2 in Orion A, in emission, by Blake et al (1985), and in absorption against dust continuum in Sgr B2, by Zmuidzinas et al (1995), both on board the NASA Kuiper Airborne Observatory with a beam width of 2. 3.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Survey of Hydrogen Chloride in the Galaxy

Peng

Yoshida

Chamberlin

et al. 2010

ApJ

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We report new observations of the fundamental J = 1-0 transition of HCl (at 625.918 GHz) toward a sample of 27 galactic star-forming regions, molecular clouds, and evolved stars, carried out using the Caltech Submillimeter Observatory. Fourteen sources in the sample are also observed in the corresponding H 37 Cl J = 1-0 transition (at 624.978 GHz). We have obtained clear detections in all but four of the targets, often in emission. Absorptions against bright background continuum sources are also seen in nine cases, usually involving a delicate balance between emission and absorption features. From RADEX modeling, we derive gas densities and HCl column densities for sources with HCl emission. HCl is found in a wide range of environments, with gas densities ranging from 10 5 to 10 7 cm −3 . The HCl abundance relative to H 2 is in the range of (3-30) × 10 −10 . Comparing with the chlorine abundance in the solar neighborhood, this corresponds to a chlorine depletion factor of up to ∼400, assuming that HCl accounts for one-third of the total chlorine in the gas phase. The [ 35 Cl]/[ 37 Cl] isotopic ratio is rather varied, from unity to ∼5, mostly lower than the terrestrial value of 3.1. Such variation is highly localized, and could be generated by the nucleosynthesis in supernovae, which predicts a 37 Cl deficiency in most models. The lower ratios seen in W3IRS4 and W3IRS5 likely confine the progenitors of the supernovae to stars with relatively large mass ( 25 M ) and high metallicity (Z ∼ 0.02).

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Submillimeter-Wave Spectra and Equilibrium Structures of the Hydrogen Halides

Cited by 230 publications

References 17 publications

Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with theHerschelSpace Observatory

A Comprehensive Survey of Hydrogen Chloride in the Galaxy

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