PRECISE THz MEASUREMENTS OF HCO+, N2H+, AND CF+FOR ASTROPHYSICAL OBSERVATIONS

Cazzoli, G.; Cludi, L.; Buffa, G.; Puzzarini, Cristina

doi:10.1088/0067-0049/203/1/11

Cited by 52 publications

(55 citation statements)

References 39 publications

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“…The two transitions were measured multiple times to determine their linecenters, which were 92 145 080.8(4) MHz for P(5) and 92 947 717.3(5) MHz for R (3). The difference between these frequencies, 802 636.5(7) MHz, agrees within its uncertainty with the sum of the J = 3 → 4 and J = 4 → 5 pure rotational transitions observed by Cazzoli et al, 28 356 734.2230(15) + 445 902.8721(15) = 802 637.0951 (21) MHz. The excellent agreement of this combination difference strongly suggests that our experiment does not suffer from any systematic errors that differ from one line to the next, beyond those at the sub-MHz level that result from scan-to-scan variations.…”

Section: Hco + Spectroscopysupporting

confidence: 67%

High-precision and high-accuracy rovibrational spectroscopy of molecular ions

Hodges

Perry

Jenkins

et al. 2013

The Journal of Chemical Physics

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We present a versatile new instrument capable of measuring rovibrational transition frequencies of molecular ions with sub-MHz accuracy and precision. A liquid-nitrogen cooled positive column discharge cell, which can produce large column densities of a wide variety of molecular ions, is probed with sub-Doppler spectroscopy enabled by a high-power optical parametric oscillator locked to a moderate finesse external cavity. Frequency modulation (heterodyne) spectroscopy is employed to reduce intensity fluctuations due to the cavity lock, and velocity modulation spectroscopy permits ion-neutral discrimination. The relatively narrow Lamb dips are precisely and accurately calibrated using an optical frequency comb. This method is completely general as it relies on the direct measurement of absorption or dispersion of rovibrational transitions. We expect that this new approach will open up many new possibilities: from providing new benchmarks for state-of-the-art ab initio calculations to supporting astronomical observations to helping assign congested spectra by combination differences. Herein, we describe the instrument in detail and demonstrate its performance by measuring ten R-branch transitions in the ν2 band of H3(+), two transitions in the ν1 band of HCO(+), and the first sub-Doppler transition of CH5(+).

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Section: Hco + Spectroscopysupporting

confidence: 67%

High-precision and high-accuracy rovibrational spectroscopy of molecular ions

Hodges

Perry

Jenkins

et al. 2013

The Journal of Chemical Physics

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“…Definition of the body-fixed Jacobi coordinates system for the CF + -He complex. (Cazzoli et al 2012). Their measurements enabled the prediction of rotational transitions with a good accuracy, up to 2.0-2.5 THz.…”

Section: Introductionmentioning

confidence: 93%

Induced rotational excitation of the fluoromethylidynium¹²CF⁺and¹³CF⁺through collision with helium

Ajili

Hammami

2013

A&A

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Aims. The present paper focuses on the calculation of the collision rate coefficients for rotational excitation of the 12 CF + and its isotopologue 13 CF + by He for temperature ranging from 10 to 300 K. Methods. A two-dimentional (2D) potential energy surface (PES) of the CF + (X 1 Σ + )-He( 1 S) system is calculated at the ab initio coupled cluster with single, double, and perturbative triple excitation level of theory with the aug-cc-pV5Z basis set. The basis set superposition errors were taken into account in our computation. Dynamical calculations of state-to-state rotational integral cross sections of the CF + by collision with He were performed using the close-coupling method. Results. The PES presents a global minimum of ∼212 cm −1 below the CF + -He dissociation limit. Collisional cross sections among the first 11 rotational levels of CF + were calculated for total energies up to 1500 cm −1 . Downward rate coefficients between the rotational levels were calculated for temperature ranging from 10 to 300 K. A propensity toward an even parity of ∆J is observed.

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“…Numbers in parentheses represent 1σ uncertainties. The two hfs components from this work were fitted together with 7 rotational lines from Cazzoli et al (2010) and Cazzoli et al (2012) (see Table 3). (a) Fixed to the experimental value by Gruebele et al (1986) .…”

Section: Discussionmentioning

confidence: 99%

Laboratory rotational ground state transitions of NH₃D⁺and CF⁺

Stoffels

Kluge

Schlemmer

et al. 2016

A&A

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Aims. This paper reports accurate laboratory frequencies of the rotational ground state transitions of two astronomically relevant molecular ions, NH 3 D + and CF + . Methods. Spectra in the millimetre-wave band were recorded by the method of rotational state-selective attachment of He atoms to the molecular ions stored and cooled in a cryogenic ion trap held at 4 K. The lowest rotational transition in the A state (ortho state) of NH 3 D + (J K = 1 0 −0 0 ), and the two hyperfine components of the ground state transition of CF + (J = 1−0) were measured with a relative precision better than 10 −7 . Results. For both target ions, the experimental transition frequencies agree with recent observations of the same lines in different astronomical environments. In the case of NH 3 D + the high-accuracy laboratory measurements lend support to its tentative identification in the interstellar medium. For CF + the experimentally determined hyperfine splitting confirms previous quantum-chemical calculations and the intrinsic spectroscopic nature of a double-peaked line profile observed in the J = 1−0 transition towards the Horsehead photon-dominated region (PDR).

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PRECISE THz MEASUREMENTS OF HCO⁺, N₂H⁺, AND CF⁺FOR ASTROPHYSICAL OBSERVATIONS

Cited by 52 publications

References 39 publications

High-precision and high-accuracy rovibrational spectroscopy of molecular ions

High-precision and high-accuracy rovibrational spectroscopy of molecular ions

Induced rotational excitation of the fluoromethylidynium¹²CF⁺and¹³CF⁺through collision with helium

Laboratory rotational ground state transitions of NH₃D⁺and CF⁺

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PRECISE THz MEASUREMENTS OF HCO+, N2H+, AND CF+FOR ASTROPHYSICAL OBSERVATIONS

Cited by 52 publications

References 39 publications

High-precision and high-accuracy rovibrational spectroscopy of molecular ions

High-precision and high-accuracy rovibrational spectroscopy of molecular ions

Induced rotational excitation of the fluoromethylidynium12CF+and13CF+through collision with helium

Laboratory rotational ground state transitions of NH3D+and CF+

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Product

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PRECISE THz MEASUREMENTS OF HCO⁺, N₂H⁺, AND CF⁺FOR ASTROPHYSICAL OBSERVATIONS

Induced rotational excitation of the fluoromethylidynium¹²CF⁺and¹³CF⁺through collision with helium

Laboratory rotational ground state transitions of NH₃D⁺and CF⁺