Direct observation of the fine structure transitions in the Ne+ and Ar+ ions with diode lasers

Yamada, Chikashi; Kanamori, Hideto; Hirota, Eizi

doi:10.1063/1.449520

Cited by 53 publications

(41 citation statements)

References 11 publications

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“…In the case of Kr þ 2 , these effects are even more pronounced than in Ar þ 2 because the spin-orbit coupling [23]). The analytical functions used to represent the potential energy curves of the AE and Å states have the form…”

Section: Potential Model With Explicit Treatment Of the Spin-orbit Inmentioning

confidence: 93%

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr₂⁺

Wüest¹,

Merkt²

2005

Molecular Physics

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Spectra of the v þ ¼ 55À74 vibrational levels of the I(1/2u) ground electronic state and the v þ ¼ 0À9 levels of the II(1/2u) excited electronic state of 84 Kr þ 2 and 84 Kr-86 Kr þ have been measured by pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopy. The spectra were recorded following (2 þ 1 0 ) resonance-enhanced multiphoton excitation via several vibrational levels of the 0 þ g Rydberg state of Kr 2 located below the Kr( 1 S 0 Þ þ Kr Ã (4p 5 5p[1/2](J ¼ 0)) dissociation limit. A combination of these results with earlier measurements of the vibrational level structure of the I(1/2u), I(3/2u) and II(1/2u) states of Kr þ 2 was used to determine two sets of analytical potential energy curves for the first three electronic states of ungerade (u) symmetry of Kr þ 2 . The first set of curves was obtained without explicit consideration of the spin-orbit interaction by adjusting the potential parameters of three independent curves to fit the experimental data. The second set of curves was determined using a global potential model with explicit treatment of the spin-orbit interaction by adjusting the potential parameters of the A 2 AE þ u and C 2 Å u electronic states and assuming an R-independent spin-orbit coupling constant. Both sets of curves reproduce the experimental observations to within 8 cm À1 . Although better agreement between calculated and observed vibronic energy levels was obtained with the former set of curves, this set requires a larger number of adjustable potential parameters (up to 12) and only accounts implicitly for the spin-orbit coupling. The latter set of curves offers the advantages of a global treatment of the u states, a much reduced number of adjustable parameters (only six), an explicit treatment of the spin-orbit interaction, and is in better agreement with ab initio quantum chemical predictions in the repulsive part of the potentials.

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Section: Potential Model With Explicit Treatment Of the Spin-orbit Inmentioning

confidence: 93%

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr₂⁺

Wüest¹,

Merkt²

2005

Molecular Physics

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“…Table 1 summarizes the stellar properties of the stars selected for this high-resolution spectroscopy follow-up. The scope of this study is to obtain high-resolution spectra of the [Ne II] line (12.81355 μm, Yamada et al 1985), and by determining the line center and studying the profiles, to obtain observational constraints on the emission mechanism of [Ne II]. The article is organized as follows: in Sect.…”

Section: Samplementioning

confidence: 99%

On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

Baldovin-Saavedra

Audard

Güdel

et al. 2012

A&A

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Context. The [Ne II] line 12.81 μm was proposed to be a good tracer of gas in the environments of proto-planetary disks; its origin is explained by different mechanisms: jets in outflows, photo-evaporative disk winds driven by stellar X-rays/EUV or by the X-ray irradiated proto-planetary disk atmosphere. Previous Spitzer studies gave hints toward the neon emitting mechanism by exploring correlations between the line luminosity and properties of the star-disk system. These studies concluded that the origin of the emission is likely related to accretion and outflows, with some influence from X-rays. Aims. We provide direct constraints on the origin of the [Ne II] emission using high-spatial and spectral resolution observations that allow us to study the kinematics of the emitting gas. In addition we compare the [Ne II] line with optical forbidden lines. Methods. We obtained high-resolution ground-based observations with VISIR-VLT for 15 stars and UVES-VLT for three of them. The stars were chosen for having bright neon emission lines detected with Spitzer/IRS. The velocity shifts and profiles are used to disentangle the different emitting mechanisms producing the [Ne II] line. A comparison between results from this study and previous high-resolution studies is also presented. Results. The [Ne II] line was detected in seven stars, among them the first confirmed detection of [Ne II] in a Herbig Be star, V892 Tau. In four cases, the large blueshifted lines indicate an origin in a jet. In two stars, the small shifts and asymmetric profiles indicate an origin in a photo-evaporative wind. CoKu Tau 1, seen close to edge-on, shows a spatially unresolved line centered at the stellar rest velocity, although cross-dispersion centroids move within 10 AU from one side of the star to the other as a function of wavelength. The line profile is symmetric with wings extending up to ∼±80 km s −1 . The origin of the [Ne II] line is unclear and could either be due to the bipolar jet or to the disk. For the stars with VLT-UVES observations, in several cases, the optical forbidden line profiles and shifts are very similar to the profile of the [Ne II] line, suggesting that the lines are emitted in the same region. A general trend observed with VISIR is a lower line flux when compared with the fluxes obtained with Spitzer. We found no correlation between the line full-width at half maximum and the line peak velocity. The [Ne II] line remains undetected in a large part of the sample, an indication that the emission detected with Spitzer in those stars is likely extended.

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“…The continuum is detected from each target. We measure equivalent widths for the [ Ne ii] fine-structure line ( 2 P 3/2 -2 P 1/2 ) at 12:81355 AE 0:00002 m ( Yamada et al 1985) of 62 AE 11 8 for TW Hya and 2 upper limits of <10 and <11 8 for nondetections from BP Tau and DP Tau, respectively. The upper limits are calculated by assuming the same line profile as that of TW Hya, and they would be larger if the hypothetical lines from these objects were broader.…”

mentioning

confidence: 99%

High‐Resolution Spectroscopy of [Neii] Emission from TW Hydrae

Herczeg

Najita

Hillenbrand

et al. 2007

ApJ

102

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We present high-resolution echelle spectra of [Ne ii] 12.81 m emission from the classical T Tauri star (CTTS) TW Hya, obtained with MICHELLE on Gemini North. The line is centered at the stellar radial velocity and has an intrinsic FWHM of 21 AE 4 km s À1. The line width is broader than other narrow emission lines typically associated with the disk around TW Hya. If formed in a disk, the line broadening could result from turbulence in a warm disk atmosphere, Keplerian rotation at an average distance of 0.1 AU from the star, or a photoevaporative flow from the optically thin region of the disk. We place upper limits on the [Ne ii] emission flux from the CTTSs DP Tau and BP Tau. Subject headingg s: infrared: stars -planetary systems: protoplanetary disks -stars: pre-main-sequence Online material: color figure

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Direct observation of the fine structure transitions in the Ne+ and Ar+ ions with diode lasers

Cited by 53 publications

References 11 publications

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr₂⁺

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr₂⁺

On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

High‐Resolution Spectroscopy of [Neii] Emission from TW Hydrae

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Direct observation of the fine structure transitions in the Ne+ and Ar+ ions with diode lasers

Cited by 53 publications

References 11 publications

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr2+

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr2+

On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

High‐Resolution Spectroscopy of [Neii] Emission from TW Hydrae

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Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr₂⁺

Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lyingungeradestates of Kr₂⁺