Atomic lifetime measurements obtained by the use of laser ablation and selective excitation spectroscopy

Measures, Raymond M.; Drewell, N.H.; Kwong, H. S.

doi:10.1103/physreva.16.1093

Cited by 36 publications

(9 citation statements)

References 17 publications

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“…Other accurate lifetimes have been measured by TRLIF Kwiatkowski et al 1981;Kwong & Measures 1980;Measures et al 1977) and level-crossing (Becker et al 1977); these data all agree well with Cooper et al's, and have comparable uncertainties. Other accurate g f -values were produced by Tozzi et al (1985), also based upon FTS BFs but normalised to Kwiatkowski et al's lifetimes, and Blackwell et al (1984Blackwell et al ( , 1986b, who measured relative g f -values using absorption spectroscopy and set them to an absolute scale with the lifetimes of , Kwiatkowski et al (1981) and Becker et al (1977).…”

Section: Oscillator Strengthssupporting

confidence: 77%

The elemental composition of the Sun

Scott

Asplund

Grevesse

et al. 2014

A&A

265

202

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We redetermine the abundances of all iron group nuclei in the Sun, based on neutral and singly-ionised lines of Sc, Ti, V, Mn, Fe, Co and Ni in the solar spectrum. We employ a realistic 3D hydrodynamic model solar atmosphere, corrections for departures from local thermodynamic equilibrium (NLTE), stringent line selection procedures and high quality observational data. We have scoured the literature for the best quality oscillator strengths, hyperfine constants and isotopic separations available for our chosen lines. We find log Sc = 3.16 ± 0.04, log Ti = 4.93 ± 0.04, log V = 3.89 ± 0.08, log Cr = 5.62 ± 0.04, log Mn = 5.42 ± 0.04, log Fe = 7.47 ± 0.04, log Co = 4.93 ± 0.05 and log Ni = 6.20 ± 0.04. Our uncertainties factor in both statistical and systematic errors (the latter estimated for possible errors in the model atmospheres and NLTE line formation). The new abundances are generally in good agreement with the CI meteoritic abundances but with some notable exceptions. This analysis constitutes both a full exposition and a slight update of the preliminary results we presented in Asplund et al. (2009, ARA&A, 47, 481), including full line lists and details of all input data we employed.

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Section: Oscillator Strengthssupporting

confidence: 77%

The elemental composition of the Sun

Scott

Asplund

Grevesse

et al. 2014

A&A

265

202

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“…234 through 249, and the information provided in Table VII). Excited-state lifetimes, [241][242][243] obtained by measuring the fluorescence decay after the laser pulse is terminated, is indeed a useful parameter when measured at different delays after the formation of the plasma: as discussed by Measures et al back in 1977, 241 its temporal behavior provides direct information about electron quenching and self-absorption effects. The time lag observed in reaching the peak of the signal when collisionally induced fluorescence is compared with direct line fluorescence provides information about the excitation rates and associated cross-sections; 244,245 vice versa, if the cross-section is known or can be calculated, the ratio between the fluorescence signals resulting from direct coupling and collisional coupling can be used to evaluate the electron number density.…”

Section: 112mentioning

confidence: 99%

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

2010

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Laser-induced breakdown spectroscopy (LIBS) has become a very popular analytical method in the last decade in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis. The technique has a remarkably wide applicability in many fields, and the number of applications is still growing. From an analytical point of view, the quantitative aspects of LIBS may be considered its Achilles' heel, first due to the complex nature of the laser–sample interaction processes, which depend upon both the laser characteristics and the sample material properties, and second due to the plasma–particle interaction processes, which are space and time dependent. Together, these may cause undesirable matrix effects. Ways of alleviating these problems rely upon the description of the plasma excitation-ionization processes through the use of classical equilibrium relations and therefore on the assumption that the laser-induced plasma is in local thermodynamic equilibrium (LTE). Even in this case, the transient nature of the plasma and its spatial inhomogeneity need to be considered and overcome in order to justify the theoretical assumptions made. This first article focuses on the basic diagnostics aspects and presents a review of the past and recent LIBS literature pertinent to this topic. Previous research on non-laser-based plasma literature, and the resulting knowledge, is also emphasized. The aim is, on one hand, to make the readers aware of such knowledge and on the other hand to trigger the interest of the LIBS community, as well as the larger analytical plasma community, in attempting some diagnostic approaches that have not yet been fully exploited in LIBS.

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“…[23][24][25] The number and charge states of ions produced by laser ablation depend on the energy and the power density of the ablation laser. In the current measurement, the fundamental 1.06 m laser emission of a Q-switched Nd:YAG laser is used for the ablation.…”

Section: A the Ion Sourcementioning

confidence: 99%

Reflection time-of-flight mass spectrometer for charge-transfer cross section measurements

Wang

Kwong

1997

Review of Scientific Instruments

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A new method is described that combines the production of ions by laser ablation with a reflection time-of-flight mass spectrometer for charge-transfer cross section measurements. This method allows a specific charge-transfer channel of an ion-neutral pair to be measured at energies of about 0.1 keV/amu. The metastable state ion fraction in the laser ablation ion beam is shown to be negligible. The charge-transfer cross section is determined by measuring the intensity ratio of the product ions to the parent ions after the charge-transfer reactions occur in the reflection drift tube. Verification on the apparatus is demonstrated through investigation of a single electron charge transfer of ground state C 2ϩ ions and H 2 with the incident energy of C 2ϩ at 3045.6͑ϭ12.4͒ eV. Our measured cross section of 6.90(Ϯ0.78)ϫ10 Ϫ16 cm Ϫ2 is consistent with ground state measurements reported previously. Because of the versatility of the pulsed laser ablation ion source, this facility can be used to examine the cross sections of a variety of multiply charged ions from refractory or gaseous elements.

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Atomic lifetime measurements obtained by the use of laser ablation and selective excitation spectroscopy

Cited by 36 publications

References 17 publications

The elemental composition of the Sun

The elemental composition of the Sun

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Reflection time-of-flight mass spectrometer for charge-transfer cross section measurements

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