Measured lifetimes of excited levels in krypton II, xenon II and molecular hydrogen by the photon-photon delayed-coincidence technique

Mohamed, K.A.; King, G. C.

doi:10.1088/0022-3700/12/17/011

Cited by 24 publications

(6 citation statements)

References 33 publications

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“…The radiative lifetimes of a 3 Σ + g , v ′ vibronic states of H 2 have been studied in numerous works both experimentally [2,3,12,[36][37][38] and by ab initio calculations [1,5]. All available data are collected in Table III.…”

Section: Constants Of Elementary Processesmentioning

confidence: 99%

uv continuum emission and diagnostics of hydrogen-containing nonequilibrium plasmas

Lavrov

Melnikov

Käning³

et al. 1999

Phys. Rev. E

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For the first time the emission of the radiative dissociation continuum of the hydrogen molecule (a 3 Σ + g → b 3 Σ + u electronic transition) is proposed to be used as a source of information for the spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of excitation-deactivation kinetics, rate constants of various collisional and radiative transitions and fitting procedures made it possible to develop two new methods of diagnostics of: (1) the ground X 1 Σ + g state vibrational temperature T vib from the relative intensity distribution, and (2) the rate of electron impact dissociation (d[H 2 ]/dt) diss from the absolute intensity of the continuum. The known method of determination of T vib from relative intensities of Fulcher-α bands was seriously corrected and simplified due to the revision of d → a transition probabilities and cross sections of d ← X electron impact excitation. General considerations are illustrated with examples of experiments in pure hydrogen capillary-arc and H 2 +Ar microwave discharges. In pure H 2 plasma the values of T vib obtained by two independent methods are in rather good accordance (T vib =3000-5000 K). In the H 2 +Ar microwave plasma it was observed for the first time that the shape of the continuum depends on the ratio of the mixture components. Absorption measurements of the population of the 3s 2 3p 5 4s levels of Ar together with certain computer simulations showed that the Ar*→H 2 excitation transfer plays a significant role. In our typical conditions (power flux: 4 W cm −2 , pressure p = 0.5 mbar, H 2 :Ar=1:1) the following values were obtained for the microwave discharge: (d[H 2 ]/dt) diss ≈ 2.5 − 5 · 10 17 cm −3 s −1 . The contribution of the excitation transfer is about 10-30% of the total population of the a 3 Σ + g state.

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Section: Constants Of Elementary Processesmentioning

confidence: 99%

uv continuum emission and diagnostics of hydrogen-containing nonequilibrium plasmas

Lavrov

Melnikov

Käning³

et al. 1999

Phys. Rev. E

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“…1 " 5 The forbidden aspect of singlet to triplet transitions makes optical excitation of triplet levels from the ground state difficult. 6 The density of closely spaced levels with similar decay channels makes it difficult to use pulsed electron excitation as a source of excited molecules for lifetime measurements.…”

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confidence: 99%

Direct Lifetime Measurement of Laser-Excitedn=3Levels in Para-H2

Eyler

Pipkin

1981

Phys. Rev. Lett.

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This paper reports measurements of the lifetimes of fourteen levels in the 3s, 3d complex of para-H 2 by a delayed coincidence method. A collimated beam of metastable hydrogen molecules was selectively excited by light pulses from a cw dye laser and fluorescent radiation was detected by a vacuum ultraviolet photo multiplier. The observed lifetimes range from 11.1 to 48.8 nsec. Similar methods can be used to determine the structure and lifetimes in other excited states of H 2 and in a variety of other systems.

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“…A more general approach to coincident particle detection uses the detection of one particle as a time reference, and the detection times of the other particles are measured relative to this reference. 19,[41][42][43][44][45][46][47][48][49][50][51] Here, no joint and synchronized reference clock is required, which allows the use of continuous or quasi-continuous excitation sources additionally to pulsed sources.…”

Section: Articlementioning

confidence: 99%

Photon–electron coincidence experiments at synchrotron radiation facilities with arbitrary bunch modes

Ozga

Honisch

Schmidt

et al. 2021

Review of Scientific Instruments

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Measured lifetimes of excited levels in krypton II, xenon II and molecular hydrogen by the photon-photon delayed-coincidence technique

Cited by 24 publications

References 33 publications

uv continuum emission and diagnostics of hydrogen-containing nonequilibrium plasmas

uv continuum emission and diagnostics of hydrogen-containing nonequilibrium plasmas

Direct Lifetime Measurement of Laser-Excitedn=3Levels in Para-H2

Photon–electron coincidence experiments at synchrotron radiation facilities with arbitrary bunch modes

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