Time-of-flight study of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">H</mml:mi><mml:mn /><mml:mo>(</mml:mo><mml:mn>2</mml:mn><mml:mi>S</mml:mi><mml:mo>)</mml:mo><mml:mn /></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">D</mml:mi><mml:mn /><mml:mo>(</mml:mo><mml:mn>2</mml:mn><mml:mi>S</mml:mi><mml:mo>)</mml:mo><mml:mn /></mml:math>produced by electron impact on<mml:math xmlns:mml="ht

Ryan, S. R.; Spezeski, Joseph J.; Kálmán, Orsolya; Lamb, Willis E.; McIntyre, L.C.; Wing, William H.

doi:10.1103/physreva.19.2192

Cited by 23 publications

(7 citation statements)

References 19 publications

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“…Atoms with zero kinetic energy can be produced through optically allowed transitions which have large cross sections at threshold; if optically forbidden transitions are much more important, they would mask the optically allowed ones in most of the experiments except at threshold where their cross sections are small. Later studies by Czarnik and Fairchild(l02) and Ryan et al (105) showed pronounced structure in the energy distribution of the "slow" group of H(2s) atoms. The random thermal motion of the H2 target gas in previous studies had smeared out the fine structure in the H(2s) energy distribution.…”

Section: Metastable Fragmentsmentioning

confidence: 97%

“…The pre dissociation structures observed for HD were more prominent and were not as easily interpreted. Ryan et al (105) estimate for H2 that at 100-eV electron energy"" 58% of the "slow" H(2s) fragments results from direct dissociation of the B' state and ""42% result from predissociation of the D state via the B' state.…”

Section: Dissociation Of Molecules By Slow Electrons 295mentioning

confidence: 99%

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Dissociation of Molecules by Slow Electrons

Compton

Bardsley

1984

Electron-Molecule Collisions

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Section: Metastable Fragmentsmentioning

confidence: 97%

Section: Dissociation Of Molecules By Slow Electrons 295mentioning

confidence: 99%

Dissociation of Molecules by Slow Electrons

Compton

Bardsley

1984

Electron-Molecule Collisions

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“…3 and have a high energy cutoff near 1 eV. Ryan et al [5] pointed out that TOF techniques lose sensitivity as the energy approaches zero. Based upon this, the difference is significant.…”

mentioning

confidence: 99%

Kinetic Energy Distribution ofH(2p)Atoms from Dissociative Excitation ofH2

et al. 1995

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The kinetic energy distribution of H(2p) atoms resulting from electron impact dissociation of H2 has been measured for the first time with uv spectroscopy. A high resolution uv spectrometer was used for the measurement of the H Lyman-n emission line profiles at 20 and 100 eV electron impact energies. Analysis of the deconvolved 100 eV line profile reveals the existence of a narrow line peak and a broad pedestal base. Slow H(2p) atoms with peak energy near 80 meV produce the peak profile, which is nearly independent of impact energy. The wings of H Lyman-u arise from dissociative excitation of a series of doubly excited Q& and Q2 states, which define the core orbitals. The fast atom energy distribution peaks at 4 eV. PACS numbers: 34.80.Ht, 33.50.Dq The kinetic distribution of H(2s) atoms from dissociative excitation of H2 has been the subject of much published research [1 -7], particularly in the late 1960s through 1980. The kinetic energy distribution function of H(2p) atoms from dissociative excitation of Hz has not previously been measured. The cross section for this process is the largest of Hz dissociative excitation processes [8], and a study of this process is paramount for an understanding of dissociation of H2. There are expected to be two distinct maxima in the H(2p) kinetic energy distribution by analogy to results obtained from the distribution of H(2s) and H(nl) atoms, where n = 3, 4, and 5. A comparison of the H(2p) and H(2s) distributions is of fundamental importance in understanding the dynamics of the H2 dissociation process which can occur from singly excited or doubly excited states. The former lead to the "slow" component and the latter lead to the "fast" component. In the separated atom limit, nonadiabatic coupling of the nearly degenerate 2p and 2s states is expected to lead to crossover of the H(2p) and H(2s) fragments [9].For higher principal quantum numbers through n = 5, studies of H(nl) kinetic energy distribution function have been carried out for many years by Ogawa and co-workers [10 -13]. Their interferometric technique involves measurement of the Doppler line profile of Balmer-n, -P, and -y in the visible and near uv portion of the spectrum.The Balmer-u line profile, for example, shows a characteristic narrow central peak (-300 mA FWHM) and a broad wing ( -1.8 A FWHM). However, the Balmer-n line profile is three separate multiplets from H(3s, 3p, 3d) excited states. Balmer-n has not been measured with sufficient resolution to study the slow atom distribution. In this work a spectroscopic technique was employed using a 3-m high resolution vacuum ultraviolet (vuv) spectrometer. Since the Doppler wavelength shift is proportional to the emission line wavelength, 5 to 6 times narrower line profiles can be expected in the vuv, necessitating the use of fast Fourier transform (FFT) techniques to deconvolve line profiles. The H Lyman-n (L ) multiplet structure is simple enough to yield both the slow and fast atom distributions from the deconvolved line profile. Most measurements of H(2s)...

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“…It is worth to mention that a similar analysis was accomplished by Ryan et al [19] despite their low spectrum resolution. They used empirical gaussians in energy and considered all peaks with the same width, in opposition to our conclusion that the width of the peaks are a function of the energy (or TOF).…”

Section: Analysis Of Tof Spectra and The Origin Of The Slow H(2 2 S 1...mentioning

confidence: 69%

“…Furthermore, it was shown that the B 1 Σ + u mixes with the B 1 Σ + u [15,18] and with the D 1 Π u [15,19], which were recently recalculated by Glass-Maujean et al [20,21]. Their work shows that B 1 Σ + u is in fact the double well state B B 1 Σ + u .…”

Section: Analysis Of Tof Spectra and The Origin Of The Slow H(2 2 S 1...mentioning

confidence: 94%

Slow metastable H(22S1/2) from dissociation of cold H2 induced by electrons

et al. 2012

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We have produced slow metastable H(2 2 S 1/2 ) coming from the dissociation of cold H2 induced by electron collisions. The experiment consisted of a supersonic jet of H2 crossing electrons produced by a high intensity pulsed electron gun. The neutral fragments were detected through electric field induced Lyman-α radiation and their velocities were measured by time-of-flight (TOF) technique. The main characteristics of our experiment are the low molecular temperature, the long flight path and the small well defined collision and electric field regions. They give rise to precise velocity measurements and, consequently, to good spectra resolution. We have performed a careful analysis of the electron-molecule collision kinematical effects in order to identify which vibrational levels can be involved in the transition. Our results also explain the origin of the TOF peak widths. Relative probabilities to produce these levels have been deduced.

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Time-of-flight study ofH(2S)andD(2S)produced by electron impact on
S. R. Ryan
¹
,
Joseph J. Spezeski
²
,
Orsolya Kálmán
³

et al.

Cited by 23 publications

References 19 publications

Dissociation of Molecules by Slow Electrons

Dissociation of Molecules by Slow Electrons

Kinetic Energy Distribution ofH(2p)Atoms from Dissociative Excitation ofH2

Slow metastable H(22S1/2) from dissociation of cold H2 induced by electrons

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Time-of-flight study ofH(2S)andD(2S)produced by electron impact onS. R. Ryan1, Joseph J. Spezeski2, Orsolya Kálmán3 et al.

Cited by 23 publications

References 19 publications

Dissociation of Molecules by Slow Electrons

Dissociation of Molecules by Slow Electrons

Kinetic Energy Distribution ofH(2p)Atoms from Dissociative Excitation ofH2

Slow metastable H(22S1/2) from dissociation of cold H2 induced by electrons

Contact Info

Product

Resources

About

Time-of-flight study ofH(2S)andD(2S)produced by electron impact on
S. R. Ryan
¹
,
Joseph J. Spezeski
²
,
Orsolya Kálmán
³

et al.