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1.
J. Lecointre H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):331-345
Absolute cross sections for electron-impact single ionization, dissociative
excitation and dissociative ionization of the ethynyl radical ion
(C2D+)^+) have been measured for electron energies ranging from the
corresponding reaction thresholds to 2.5 keV. The animated crossed
electron-ion beam experiment is used and results have been obtained for the
production of C2D2+, C2+, C2+_2^+ , CD+, C+ and
D+. The maximum of the cross section for single ionization is found to
be (2.01 ± 0.02) × 10-17 cm2, at the incident electron
energy of 105 eV. Absolute total cross sections for the various singly
charged fragments production are observed to decrease by a factor of almost
three, from the largest cross-section measured for C+, over C2+_2^+
and CD+ down to that of D+. The maxima of the cross sections are
obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+,
(12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ±
0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+.
The smallest cross section is measured to
be (1.50 ± 0.04) × 10-18 cm2 for the production of the
doubly charged ion C2+. Individual contributions for dissociative
excitation and dissociative ionization are determined for each
singly-charged product. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. Kinetic
energy release distributions of dissociation fragments are seen to extend
from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for
CD+, 14.2 eV for C+ and 11.2 eV for D+ products. 相似文献
2.
A.M. Frolov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(8):1-11
Absolute cross sections for electron impact ionization and dissociation of OH+ and OD+ leading to the formation of the OH2+, O+, O2+, O3+ and D+ ions have been measured by applying the animated electron-ion beam method in the energy range from the respective reaction thresholds up to 2.5 keV. The maximum of the single ionization cross section is found to be (0.95? ± ?0.02) × 10?19 cm2 at 155 eV. The maximum total cross sections for O+ and D+ fragments production are observed to be (15.7? ± ?0.2) × 10?17 cm2 at 95 eV and (10.8? ± ?0.5) × 10?17 cm2 at 95 eV, respectively. The cross sections for O2+ and O3+ are much smaller, (5.37? ± ?0.04) × 10-18 cm2 at 135 eV and (7.95? ± ? 0.23) × 10-20 cm2 at 315 eV, respectively. The collected data are analyzed in details in order to determine separately the contributions of dissociative excitation and of dissociative ionization to the O+ and D+ fragments production. 相似文献
3.
H. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):85-94
Absolute cross-sections for electron-impact dissociative ionization of C2
H2+ and C2 D2+ to CH+, C+, C2+ , H+, CH2+
and C2D+ fragments are determined for electron energies ranging
from the corresponding threshold to 2.5 keV. Results obtained in a crossed
beams experiment are analyzed to estimate the contribution of dissociative
ionization to each fragment formation. The dissociative ionization cross
sections are seen to decrease for more than an order of magnitude, from
CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19±
0.16) × 10-17 cm2, C2D+ (3.94±0.38) ×
10-17 cm2, C2+ (3.82±0.15) × 10-17 cm2
and H+ (3.37±0.21) × 10-17 cm2 to CH2+
(2.66±0.14) × 10-18 cm2. Kinetic energy release
distributions of fragment ions are also determined from the analysis of the
product velocity distribution. Cross section values, threshold energies and
kinetic energies are compared with the data available from the literature.
Conforming to the scheme used in the study of the dissociative excitation of
C2H2+
( C2 D2+ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in
a format suitable for their implementation in plasma simulation codes. 相似文献
4.
J. Lecointre D. S. Belic J. J. Jureta R. Janev P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(3):265-278
Absolute cross sections for electron-impact dissociative excitation and
ionization of CD+
4 leading to formation of ionic products (CD2+
4, CD+
3, CD+
2, CD+, C+, D+
3, D+
2, and D+) have been measured. The animated crossed-beams
method is applied in the energy range from the reaction threshold up to 2.5 keV. Around 100 eV, the maximum cross sections
are found to be (3.8±0.2) ×10-19 cm2,
cm2,
(7.1±0.8) ×10-17 cm2, (9.0±0.8) ×
10-17 cm2 and (3.7±0.4) ×10-17 cm2 for the
heavy carbonaceous ions CD2+
4, CD+
3, CD+
2, CD+ and C+ respectively. For the light fragments, D+
3, D+
2, and D+, the cross sections around the maximum are
found to be (5.0±0.6) ×10-19 cm2, (1.7±
0.2) ×10-17 cm2 and (10.6±1.0) ×10-17 cm2, respectively. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. The analysis
of ionic product velocity distributions allows determination of the kinetic
energy release distributions which are seen to extend from 0 to 9 eV for
heavy fragments, and up to 14 eV for light ones. The comparison of present
energy thresholds and kinetic energy release with available published data
gives information about states contributing to the observed processes.
Individual contributions for dissociative excitation and dissociative
ionization are determined for each detected product. A complete database
including cross sections and energies is compiled for use in fusion
application. 相似文献
5.
Yu. B. Burkatovskaya V. M. Bystritsky G. N. Dudkin A. R. Krylov A. S. Lysakov S. Gazi J. Huran B. A. Nechaev V. N. Padalko A. B. Sadovsky Yu. G. Tuleushev M. Filipowicz A. V. Philippov 《Physics of Particles and Nuclei Letters》2016,13(2):190-197
The cross section of the reaction D(4He, γ)6Li with titanium and zirconium deuterides as targets is measured for incident 4He+ ion energies of 30 and 36 keV, respectively. The ion beam is generated by a Hall pulsed plasma accelerator. For the first time, upper limits on the cross section of the reaction D(4He, γ)6Li at ultralow energies are imposed (at 90% confidence level): σ ≤ 1.2 × 10?35 cm2 for the TiD2 target and E(4He+) = 30 keV, and σ ≤ 7 × 10?36 cm2 for the ZrD2 target and E(4He+) = 36 keV 相似文献
6.
H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):75-83
Absolute cross-sections for electron-impact ionization and dissociation of
C2H2+ and C2D2+ have been measured for electron energies
ranging from the corresponding thresholds up to 2.5 keV. The animated
crossed beams experiment has been used. Light as well as heavy fragment ions
that are produced from the ionization and the dissociation of the target
have been detected for the first time. The maximum of the cross-section for
single ionization is found to be (5.56 ± 0.03)× 10-17 cm2 around 140 eV. Cross-sections for dissociation of C2
H2+ (C2D2+) to ionic products are seen to decrease for two orders
of magnitude, from C2D+ (12.6 ± 0.3) × 10-17 cm2 over CH+(9.55 ± 0.06) × 10-17 cm2,
C+ (6.66 ± 0.05) × 10-17 cm2, C2+ (5.36 ± 0.27) × 10-17 cm2, H+ (4.73 ±
0.29) × 10-17 cm2 and CH2+ (4.56 ± 0.27) × 10-18 cm2 to H2+ (5.68 ± 0.49) ×
10-19 cm2. Absolute
cross-sections and threshold energies have been compared with the scarce
data available in the literature. 相似文献
7.
Theodore E. Madey 《Surface science》1973,36(1):281-294
Measurements of both the absolute sticking probability near normal incidence and the coverage of H2 adsorbed on W(100) at ~ 300K have been made using a precision gas dosing system; a known fraction of the molecules entering the vacuum chamber struck the sample crystal before reaching a mass spectrometer detector. The initial sticking probability S0 for H2/W(100) is 0.51 ± 0.03; the hydrogen coverage extrapolated to S = 0 is 2.0 × 1015 atoms cm?2. The initial sticking probability S0 for D2/W(100) is 0.57 ± 0.03; the isotope effect for sticking probability is smaller than previously reported. Electron stimulated desorption (ESD) studies reveal that the low coverage β2 hydrogen state on W(100) yields H+ ions upon bombardment by 100 eV electrons; the ion desorption cross section is ~ 1.8 × 10?23 cm2. The H+ ion cross section at saturation hydrogen coverage when the β1 state is fully populated is ? 10?25 cm2. An isotope effect in electron stimulated desorption of H+ and D+ has been found. The H+ ion yield is ? 100 × greater than the D+ ion yield, in agreement with theory. 相似文献
8.
J. Lecointre D. S. Belic J. J. Jureta R. K. Janev P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):569-580
Absolute cross-sections have been measured for electron-impact dissociative
excitation and ionization of CD2+ leading to
formation of CD22+, CD+, C+,
D2+ and D+. The animated crossed-beams method
is applied in the energy range from the reaction threshold up to 2.5 keV.
The maximum total cross-sections are found to be (1.2±0.1)×10-17 cm2, (6.1±0.7)×10-17 cm2, (6.4±0.7)×10-17 cm2, (26.3±3.8)×10-19 cm2 and (14.9±1.4)×10-17 cm2 for
CD22+, CD+, C+,
D2+ and D+ respectively. Individual
contributions for dissociative excitation and dissociative ionization are
determined for each singly-charged product, which are of significant
interest in fusion plasma edge modelling and diagnostics. Conforming to the
scheme recently applied in the CD4+ and in the
CD3+ articles, the cross-sections are presented in
closed analytic forms convenient for implementation in plasma simulation
codes. Kinetic-energy-release distributions are determined for each ionic
fragment at selected electron energies. 相似文献
9.
J.P. Merrison H. Bluhme M. Charlton H. Knudsen M.R. Poulsen 《Hyperfine Interactions》1997,109(1-4):313-321
In support of the positronium based reaction scheme for antihydrogen formation an experiment has been performed which has
demonstrated hydrogen formation following proton impact on positronium. The cross section has been experimentally determined
at proton energies of 11.3 keV, 13.3 keV and 15.8 keV, values of σH = 26(±9), 7.8(±2.3) and 7.6(± 4.4) × 10−16 cm2 were obtained. The determination is in reasonable agreement with several recent calculations of the cross section and provides
a well characterised process for antihydrogen formation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
J. Lecointre D. S. Belic S. Cherkani-Hassani P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(3):441-448
Absolute cross sections for electron impact dissociation of ND+ leading to the formation of D+ have been measured by applying the animated electron-ion beam method in the energy range from the reaction threshold up to
2.5 keV. The maximum inclusive cross section is observed to be (16.8 ± 0.8) × 10−17 cm2 at the electron energy of 65.1 eV. The appearance energy for the D+ production is measured to be (4.0 ± 0.5) eV. Collected data are analyzed in details by means of an original procedure in
order to determine separately the contributions of dissociative channels. A specific Monte Carlo modeling has been developed,
which is proven to reconstruct adequately the dissociative ionization cross section. The present energy thresholds provide
information about the ground and excited states of the molecular ion, as well as about the possible population of the vibrational
levels. The reaction D2(v) + N+ (or H2(v) + N+) is a probable source for that population and it constitutes the first step of the molecular activated processes, so the
corresponding chain of reactions has to be considered to study the chemistry of plasma sources. 相似文献
11.
Jiandong Zhang Jiangtao Zhao Weilin Jiang Xingcai Guan Haibo Peng Zihua Zhu 《辐射效应与固体损伤》2013,168(11-12):1027-1036
ABSTRACTTungsten (W) has been regarded as one of the most promising plasma facing materials (PFMs) in fusion reactors. The formation of bubbles and blisters during hydrogen (H) irradiation will affect the properties of W. The dependence of implantation conditions, such as fluence and energy, is therefore of great interest. In this work, polycrystalline tungsten samples were separated into two groups for study. The thick samples were implanted by 18?keV H3+ ions to fluences of 1?×?1018, 1?×?1019 and 1?×?1020 H+/cm2, respectively. Another thick sample was also implanted by 80?keV H2+ ions to a fluence of 2?×?1017 H+/cm2 for comparison. Moreover, the thin samples were implanted by 18?keV H3+ ions to fluences of 9.38?×?1016, 1.88?×?1017 and 5.63?×?1017 H+/cm2, respectively. Focused ion beam (FIB) combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for micro-structure analysis, while time-of-flight ion mass spectrometry (ToF-SIMS) was used to characterize the H depth profile. It is indicated that bubbles and blisters could form successively with increasing H+ fluence. H bubbles are formed at a fluence of ~5.63?×?1017 H+/cm2, and H blisters are formed at ~1?×?1019 H+/cm2 for 18?keV H3+ implantation. On the other hand, 80?keV H2+ ions can create more trapping sites in a shallow projected range, and thus enhancing the blisters formation with a relatively lower fluence of 2?×?1017?H+/cm2. The crack-like microstructures beneath the blisters are also observed and prefer to form on the deep side of the implanted range. 相似文献
12.
The charge exchange and excitation cross sections at collisions of alphas with O4+(1s 22s 2) impurity atoms in a hot plasma for striking energies E c varying from 20 keV to 2 MeV are determined for the first time. The cross sections are calculated using the method of close-coupling equations with 13 singlet four-electron quasi-molecular states taken as a basis. The partial cross sections of charge transfer to the 1s, 2s, and 2p states of a He+ ion and for O4+(1s 22s 2) → O4+(1s 22lnl’) (n = 2, 3) electronic excitation of an oxygen ion are found. The maximal value of the charge exchange total cross section roughly equals 2.2 × 10?16 cm2 at E c ≈ 0.7 MeV. The excitation total cross section has a maximum of ≈ 7.7 × 10?16 cm2 at E c ≈ 80 keV for single-electron excitation and ≈6.5 × 10?16 cm2 at E c ≈ 0.7 MeV for two-electron excitation. 相似文献
13.
J.?Lecointre D. S.?Belic J. J.?Jureta R. K.?Janev P.?Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):557
Absolute cross-sections have been measured for electron-impact dissociativeexcitation and ionization of CD 2 + leading toformation of CD 2 2+ , CD+, C+,D 2 + and D+. The animated crossed-beams methodis applied in the energy range from the reaction threshold up to 2.5 keV.The maximum total cross-sections are found to be (1.2±0.1)×10-17 cm2, (6.1±0.7)×10-17 cm2, (6.4±0.7)×10-17 cm2, (26.3±3.8)×10-19 cm2 and (14.9±1.4)×10-17 cm2 forCD 2 2+ , CD+, C+,D 2 + and D+ respectively. Individualcontributions for dissociative excitation and dissociative ionization aredetermined for each singly-charged product, which are of significantinterest in fusion plasma edge modelling and diagnostics. Conforming to thescheme recently applied in the CD 4 + and in theCD 3 + articles, the cross-sections are presented inclosed analytic forms convenient for implementation in plasma simulationcodes. Kinetic-energy-release distributions are determined for each ionicfragment at selected electron energies. 相似文献
14.
F. Štěrba 《Czechoslovak Journal of Physics》1968,18(7):900-909
The ground state rotational bands in the odd isotopes of uranium U 233 and U 235, were studied by the inelastic scattering of 13.1 MeV deuterons. Seven members of these bands were seen in both nuclei. By fitting the experimental energies of the levels to the relation E(I)= =AI(I+1)+B[I(I+1)]2, the parametersA andB were determined. Their values and the upper limits of the quadrupole reduced transition probabilities determined from the cross sections were: U 233:A=(5.93±0.10)keV,B=(?0.002±0.001)keV,B(E2,5/2→7/2)= =(6.51±0.66)×10?48 e2 cm4,B(E2,5/2→9/2)=(2.80±0.37) X 10?48 e2 cm4. U 235:A=(5.36±0.04)keV,B=(?0.0017±0.0004) keV,B(E2,7/2→9/2)=(8.05±0.71) × × 10?48 e2 cm4,B(E2,7/2→11/2)=(2.17±0.39) X 10?48 e2 cm4. 相似文献
15.
Coulomb excitation studies have been performed to measure transition probabilities of collective quadrupole vibrational states in 180Hf. The I = 2 level of the Kπ = 2+ collective γ-band is established at 1200.5 keV with B(E2)exc = (11.0 ± 1.1) × 10?50e2 · cm4 (3.6 ± 0.4 s.p.u.). The angular distribution of the de-exciting γ-rays from this level yields δ = 9.6+22?5.8 or, less likely, 0.7 ± 0.2 for the 1107.2 keV 2γ+ → 2g+ transition. The B(E2)exc for any KπI = 0+2 stateorother 2+ states up to 1500 keV is less than 5 × 10?51e2 · cm4 (< 0.2. s.p.u.). 相似文献
16.
R. L. Aggarwal L. W. Farrar E. D. Diebold D. L. Polla 《Journal of Raman spectroscopy : JRS》2009,40(9):1331-1333
The absolute Raman scattering cross section (σRS) for the 1584‐cm−1 band of benzenethiol at 897 nm (1.383 eV) has been measured to be 8.9 ± 1.8 × 10−30 cm2 using a 785‐nm pump laser. A temperature‐controlled, small‐cavity blackbody source was used to calibrate the signal output of the Raman spectrometer. We also measured the absolute surface‐enhanced Raman scattering cross section (σSERS) of benzenethiol adsorbed onto a silver‐coated, femtosecond laser‐nanostructured substrate. Using the measured values of 8.9 ± 1.8 × 10−30 and 6.6 ± 1.3 × 10−24 cm2 for σRS and σSERS respectively, we calculate an average cross‐section enhancement factor (EF) of 0.8 ± 0.3 × 106. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
Cross sections have been measured for emission of the 2nd positive system of N2 and the 1st negative system of N+2 by electron excitation. The electron energy ranged from the threshold to 400 eV. To obtain absolute values, comparison with the emission cross section of the 51S He level has been used.The results for the (0, 2) band of the 2nd positive system and for the (0, 1) band of the 1st negative system are (2.87 ± 0.40) × 10-18 and (5.35 ± 0.5) × 10-18cm2, respectively, at the peak. The cross sections are given for 23 bands of the 1st negative systems.Use of the (0, 1) band of the 1st negative system is proposed for reference in obtaining absolute values. 相似文献
18.
《Physics letters. A》1999,251(5):336-339
The structural and electrical characteristics of H+-implanted SrBi2Ta2O9 (SBT) ferroelectric thin films were investigated by X-ray diffraction analysis and electrical measurements. 25 keV H+ with doses ranging from 1 × 1014/cm2 to 3 × 1015/cm2 were implanted into the Sol-Gel prepared SBT ferroelectric thin films. The X-ray diffraction patterns of SBT films show that no difference appears in the crystalline structure of H+-implanted SBT films compared with unimplanted films. Ferroelectric properties measurements indicate that both remnant polarization and the coercive electric field of H+-implanted SBT films decrease with increasing the implantation dose. The disappearance of ferroelectricity was found in the H+-implanted SBT films up to a dose of 3 × 1015/cm2. The leakage current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the H+-implanted SBT films were also discussed before and after a recovery process. 相似文献
19.
B. Esposito F. Felicetti A. Marini I. Peruzzi M. Piccolo F. Ronga A. Nigro F. Vanoli D. Bisello M. Nigro L. Pescara P. Sartori R. Bernabei P. Monacelli G. Piano Mortari L. Paoluzi F. Sebastiani 《Physics letters. [Part B]》1977,67(2):239-242
We present results for the total cross section of e+e? annihilation into two hadrons at 1.6 GeV: σππ = σKK = (1.8 ± 1.1) × 10-33 cm2.From these values we obtain the time-like electromagnetic form factors these mesons: |Fπ|2 = 0.24 ± 0.14 and |FK|2 = 0.46 ± 0.26. 相似文献
20.
H. Zacharias R. Schmiedl K. H. Welge 《Applied Physics A: Materials Science & Processing》1980,21(2):127-133
State and isotope selective two-step photoionization of NO with mass spectroscopic ion detection has been demonstrated and
investigated. Using saturation condition the photoionization cross section for a single rotational level of the intermediate
state, No(A
2Σ+, ν′=0), has been measured: σi=(7.0±0.9) X 10−19 cm2. The charge transfer15NO++14NO→15NO+14NO+ has been observed and investigated, yielding a cross section of the order of 13×10−16 cm2, consistent with recent measurements at about 1 eV. 相似文献