Die Auger-Spektren derL 2- undL 3-Schale von Argon

TheL ₂ MM andL ₃ MM-Auger spectra of gaseous argon have been investigated with an electrostatic spectrometer with energy resolution of 0.17%. The ionization in theL ₂ andL ₃ shell was caused by electron impact. It was possible to separate allL ₂ MM andL ₃ MM lines except the components of transitions to triplet final states. The experimental relative intensities of transitions within theL ₂ M _2,3 M _2,3 andL ₃ M _2,3 M _2,3 groups agree well with theoretical values, calculated byRubenstein, whereas the relative intensities of transitions of the groupsL ₂ M ₁ M ₁,L ₃ M ₁ M ₁,L ₂ M ₁ M _2,3 andL ₃ M ₁ M _2,3 differ systematically from theoretical values.     

Messungen zu den Vibrations- und Zweiquasiteilchenzuständen in172Yb

The Coster-Kronig and Auger spectrum of theL ₁ shell of gaseous argon has been investigated with an electrostatical spectrometer. The ionization in theL ₁ shell of argon was caused by electron impact. Absolute energies and relative intensities of all the Coster-Kronig and Auger transitions have been determined. The relative intensities of transitions within the groupsL ₁ L _{2, 3} M ₁,L ₁ L _{2, 3} M _{2, 3} andL ₁ MM agree fairly well with the theoretical values, calculated byRubenstein for extreme Russel-Saunders coupling, if intermediate coupling theory is used properly. Via the widthγ(L ₁) of theL ₁ level of argon, found in this experiment to be (1.84±0.2) eV, the following absolute group transition probabilities were determined (in units of 10¹⁴ sec^?1):W(L₁ L _{2, 3} M ₁)=(5.5±1.0),W(L₁ L _{2, 3} M _{2, 3})=(20.8±2.8),W(L₁ MM)=(1.44±0.16). The theoretical values are 21.0, 20.4 and 1.27. The possible reason for the large discrepancy between the experimental and theoretical value ofW(L₁ L _{2, 3} M ₁) is the use of the incorrect value of 287 eV for the binding energyE(L₁) byRubenstein. From the energies of theL ₁ MM transitions this value has been determined to beE(L₁)=(326.5±0.5) eV. This is the first direct measurement ofE(L₁) of argon.     

Inner-shell ionization by relativistic electron impact

K-, L andM-shell ionization cross sections have been measured for 23 elements, 12≦Z≦92, after bombardment with relativistic electrons, 15≦E ₀65MeV, by means of high resolution semiconductor detectors and a recently developed gas-scintillation proportional counter. For constant electron bombarding energyE ₀ the ionization cross sections follow a power law dependence,σ∽Z ^?α, and forE ₀=50MeV we deducedα =2.45±0.02 for theK shell andα=3.00 ±0.09 for theL shell. The observedZ dependence exhibits significant systematic deviations from theoretical predictions which exceed the experimental values up to 15 % at lowZ elements for theK shell and on the average about 11% for theL andM shell. The same behaviour of too low experimental values, i.e. an overestimation by the theory, is observed for the energy dependence of the cross sections for all shells. A scaling behaviour describing theZ andE ₀ dependence for allK-, L andM-shell data points is observed which also predicts the experimental values by other groups at lower and higher energies correctly. The comparsion of the measuredLΒ/Lα, andLγ/Lα intensity ratios for highZ elements with the values obtained by other groups in the energy range 0.3≦E₀≦1,000 MeV exhibits an increase with bombarding energy that cannot merely be explained by the energy dependence of the subshellionization cross sections for theL shell. An attempt to explain this effect with the change of the Coster-Kronig transition probability is described.     

L-subshell fluorescence and coster-kronig yields atZ=92 and the decay of235Np

TheK andL x-rays emitted in the decay of²³⁵Np have been studied with high resolution Ge(HP) and Si(Li) detectors in coincidence, in order to obtain theL ₂ andL ₃ subshell fluorescence and Coster-Kronig yields atZ=92. The results are:v ₂=0.630±0.036, ω₂=0.560±0.033,f ₂₃=0.147±0.010, and ω₃=0.481±0.029. Results for theL ₁ subshell were derived from singles spectra, by assuming a value off ₁₃ of 0.67, and are:v ₁=0.54±0.04, ω₁=0.21±0.04, andf ₁₂<0.07. With the same assumption, theL ₁/K electron capture ratio and decay energyQ _ec for²³⁵Np were found to be 29.0±3.6 and 123.6±0.7 keV, respectively. RelativeL x-ray intensities forZ=92 also were measured and are compared with the theory of Scofield and with recent diffraction experiments. Electron ejection from theL shell during²³⁵Np decay has been studied byL x-ray-L x-ray coincidences and found to occur with a probability of (1.3±1.0) × 10^?4 per disintegration.     

Internal conversion studies of the 114 keV transition in175Lu

Measurements of the conversion line intensities, the directional correlation and the conversion probability for the 114 keVM1+E2 transition in¹⁷⁵Lu are reported. TheE2 admixture, determined from relativeK andL intensities, is (19.2±0.2)%. The theoreticalL _I internal conversion coefficient is found to be about 8% too low relative theK,L _II andL _III conversion coefficients.     

Inner-Shell X-ray production in adiabatic iodine-Z 2 collisions,withZ 1+Z 2≧100

K-, L- andM-x ray production cross sections for the molecular excitation regime in heavy ion-atom collisions (Z ₁+Z ₂≧100) are reported for the projectile velocity range 1.3–3.7 a.u. Outer-shell vacancy configurations of the collision partners having experienced inner shell vacancy creating collisions are deduced from the x-ray spectra. The influence of outer shell vacancy occupation on fluorescence yields is discussed and vacancy production cross sections are derived from x-ray production cross sections.     

Calculations of electron screening in muonic atoms

The electron screening in mounic atoms (O, Al, Fe, In, Ho, Au, Th) has been calculated forp _3/2,d _5/2 andf _7/2 levels withn _µ≦30 and for circular orbits withn _µ≦12 using a relativistic Dirac-Fock program. Simple empirical formulae are presented which can be employed to calculate the screening corrections for all elements fromZ=8 toZ=90, forp _3/2,d _5/2 andf _7/2 muons up ton _µ=30 Screening corrections are also given for electron configurations with holes in theK andL ₃ shell.     

An experimental investigation of the onset of theL 2-L 3 M 4 andL 2-L 3 M 5 Coster-Kronig transitions forZ>90

L-M coincidence measurements were made on x rays from the radioactive decays of ₉₆ ²⁴⁴ Cm, ₉₄ ²³⁸ Pu, and ₉₂ ²³² U. The observation ofM x rays in coincidence with theL ₃ N _{4, 5} transition indicates that the onset of theL ₂-L ₃ M ₅ Coster-Kronig transition takes place atZ=91 or 92. The measured ratio of theM x-ray counting rates, coincident with theL ₃ N _{4, 5} andL ₂ M ₄ transitions, establishes that both theL ₂-L ₃ M ₄ and theL ₂-L ₃ M ₅ transitions are energetically possible forZ≧94, but the results do not rule out the possibility that these transitions begin as low asZ=92. The measurement ofL-M x-ray coincidences, together with relative Coster-Kronig electron intensities from theory or experiment, provides a new way to measure the totalL ₂-L ₃ Coster-Kronig transition probability,f ₂₃, at highZ for radioactive sources where the primary vacancies are created primarily in theL ₂ andL ₃ subshells. The present result atZ=94 indicates that the theoretical calculations of McGuire of the relative partial Coster-Kronig transition rates forL ₂-L ₃ M _4,5 are accurate to within 10 percent.     

DasKLL- Auger-Spektrum von Chlor

TheKLL Auger spectrum of chlorine in CCl₄ has been investigated with an electrostatic energy analyzer. The ionization in theK shell of chlorine was caused by electron impact. Absolute energies and relative intensities of transitionsKL ₁ L ₁(¹ S,KL ₁ L _2,3(¹ P),KL ₁ L _2,3(³ P) andKL _2,3 L _2,3(¹ D) have been determined. Via the width of theK level of chlorine also experimental values of absolute transition probabilities have been calculated. While the relative intensities deviate strongly from theoretical values, the absolute transition probabilities agree better with theoretical values, especially with those calculated byRubenstein. — In an appendix the natural line widths of theKLL components of argon have been calculated theoretically.     

L 2 andL 3 subshell fluorescence and Coster-Kronig yields forZ=96 from the decay of249Cf

TheL ₂ andL ₃ subshell fluorescence and Coster-Kronig yields forZ=96 have been measured by theK-L x-ray coincidence method with high resolution Si(Li) and Ge(Li) x-ray detectors. The results ν₂=0.650±0.036, ω₂=0.552±0.032, ω₃=0.515±0.034, andf ₂₃=0.188±0.019 agree fairly well with theory. New measurements of theL x-ray singles spectra of²⁴⁴Cm and²³⁸Pu with a high resolution Si(Li) detector permitted reevaluation of the values of ω₂ andf ₂₃ forZ=92 and 94 reported by Byrneet al. The revised values atZ=92 are ω₂=0.529±0.035 andf ₂₃=0.23±0.12, and atZ=94, ω₂=0.523±0.023 andf ₂₃=0.24±0.08. These revised values are in much better agreement with theory and with current experiments.     

L-subshell ionization cross sections for Au,Pb, and Bi by 60–600 keV electron impact

TheL ₁-,L ₂- andL ₃-subshell ionization cross sections of Au, Pb and Bi by 60–600 keV electron impact have been determined from the measured x-ray production cross sections. The experimental results have been compared with the relativistic PWBA, the Binary Encounter Approximation (BEA) and the Kolbenstvedt Approximation (KA) calculations. These calculations, especially the relativistic PWBA, give good agreement with the experimental data for theL ₃-subshell. For theL ₁- andL ₂-subshells there are some deviations and these can explain the disagreement observed for theL _α/L _χ- andL _γ/L _χ intensity ratios.     

Many-body effects in l2mm auger electron spectra of Ge(CH3)4 excited by Mg Kα X-rays

The Ge:L₂MM Auger electron spectra excited by Mg Kα X-rays from Ge(CH₃)₄ free molecules have been compared with the corresponding spectra excited by Al Kα X-rays. The Al Kα excited spectra have characteristic features of the diagram Auger transitions, because the excitation energy is far above the L₂ ionization threshold. The energy of Mg Kα photons is 1.21 eV below the Ge:L₂ ionization threshold and thus the Mg Kα excited L₂MM Auger electron spectra indicate many-body effects, post collision interaction (PCI) effects and spectator Auger satellite structures. The L₂M_4,5M_4,5 type spectrum displays both these features but the L₂M_2,3M_4,5 type spectrum has only a spectator Auger satellite structure, because the (3p⁻¹3d⁻¹nl) final state interferes with the (3s) hole state.     

TheL- andK- Auger spectra of tellurium

TheL- andK- Auger spectra of tellurium (Z=52) were studied from the electron capture decay of¹²⁵I. The measured relativeL- Auger transition intensities are not in agreement with the theoretical intensities of Asaad for silver (Z=47). The measured relativeKLL intensities are in agreement with those ofGraham et al. Relative intensities are given for theKL Y spectrum. TheKL Y/KLL ratio was measured to be 0.44 ± 0.02 in good agreement with the theoretical value given byWapstra.K/L andL subshell conversion ratios are given for the 35 keV nuclear transition in¹²⁵Te.     

TheL 1 subshell fluorescence and Coster-Kronig yields forZ=96

High resolution Si(Li)-Si(Li) and Si(Li)-Ge(Li) detector arrangements have been used to studyL x-ray spectra in coincidence withL-shell internal conversion electrons, gamma rays, andK x-rays emitted in²⁴⁹Cf decay. TheL ₁ subshell fluorescence and Coster-Kronig yields determined forZ=96 from these spectra are ω₁=0.25±0.06,f ₁₂≦0.10, andf ₁₃=0.69 ±0.08. The presence of theL ₁-L ₃ radiative transition is also further confirmed in this work.     

Relative internal conversion electron intensities of the 113 keV transition in177Hf

The intensities of the internal conversion lines of the 113 keVM1 +E2 transition in¹⁷⁷Hf have been measured. From comparison with theoretical conversion coefficients the transition has been found to be (95.2 ± 0.5)%E2 corresponding to ¦δ¦=4.5 ± 0.3. The theoreticalL _I andM _I conversion coefficients used in the comparison have been increased by 5% according to the result that for pureE2 transitions in the deformed region theL _I/L _II,L _I/L _III,M _I/M _II, andM _I/M _III theoretical ratios are too low (～5%). Moreover, the present result indicates that theL _II/L _III andM _II/M _III ratios obtained from the tabulations by Hager and Seltzer and from the computer program by Pauli are too high (1–2%).     

Anomalous Auger-electron spectra of metallic calcium

A1Kα-excited L_{2, 3}MM and L_{2, 3}MV Auger-electron spectra of Ca have been measured in ultrahigh vacuum from a metallic sample evaporated onto an Ag substrate. An interpretation of the spectra is made by applying a line-fitting procedure. The lineshape and the solid-state—free-atom kinetic-energy shift are also studied. The extrinsic loss structure in the L_{2, 3}MM Auger-electron emission is found to be similar to that in 2p photoelectron emission. Spin—density-functional (SDF) calculations for the singularity index describing the intrinsic lineshape give a value of ～ 0.35 for both processes. Thus the experimental 2p_3/2 photoelectron line broadened from 1.2 to ～ 5 eV FWHM has been used as a standard line in the line fitting of the L_{2, 3}MM transitions. The term splitting of the L_{2, 3}M_{2, 3}M_{2, 3} transition is larger than in the corresponding free-atom spectrum. This result is also supported by the SDF calculations. The L_{2, 3}M_{2, 3}V spectrum is anomalously sharp, probably both because of the structure of the local density of states at the site of the core-ionized atom and because of differences in the transition probabilities into the different parts of the band. The experimental solid-state shift is 20.3 eV for the L_{2, 3}M_2,3M_{2, 3}:¹D transition, and the binding-energy shifts are 8.3 and 6.1 eV for the 2p and 3p levels, respectively. The SDF shifts for the above transitions are 19.9 (configurational average), 9.4 and 8.0 eV, consecutively, in agreement with the experimental values. The calculations also show a localized d-type (atomic-like) structure for the screening of the initial- and final-state core hole (s). This is the origin of the large values of both the singularity index and the solid-state shift.     

On the octupole excitation in236U

Measurements of theK,L _I,L _II andM _I conversion lines of the 687.7 keV transition in²³⁶U are evaluated within the electron penetration formalism. The spin-parity assignment of the octupole bandhead is found to be 1^? in accordance with reaction data, and an assignment of 2^? to the 687.7 keV state is ruled out. The penetration matrix element ∥η∥ has the value of 13.5 for theK-shell and increases slightly for higher main shells. An estimate of the anomalous amplitudes is compared with values reported for transitions in the odd even actinide nuclei. Furthermore electron conversion data for the 1^?→2⁺ and 1^?→4⁺ transitions are given. Radioactivity²³⁶U from²³⁵U(n,e ^?); measured: conversion electron decay; deduced: conversion coefficients fromK, L andM shells; evaluated: dynamic matrix elements.     

Decay studies of101m Rh and101g Rh

The level structure of¹⁰¹Ru has been investigated from the decays of^101m Rh and^101g Rh. For the gamma-ray measurements Ge(Li) detectors with effective volumes of 24 and 43 cm³ were used for singles and coincidence work, and several new transitions were observed. Conversion electron spectra from the^101m Rh decay were investigated with a 50 cm double-focussing beta spectrometer.K-conversion coefficients were determined by combining internal conversion and gamma-ray intensities. For the stronger transitions probable multipolarity assignments have been obtained from these coefficients and also fromK/L andL-subshell ratios. All transitions observed were fitted into a decay scheme, in which tentative spin-parity assignments of all states are given.     

Relative strengths of the competing multipoles in the K and L series x-ray spectra in theNR limit

For most of the transitions of theK andL series x-ray spectra the ratio of the contributions of the competing multipoles, δ², is independent of the radial matrix element in the non-relativistic limit. In the present paper calculations of δ² are made in the non-relativistic limit which give the relative strengths of the two closely competing electric and magnetic multipoles. The dominant mode in the emission processes of the transitions in theK andL series x-ray spectra has been assigned on the basis of these calculations.     

Decay of194Os andL 1 subshell yields atZ=77

The relative intensities of x rays and gammas emitted in the beta decay of¹⁹⁴Os are measured. No evidence for the feeding of a level at 83 keV in¹⁹⁴Ir is found. An upper limit of 1.7×10^?4 was set for theK shell internal ionization probability in the beta decay to the ground state of¹⁹⁴Ir. TheL-conversion coefficient of 43 keV transition is found to be 12.1 and the transition is mainly ofM1 type with an admixture of 1.3%E2 type. TheL ₁ subshell yields atZ=77 are determined to beω ₁=0.16±0.04,f ₁₂=0.11±0.04 andf ₁₃=0.37±0.03.