Precise measurement of the KLL and KLX Auger spectra of cadmium from the EC-decay of 111In

The KLL and KLX Auger spectra of Cd from the EC-decay of ¹¹¹In have been analyzed with the 7 eV instrumental resolution using a combined electrostatic spectrometer and a source prepared by a modified Langmuir–Blodgett method. Energies and relative intensities of all the nine well resolved KLL lines have been precisely determined. While the latter quantities were found to be in very good agreement with the relativistic intermediate coupling calculations, the former ones deviate from results of the widely used semi-empirical calculations especially in the case of the absolute energies. The predicted strong influence of the relativistic effects on the KL₁L₂(³P₀) transition intensity has been proved. Most of the main KLX Auger lines have been well separated and their complex structures have been observed. Accurate energies and intensities obtained for these lines have been compared with results of calculations. The intermediate coupling splitting of the KL₂L₂ and KL₃L₃ lines have been revealed. The KLX/KLL, KLN(O)/KLM, and KXY/KLL group intensity ratios have also been determined. A conclusion is made that further finer theoretical investigation on the complex interaction mechanism for two inner-shell vacancies is still very much needed.     

Energy and angular distributions of electrons emitted by direct double auger decay

We have observed the direct L(2,3)MMM double Auger transition after photoionization of the 2p shell of argon by angle-resolved electron-electron coincidence spectroscopy. The process is responsible for about 20% of the observed Auger electron intensity. In contrast to the normal Auger lines, the spectra in double Auger decay show a continuous intensity distribution. The energy and angular distributions of the emitted electrons allow one to obtain information on the electron correlations giving rise to the double Auger process as well as the symmetry of the associated two-electron continuum state.     

The decay of Se

The gamma-ray spectrum associated with the electron capture decay of ⁷⁵Se has been studied with Ge(Li) spectrometers. Coincidence spectra were taken with a Ge(Li)---Ge(Li) combination. The data do not support a recent report of several new gamma rays in the decay of ⁷⁵Se. Gamma-gamma angular correlation experiments were performed with a NaI(Tl)---Ge(Li) combination. The value obtained for δ(280 keV) is in excellent agreement with one recently reported value but in poor agreement with another. The ratio P_K/P_tot for the electron capture branch to the 401 keV level of ⁷⁵As has been determined, and the result agrees with previous experimental determinations.     

The decay of75Kr

The decay of the isotope⁷⁵Kr (T_1/2=4.5 ±0.3 m) has been studied using mass separated sources produced at the ISOLDE facility at CERN. A decay scheme is proposed based on gamma, positon, and conversion electron singles and coincidence measurements. The total decay energy was measured to be Q_EC=4.4 ± 0.2 MeV. The resulting spin-parity assignments and the absence of a 9/2⁺ isomeric state in⁷⁵Br are discussed.     

The range of energetic auger electrons in the electron-hole liquid in Ge

Some controversy has arisen as regards to the escape probability of Auger decay electrons from electron-hole drops. We present experimental and theoretical arguments which show that in fact most electrons do escape.     

The decay of75Ga to levels in75Ge

The decay of⁷⁵Ga has been investigated with Ge(Li) spectrometers. Energy and intensity determinations for 37 gamma rays have been performed. A level scheme for⁷⁵Ge was deduced, where 31 gamma transitions could be placed. Beta branch intensities were estimated from the measured gamma intensities. Spin and parity assignments for most of the levels were made in agreement with reaction and neutron capture studies. Half life of⁷⁵Ga was measured to be (130±6) sec and that of the 139.3 keV isomeric state in⁷⁵Ge to be (47.7±0.5) sec.     

The decay of 33 70 Se37

The decay of⁷⁰Se was studied using a 75 cm³ Ge(Li) detector, placed in an anti-compton shield, and a low-energy detector. Of the 36γ-rays observed 31 are placed in a levelscheme of⁷⁰As, based on coincidence- and sumrelations. Conversion electrons of two low energy transitions were observed in order to determine their multipolarity. The halflife is measured (41.1 min). Spins and parities of the excited levels were deduced and compared with shell model predictions and logft values of theEC/β ⁺ branches were calculated.     

The KLL Auger spectrum of neon from the EC-decay of Na

The low energy KLL Auger electrons of neon emitted after EC-decay of ²²Na have been investigated with a 4 eV instrumental resolution using an electrostatic spectrometer and a solid state radioactive source. This is the first experimental investigation of the KLL Auger spectrum of neon from the solid state. Relative intensities and energies of all resolved spectrum components were determined. Measured absolute energy of the dominant KL₂L₃(¹D) transition was found to be 824.5(19) eV, i.e. about 20 eV higher than that obtained in experiments with free Ne atoms. Within the experimental uncertainties, no influence of solid state effects on relative intensities of the KLL transitions was found.     

Experimental evidence of interatomic coulombic decay from the auger final states in argon dimers

Interatomic Coulombic decay (ICD) from an Auger-final dicationic state is observed in the Ar dimer. A 2p inner-shell vacancy created by photoionization is replaced with 3s and 3p vacancies via intra-atomic Auger decay. The Auger-final dicationic state is subject to ICD in which one of the 3p electrons in the same Ar atom fills the 3s vacancy while one of the 3p electrons from the neighboring Ar atom is emitted as an ICD electron. This ICD process is unambiguously identified by electron-ion-ion coincidence spectroscopy in which the kinetic energy of the ICD electron and the kinetic energy release between Ar+ and Ar2+ are measured in coincidence.     

Mirror decay of 75Sr

The β-decay of ⁷⁵Sr to its mirror nucleus ⁷⁵Rb was studied at the ISOLDE PSB facility at CERN by means of β-delayed γ and proton spectroscopy. The decay Q-value and β-delayed γ intensity were measured for the first time. These results, 10.60±0.22 MeV and 4.5^+1.9 _-0.7%, together with accurate measurements of the β-decay half-life and β-delayed proton branching ratio yielded the Gamow-Teller strength 0.35±0.05 for the mirror transition. Implications of the results on studies of deformation effects and on the path of the rapid proton capture process are discussed. Received: 26 September 2002 / Accepted: 30 October 2002 / Published online: 18 February 2003 RID="a" ID="a"e-mail: jussi.huikari@phys.jyu.lfi Communicated by D. Schwalm     

Weak localization of inelastically reflected electrons under auger emission conditions

A new type of weak localization of electrons emerging during electron emission is considered. It is manifested in singularities of the angular spectra of particles reflected inelastically from a solid and causing Auger ionization of the atoms. The orientational dependences in this case appear as a result of interference of two types of processes. In one case, an electron from the primary beam penetrates the solid, undergoes inelastic scattering, ionizes an atom, and is then scattered elastically through a large angle, after which it leaves the solid. In the other case, elastic scattering of an electron precedes its inelastic scattering due to the Auger ionization of an atom. The azimuthal angular dependences of currents created by inelastically reflected electrons contain information on new processes of weak localization of particles.     

The continuum orbital problem in the calculation of auger decay rates: Application to Ne

Summary Described here are new computational procedures which have been developed for obtaining the continuum orbital in Auger problems. A Lippmann-Schwinger (LS) equation is solved for the inner, atomic or molecular region and in the asymptotic region the LS orbital is matched with the eigenfunctions of the long-range Hamiltonian. A detailed analysis of the form of the continuum orbital for various decay states of the KLL Auger spectrum of the neon atom is presented. Decay rates are given for the Ne and compared with previous results and with experiments.

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Riassunto Si presenta una nuova tecnica per ottenere l'orbitale del continuo in problemi Auger. Essa consiste nella soluzione di un'equazione alla Lippmann-Schwinger (LS) per la regione atomica o molecolare e nel raccordo dell'orbitale cosí ottenuto con le autofunzioni dell'hamiltoniana contenente la parte asintotica del potenziale. Si effettua inoltre un'analisi dettagliata della forma dell'orbitale del continuo per vari possibili stati di decadimento Auger dell'atomo di Ne ionizzato nel guscio 1s e si interpreta lo spettro KLL di tale sistema in termini di energie di risonanza e velocitá di decadimento.

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Резюме В работе описываются новые вычислительные процедуры, которые были развиты для получения непрерывной орбитали в Оже-проблемах. Решается уравнение Липмана-Мвнгера для внутренней атомной или молекулярной области. В асимптотической области орбиталь Липмана-Швингера согласуется с собственными функциями Гамильтониана. В работе проводится подробный анализ формы непрерывной орбитали для различных возможных состояниЙ Оже-распада атома Ne. Приводятся интенсивности распада для Ne и сравниваются с предыдущими результатами и данными экспериментов.

     

Conversion electrons in the decay of191Os

Internal conversion electrons in the decay of¹⁹¹Os have been measured with a 30 cm double focusing spectrometer. The transition energies of (129.27±0·07) keV, 82.5 keV, (46.90±±0.06) keV and (41.76±0.02) keV are given together with the corresponding internal conversion line intensities. It was found that the mixture of the 129 keV transition was 87% M1+13% E2. The previously proposed decay scheme is supplemented by the 46.90 keV transition.The authors would like to thank to M. Vobecký and A. Matalka for preparing the electrodeposited sources.     

Multielectron spectroscopy: the xenon 4d hole double auger decay

A magnetic bottle spectrometer of the type recently developed by Eland et al. [Phys. Rev. Lett. 90, 053003 (2003).] has been implemented for use with synchrotron radiation, allowing multidimensional electron spectroscopy. Its application to the Xe 4d double Auger decay reveals all the energy pathways involved. The dominant path is a cascade process with a rapid (6 fs) ejection of a first Auger electron followed by the slower (>23 fs) emission of a second Auger electron. Weaker processes implying 3 electron processes are also revealed, namely, direct double Auger and associated Rydberg series.     

Double-electron capture of Se and the search for neutrinoless decay

Experimental results on the measurement of the double-electron capture (εε) decay process of ⁷⁴Se are described. This decay is particularly interesting, because ⁷⁴Se is almost degenerate to the second excited state at 1204 keV in the daughter nucleus ⁷⁴Ge. Such a degeneracy favors a neutrinoless decay because of the large phase-space suppression for a decay with two neutrinos. Subsequent de-excitation would generate a 2γ-ray cascade of 608 and 596 keV, whose coincident detection provides a unique signature for this particular εε process. The 2γ-ray cascade has been searched for by a HPGe γ-ray detector in coincidence with a NaI detector using 3 kg of natural selenium.     

On the influence of backscattered electrons on the lateral resolution in scanning auger microscopy

A definition of edge resolution is proposed, which is adapted to the pecularities of scanning Auger microscopy. Based on recent monte-Carlo computer simulations for scanning electron microscopy, the influence of backscattered electrons on the edge resolution is estimated for low-Z (Al) and high-Z materials (Au). The resolution is found to be of the order of 100nm and to be nearly independent of the atomic number of the sample.     

KLL auger and core level (1s and 2p) photoelectron shifts in a series of gaseous sulfur compounds

Core (1s and 2p) X-ray photoelectron shifts and KLL (¹D₂) Auger shifts for 22 sulfur compounds have been measured. The values have been correlated by means of atomic charge plus remote potential or central atom potential models. Either approach is equally effective tor binding energy correlations. The relaxation corrected and transition state models are in general superior to ground state models. Auger shift predictions are however poor in all cases. Absolute total static relaxation and extra-atomic relaxation values have been assessed by using the Auger parameter of Lang and Williams and relativistic atomic calculations for the free atom and its ions. These extra-atomic relaxation components are not additive but rather obey an average contribution behavior. The relaxation shift values have been compared with those obtained from the original Auger parameter (α) of Wagner. The correlation of 1s and 2p binding energies suggested a revised relationship for the Wagner Auger parameter and an equivalent simple form of the Lang and Williams parameter which can be used with satisfactory results when only the usual experimental binding energy (2p) is available in conjunction with the Auger shift.