p3/2-alignment following heavy ion impact

The energy dependence of the alignment of₄₂Mo,₄₇AgL ₃ shell and₇₉Au,₉₀ThM ₃ shell following impact ionization by ions with atomic numberZ ₁=2 (helium) toZ ₁=18 (argon) was studied with a 5 in Johansson crystal spectrometer analyzing the degree of X-ray polarization. Experimental information about the amount of multiple ionization was obtained. The observed small negative alignment is concerned to be due to dealignment by couplings between the created vacancies. Large positive values of the alignment parameter as previously reported for the₇₉AuL ₃ shell is slow heavy ion collisions were not observed.     

New procedure calculation of K-shell ionization cross sections by proton impact

The database, which relies on different compilations available in the literature and on other experimental values extracted from papers published from 1992 till 2010, is used, within the individual treatment of the elements from beryllium (⁴Be) to uranium (⁹²U), to deduce the empirical cross sections. These experimental data can be presented in a single curve, depending on a scaling law extracted from studies in the most familiar theories of collision (PWBA and BEA). Then, a fourth order polynomial was used to fit very well the existing database of K-shell ionization cross sections by proton. This procedure generates a new set of parameters to calculate empirical cross sections. Following the present procedure, our results are compared with those obtained using the ECPSSR model where a discrepancy is observed in the low-proton energy regime.     

Multiple ionization effects on total L-shell X-ray production cross sections by proton impact

The effect of multiple ionization on total L-shell X-ray production cross sections by proton impact, with energies below 1 MeV, on elements with atomic numbers in the range 26–55 was studied. Measurements of those cross sections for several elements were also done to enlarge the experimental database. Several tables for atomic parameters (fluorescence yields and Coster–Kronig transition probabilities) were used. The agreement between theory and experiment was optimized when average fluorescence yields given by Hubbel et al. (J. Phys. Chem. Ref. Data 23(2) (1994) 339) and a multiple ionization model proposed by Lapicki et al. (Phys. Rev. A 34(5) (1986) 5813) were used together. Thus, improvements to theoretical predictions for ionization cross sections should consider first a correct set of atomic parameters.     

L-shell ionization in Au by O5+-and Ni5+-ion impact

TheL X-ray production cross sections in gold by 60 to 72 MeV O⁵⁺ ions and 58 to 87 MeV Ni⁵⁺-ions have been measured. TheL-subshell ionization cross sections derived from these experimental results have been compared with the direct ionization theories viz. plane wave Born approximation (PWBA) theory and modified perturbed-stationary-state theory with energy loss, Coulomb deflection and relativistic effects (MECPSSR). A new procedure has been described to account for the change in the yield ratioLβ₁/Lβ_{2, 15} with energy, for Ni⁵⁺-ion impact on gold. TheL sub-shell ionization cross sections have been derived fromLβ₁,Lβ₄ andLβ_{2, 15} lines of theLβ group in addition to those calculated by the conventional Datz TRY3 technique usingLα,Lγ₁ andLγ_{2, 3} X-ray lines. From the shift in the energies of variousL X-ray lines and changes in their intensities, 3 and 5 spectator vacancies in theM- andN-shells in gold have been estimated with O⁵⁺-ion impact while 7, 20 and 4 to 6 spectator vacancies have been inferred in theM-,N-andO-shells respectively with Ni⁵⁺-ion impact in the energy range of the projectiles undertaken in the present studies.     

Nd,Yb, Au and UL-subshell ionization probabilities for 92 MeV Ar impact

The Nd, Yb, Au and UL-subshell X-ray emission probabilities as function of the impact parameter have been measured by X-ray—particle coincidence for 92 MeV Ar impact. The derivedL-subshell ionization probabilities show severe deviations from first order perturbation theory (SCA + corrections), although the totalL-shell ionization probabilities are still fairly well described by this approach. As is obvious from the data analysis, the discrepancy is due toL-substate coupling during the collision, which has a strong influence on the subshell ionization process, but is neglected in this theoretical approach. The observed influence of the multiple outer shell ionization on the measured data is also discussed.     

The influence of the electron wave function on the PtL I andL III ionization probabilities by 3.6 MeV he impact

For 3.6 MeV He impact theL _I andL _III subshell ionization probabilities of Pt have been measured. Due to relativistic effects in the electron wave functions, theL _I subshell ionization probabilityI _LI (b) is strongly enhanced at small impact parameters exceeding evenI _LIII (b) in nice agreement with the SCA theory.     

S K-shell ionization cross sections by protons of 0.8 to 3.0 MeV

Thick targets containing 2, 4, 8 and 50% by weight of S in a Li₂B₄O₇ matrix and pure S have been irradiated by protons in the energy range 0.8 to 3.0 MeV. The S K-shell ionization cross sections have been measured and compared to available theoretical and experimental data.     

Opto-structural characterization of proton (3 MeV) irradiated polycarbonate and polystyrene

Polycarbonate (Makrofol-N) and polystyrene thin films were irradiated with protons (3 MeV) under vacuum at room temperature with the fluence ranging from 1×10¹⁴ to 1×10¹⁵ protons cm⁻². The change in optical properties, degradation of the functional groups and crystallinity of the proton-irradiated polymers were investigated with UV–vis, Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) techniques, respectively. The UV–vis analysis revealed that the optical band gap of irradiated Makrofol-N is reduced by 30% as compared to 27.5% in polystyrene at highest fluence of 1×10¹⁵ protons cm⁻², owing to higher electronic energy loss of protons in Makrofol-N. The calculations of the number of carbon atoms per conjugation length, N and number of carbon atoms per clusters, M embedded in the network of polymers further revealed that Makrofol-N is more modified as compared to polystyrene on proton irradiation. FTIR results reveal the reduction in absorption intensity of the main characteristic bands of both the polymers after irradiation. The proton-irradiated Makrofol-N shows a strong decrease of almost all of its characteristic absorption bands at about 1×10¹⁴ protons cm⁻². Beyond a critical dose an increase of almost all its characteristic bands are noticed, however, no such effect had been observed in polystyrene at this particular fluence. Appearance of new –OH groups was observed at the higher fluences in the FTIR spectra of both proton-irradiated polymers. XRD measurements show the decrease of the main peak intensity and the crystallite size, confirming the increase of amorphization in polymers under irradiation.     

K-shell ionization induced by 30 MeV/u argon and neon beams

We have studiedK-shell ionization induced by 30 MeV/u Ne and Ar projectiles on target atoms with atomic numbers ranging from 27 to 90. X-ray production cross sections and energy shifts were measured with Si(Li) detectors. In most cases satisfactory agreement between measurements and theoretical direct ionization cross sections is obtained when the contribution of electron capture is included. The influence of multiple ionization on the fluorescence yield ω _K is discussed.     

G3 calculations of the proton affinity and ionization energy of dimethyl methylphosphonate

Dimethyl methylphosphonate (DMMP), an important flame retardant in lithium-ion batteries, has been studied theoretically. The energy, enthalpy, and Gibbs free energy of DMMP and its protonated form (DMMP-H⁺) have been calculated using the high-level ab initio methods G3(MP2), G3(MP2)//B3LYP, G3, G3//B3-LYP, and CBS-QB3. All calculated proton affinities showed good agreement with experiment (within 1.5%), with the best values being obtained with G3MP2. At this level of theory, the calculated proton affinity of DMMP is 895 kJ · mol^?1. The ionization potential (9.94 eV) was calculated using the related procedure G3(MP2)-RAD, and also showed excellent with experiment (0.6%). Hydrogen bonding in DMMP-H⁺ has also been studied.     

14 MeV neutron activation analysis of gold jewellery

Samples of nominal 18 carat and 21 carat gold jewelleries from the local market were non-destructively bulk analyzed using neutron activation analysis. Neutrons of 14 MeV energy were used with a fast pneumatic sample transfer system. The actual gold contents, as well as the composition of the base metals in these samples were determined. The fast neutron activation was found to be an efficient, quick and accurate method of characterizing the precious metal objects routinely in bulk, with a large sample throughput. The results demonstrate the commercial availability of the technique for non-destructive bulk analysis of precious metal objects.     

Fast determination of gold in large mass samples of gold ores by photoexcitation reactions using 10 MeV bremsstrahlung

The determination of gold is based on the photoexcitation reaction ¹⁹⁷Au(γ,γ’)^197mAu with the half-life of 7.73 seconds and energy of emitted gamma-rays of 279 keV. Three 100 ml aliquots of coarsely ground Au-ore (grains <2 mm) corresponding to ca. 150–180 g were irradiated for 20 seconds with bremsstrahlung of maximum energy 10 MeV produced by a microtron at the electron beam current of 30–40 μA, 1–10 times reactivation was applied. After 3 seconds of decay, samples were measured for 20 seconds using scintillation or semiconductor gamma-spectrometry with the detection limits for an ideal sample down to 0.5 μg·g⁻¹ and 0.1–0.2 μg·g⁻¹ of Au, respectively. Content of U and Th undergoing photo-fission increases the detection limits several times.     

Differentiation of isomeric 1-, 3- and 7-deazaadenosines by electron ionization mass spectrometry

The low and high resolution electron ionization mass spectra of 1-deazaadenosine, 3-deazaadenosine and 7-deazaadenosine are reported. Fragmentation pathways and ion structures are proposed with the aid of linked-scan, daughter-ion spectra. Results indicate that the N-3 position of the purine ring serves as an important acceptor site in fragmentation processes involving hydrogen transfer from the sugar to the base. A mixture analysis of the trimethylsilyl derivatives of adenosine, 1-, 3- and 7-deazaadenosine by combined gas chromatography/mass spectrometry is also described.     

Radiation damage induced in Zircaloy-4 by 2.6 MeV proton irradiation

Journal of Radioanalytical and Nuclear Chemistry - Radiation damage induced in Zircaloy-4 by 2.6&nbsp;MeV proton irradiation at low doses was studied. Our aim is to emulate the effect of...     

The fragmentation of 5- and 3-substituted thiophene-2-carboxamides under electron impact

The 70 eV electron impact mass spectra of twelve 5- and 3-substituted thiophene-2-carboxamides are discussed with the aid of exact mass measurements and labelling experiments. All mass spectra exhibit pronounced molecular ions. Some isomeric 5- and 3-substituted title compounds can be differentiated by mass spectrometry. The fragmentation is influenced by a strong ‘ortho-effect’ which activates the NH₃ elimination. In the other cases the most important fragmentation is NH₂˙ loss, followed by CO elimination.     

The behaviour of 3-methyl-5-(o-r-styryl)-4-nitroisoxazoles under electron impact. I

The mass spectra of several 3-methyl-5-(o-R-styryl)-4-nitroisoxazoles have been studied. The fragmentation patterns and mechanisms postulated have been confirmed by the determination of the metastable peaks.