Iridium Isotopes Research Articles

Laser isotope separation of 192Ir

The following two-step isotope selective photoionization process has been studied for the separation of 192Ir isotope from natural Iridium irradiated in a medium flux reactor for 28 days.5d76s2F9/240.0cm−1→247.5871nm5d76s6p40389.83cm−1J=9/2→307.9nmIr+Density matrix formalism has been used for the investigation of laser isotope separation process. Optimum system parameters such as peak power densities of the excitation and ionization lasers, bandwidth of the excitation laser, angular divergence limit to the atomic ensemble have been derived. Effects of number density and ion travel distance prior to collection on charge exchange probability have also been studied. It has been shown that it is possible produce ∼98% enriched 192Ir at rate of 82 μg/h (27.9 GBq/h or 0.76 Ci/h) which can provide activity of 334 TBq/g or 9027 Ci/g. The enriched 192Ir can be used in both high-dose brachytherapy and high speed radiography. This is the first ever study on the laser based enrichment of Iridium isotopes.

Generation of cross section for neutron induced nuclear reaction on iridium and tantalum isotope using machine learning technique

In this work, we proposed a new approach in generating nuclear data using machine learning techniques. This paper focused on generation of nuclear cross section for neutron induced-nuclear reaction on iridium isotopes (Ir-191) and tantalum isotopes (Ta-181) target, specifically 191Ir (n,p)191Os and 181Ta (n, 2n)180Ta using random forest algorithms. The input consists of experimental datasets obtained from EXOR and simulated datasets from TALYS 1.9. We found that the regression curve generated by our model is in good agreement with the evaluated nuclear data library ENDF/B-VII.0, which is set as the benchmark. This shows a potential in building a machine learning model for generating nuclear cross section data for both well studied and understudied nuclear reaction.

Comparison of model predictions with measured proton-induced production of nickel and iridium isotopes

Comparison of model predictions with measured proton-induced production of nickel and iridium isotopes

Odd deformed nuclei with $\gamma$ γ -instability

The properties of deformed odd nuclei away from the E(5/4) critical point have been studied by using an adjustable Kratzer potential for the even-even core coupled to a fermion moving in a single j = 3/2 shell. This choice preserves the $\gamma$ -instability of the whole system and gives precise analytic predictions for spectra and transitions rates, that are compared with available spectroscopic information in iridium isotopes.

Neutron scattering length determination by means of total scattering

A new method for the measurement of bound coherent neutron scattering lengths is reported. It is shown that a relative measurement of the neutron scattering length, {\overline b}, of an element can be made by analysis of the neutron correlation function of a suitable oxide crystal powder. For this analysis, it is essential to take into account the average density contribution to the correlation function, as well as the contributions arising from distances between atoms in the crystal. The method is demonstrated and verified by analysis of the neutron correlation function for the corundum form of Al2O3, yielding a value {\overline b} = 3.44 (1) fm for Al, in good agreement with the literature. The method is then applied to the isotopes of iridium, for which the values of the scattering lengths were unknown, and which are difficult to investigate by other methods owing to the large cross sections for the absorption of neutrons. The neutron correlation function of a sample of Sr2IrO4 enriched in 193Ir is used to determine values {\overline b} = 9.71 (18) fm and {\overline b} = 12.1 (9) fm for 193Ir and 191Ir, respectively, and these are consistent with the tabulated scattering length and cross sections of natural Ir. These values are of potential application for obtaining improved neutron diffraction results on iridates by the use of samples enriched in 193Ir, so that the severe absorption problems associated with 191Ir are avoided. Rietveld refinement of the neutron diffraction pattern of isotopically enriched Sr2IrO4 is used to yield a similar result for Ir. However, in practice the Rietveld result is shown to be less reliable because of correlation between the parameters of the fit.

Measurement of activation cross sections of alpha particle induced reactions on iridium up to an energy of 50 MeV

Cross sections of alpha particle induced nuclear reactions on iridium were investigated using a 51.2-MeV alpha particle beam. The standard stacked-foil target technique and the activation method were applied. The activity of the reaction products was assessed without chemical separation using high resolution gamma-ray spectrometry. Excitation functions for production of gold, platinum and iridium isotopes (196m2Au, 196m,gAu, 195m,gAu, 194Au, 193 m,gAu, 192Au, 191m,gAu, 191Pt, 195mPt, 194gIr, 194mIr, 192gIr, 190gIr and 189Ir) were determined and compared with available earlier measured experimental data and results of theoretical calculations using TALYS code system. Cross section data were reported for the first time for the natIr(α,x)196m2Au, natIr(α,x)196m,gAu, natIr(α,x)191Pt, natIr(α,x)195mPt, natIr(α,x)194gIr, natIr(α,x)194mIr, natIr(α,x)190gIr and natIr(α,x)189Ir processes. A possible production route for 195mPt, the potentially important radionuclide in nuclear medicine, is discussed.

Cross section of α-induced reactions on iridium isotopes obtained from thick target yield measurement for the astrophysical γ process

The stellar reaction rates of radiative α-capture reactions on heavy isotopes are of crucial importance for the γ process network calculations. These rates are usually derived from statistical model calculations, which need to be validated, but the experimental database is very scarce. This paper presents the results of α-induced reaction cross section measurements on iridium isotopes carried out at first close to the astrophysically relevant energy region. Thick target yields of 191Ir(α,γ)195Au, 191Ir(α,n)194Au, 193Ir(α,n)196mAu, 193Ir(α,n)196Au reactions have been measured with the activation technique between Eα=13.4 MeV and 17 MeV. For the first time the thick target yield was determined with X-ray counting. This led to a previously unprecedented sensitivity. From the measured thick target yields, reaction cross sections are derived and compared with statistical model calculations. The recently suggested energy-dependent modification of the α+nucleus optical potential gives a good description of the experimental data.

Production of platinum radioisotopes at Brookhaven Linac Isotope Producer (BLIP)

The accelerator production of platinum isotopes was investigated at the Brookhaven Linac Isotope Producer (BLIP). In this study high purity natural platinum foils were irradiated at 53.2, 65.7, 105.2, 151.9, 162.9 and 173.3.MeV. The irradiated foils were digested in aqua regia and then converted to their hydrochloride salt with concentrated hydrochloric acid before analyzing by gamma spectrometry periodically for at least 10 days post end of bombardment. A wide range of platinum (Pt), gold (Au) and iridium (Ir) isotopes were identified. Effective cross sections at BLIP for Pt-188, Pt-189, Pt-191 and Pt-195m were compared to literature and theoretical cross sections determined using Empire-3.2. The majority of the effective cross sections (<70 MeV) confirm those reported in the literature. While the absolute values of the theoretical cross sections were up to a factor of 3 lower, Empire 3.2 modeled thresholds and maxima correlated well with experimental values. Preliminary evaluation into a rapid separation of Pt isotopes from high levels of Ir and Au isotopes proved to be a promising approach for large scale production. In conclusion, this study demonstrated that with the use of isotopically enriched target material accelerator production of selected platinum isotopes is feasible over a wide proton energy range.

Low energy cyclotron production and cyclometalation chemistry of iridium-192

This work demonstrates the labelling of a novel class of iridium lumophore with radioiridium, as proof-of-feasibility for producing and using the medically useful isotope iridium-192. Natural osmium was electroplated onto silver target backings in basic media and irradiated for up to two hours with ≤20μA of 12.8MeV protons. A range of iridium isotopes were generated, characterized and quantified using γ-spectroscopy methods. The target material was removed from the backings via oxidative dissolution with hydrogen peroxide, and the iridium radioisotopes isolated using an anion exchange resin. Both no-carrier-added as well as carrier-added formulations were then used in subsequent cyclometalation reactions.

Noble metals in oncology.

Worldwide research groups are searching for anticancer compounds, many of them are organometalic complexes having platinum group metals as their active centers. Most commonly used cytostatics from this group are cisplatin, carboplatin and oxaliplatin. Cisplatin was used fot the first time in 1978, from this time many platinum derivatives were created. In this review we present biological properties and probable future clinical use of platinum, gold, silver, iridium and ruthenium derivatives. Gold derivative Auranofin has been studied extensively. Action of silver nanoparticles on different cell lines was analysed. Iridium isotopes are commonly used in brachyterapy. Ruthenium compound new anti-tumour metastasis inhibitor (NAMI-A) is used in managing lung cancer metastases. Electroporation of another ruthenium based compound KP1339 was also studied. Most of described complexes have antiproliferative and proapoptotic properties. Further studies need to be made. Nevertheless noble metal based chemotherapheutics and compounds seem to be an interesting direction of research.

Isomers, nuclear structure and spectroscopy

Isomers and their roles in discovery and as probes of nuclear structure are discussed, with a focus on neutron-rich nuclei in the mass 180–190 region. Long-lived, high-K isomers are predicted in the heavy hafnium nuclei for example, some of which should be accessible by projectile fragmentation and deep-inelastic reactions. Progress with these reactions in reaching a broad range of isotopes to the right of the stability line is summarized. Recent results for isomers in the iridium and osmium isotopes produced in deep-inelastic reactions and studied with time-correlated γ-ray spectroscopy are presented as examples. These studies venture into the border region where well-deformed prolate shapes give way to soft, transitional nuclei. Prolate, oblate and triaxial structures are predicted, but with shapes that depend sensitively on the multi-particle configurations. Dynamical effects such as rotation alignment also play a significant role and produce isomeric states. In some cases, very low-lying multi-quasiparticle intrinsic states are predicted but these are possibly missed with current approaches. The prospects for the identification and characterization of such exotic isomers using new storage ring techniques, that might also provide a window into exotic states populated in their subsequent decay are outlined, as is the potential for studies with beams of isomers themselves.

Discovery of tantalum, rhenium, osmium, and iridium isotopes

Currently, thirty-eight tantalum, thirty-eight rhenium, thirty-nine osmium, and thirty-eight iridium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Long-lived three-quasiparticle isomers in 191Ir and 193Ir with triaxial deformation

Deep-inelastic reactions have been used to populate high-spin states in the iridium isotopes. New results include the identification of particularly long-lived three-quasiparticle isomers in 191Ir and 193Ir, with mean-lives of 8.2(7) s and 180(3) μs respectively, decaying into newly identified states of the h11/2 proton bands and into other structures. Spins and parities of Jπ=31/2+ are suggested for both, consistent with coupling of the 11/2−[505] proton to the 10− two-neutron excitations in the cores. These and other configurations are discussed in the context of configuration constrained potential-energy-surface calculations. All calculated intrinsic states are expected to be associated with triaxial shapes and the extreme isomerism observed is attributed to spin-trapping rather than K-hindrance.

The Discoverers of the Rhodium Isotopes

This is the fifth in a series of reviews on the circumstances surrounding the discoveries of the isotopes of the six platinum group elements. The first review on platinum isotopes was published in this Journal in October 2000 (), the second on iridium isotopes in October 2003 (), the third on osmium isotopes in October 2004 () and the fourth on palladium isotopes in April 2006 ().

Dependence of the cross sections for Ir isotopes on the values of Qgg in the heavy ion collision

197Au were irradiated with 47 MeV/u 12C ions. Iridium was produced via the multinucleon transfer reactions in bombardments of 197Au with 12C. and was separated radiochemically from Au and the mixture of the reaction products. The γ radioactivities of Ir isotopes were measured by using a HPGe detector. The production cross sections of Ir isotopes were determined from activities of Ir isotopes at the end of bombardment and the other relative data. It has been found that the cross sections for neutron-rich isotopes of iridium show an exponential dependence on the values of Qgg. Our experimental results also demonstrate lack of correlation between the cross sections and Qgg in the case of neutron-deficient isotopes of iridium. The fact can be explained from that neutron-rich isotopes of iridium were produced in the deep inelastic transfer reactions.

Analysis of Electron Paramagnetic Resonance Spectra with Very Large Quadrupole Couplings

Frozen solution electron paramagnetic resonance (EPR) spectra are reported for [(η 4 -cod)Rh(μ-RNNNR) 2 -Ir(CO) 2 ] + (cod = 1,5-cyclooctadiene), [(PPh 3 )(CO)Rh(μ-RNNNR) 2 Ir(CO)(PPh 3 )] + (R = p-tolyl) and [Tp'Ir-(CO)(PPh 3 ] + (Tp' = hydrotris(3,5-dimethylpyrazolyl)borate). In the first spectrum, the Rh hyperfine coupling dominates and there are no significant quadrupolar effects. In the second spectrum, the low-field (g x and g y ) features are 1:2:1 triplets rather than 1:1:1:1 quartets (I = 3/2 for 1 9 1 Ir and 1 9 3 Ir), and in the third, the x and y features appear to be doublets. These anomalies result from the very large quadrupole moment for the iridium isotopes. This can be partially understood from a perturbation theory treatment, but quantitative simulations require direct matrix diagonalization and careful treatment of the problem, with respect to the orientation of the electron spin and nuclear spin quantization axes. The theoretical aspects of the calculations are presented, together with an interpretation of the results in terms of the electronic structures of the complexes.

The Discoverers of the Osmium Isotopes

This is the third in a series of reviews of circumstances surrounding the discoveries of the isotopes of the six platinum group elements; it concerns the discovery of the thirty-four isotopes of osmium. The first review on platinum isotopes was published in this Journal in October 2000, and the second review on iridium isotopes was published in October 2003 .

The Discoverers of the Iridium Isotopes

This paper is the second in a series of reviews of work performed that led up to the discoveries of the isotopes of the six platinum group elements. The first review, on platinum isotopes, was published in this Journal in October 2000 . Here, a brief history of the discovery of the thirty-six known isotopes of iridium in the sixty-seven years from the first discovery in 1934 to 2001 is considered in terms of the discoverers.

Analysis of Electron Paramagnetic Resonance Spectra with Very Large Quadrupole Couplings

Frozen solution electron paramagnetic resonance (EPR) spectra are reported for [(η 4 -cod)Rh(μ-RNNNR) 2 -Ir(CO) 2 ] + (cod = 1,5-cyclooctadiene), [(PPh 3 )(CO)Rh(μ-RNNNR) 2 Ir(CO)(PPh 3 )] + (R = p-tolyl) and [Tp'Ir-(CO)(PPh 3 ] + (Tp' = hydrotris(3,5-dimethylpyrazolyl)borate). In the first spectrum, the Rh hyperfine coupling dominates and there are no significant quadrupolar effects. In the second spectrum, the low-field (g x and g y ) features are 1:2:1 triplets rather than 1:1:1:1 quartets (I = 3/2 for 1 9 1 Ir and 1 9 3 Ir), and in the third, the x and y features appear to be doublets. These anomalies result from the very large quadrupole moment for the iridium isotopes. This can be partially understood from a perturbation theory treatment, but quantitative simulations require direct matrix diagonalization and careful treatment of the problem, with respect to the orientation of the electron spin and nuclear spin quantization axes. The theoretical aspects of the calculations are presented, together with an interpretation of the results in terms of the electronic structures of the complexes.

Measurement of isotopic cross sections of spallation residues in 800 [formula omitted] MeV 197Au[formula omitted]p collisions

The spallation of 197Au by 800 MeV protons was investigated in inverse kinematics at GSI, Darmstadt, by use of a 197Au beam bombarding a liquid-hydrogen target. The fragment separator (FRS) was used to select and identify the reaction products prior to β decay. The individual production cross sections and the kinematic properties of 380 isotopes for all elements between mercury (Z=80) and neodymium (Z=60) have been measured. A comparison with a Monte-Carlo calculation based on the two-step model of the spallation reaction is given. The isotopic cross-section distribution of iridium isotopes is compared to that resulting from the aluminium-induced fragmentation of 197Au. The mean kinetic energies of the fragments are deduced from the experimental data. The importance of the new data to improve our understanding of the spallation mechanism is discussed.