[en] An analytical method is described for the mass spectrometric determination of molybdenum abundance values. The results of analyses of three molybdenum mineral samples are presented and compared with the results of other authors. It is shown that the fine variations of molybdenum in natural minerals cannot be analysed with currently available mass spectrometers

[en] Penning-trap measurements on stable ^92,94-98,100Mo isotopes have been performed with relative accuracy of 1.10^-8 with the JYFLTRAP Penning-trap mass spectrometer by using ⁸⁵Rb as a reference. The Mo isotopes have been found to be about 3keV more bound than given in the Atomic Mass Evaluation 2003 (AME03). The results confirm that the discrepancy between the ISOLTRAP and JYFLTRAP data for ^101-105Cd isotopes was due to an erroneous value in the AME03 for ⁹⁶Mo used as a reference at JYFLTRAP. The measured frequency ratios of Mo isotopes have been used to update mass-excess values of 30 neutron-deficient nuclides measured at JYFLTRAP. (orig.)

No abstract available

[en] The results of precise measurements of the energies of the 2psub(3/2)-1ssub(1/2) and 2psub(1/2)-1ssub(1/2) muonic X-ray transitions of ⁹²Mo, ⁹⁴Mo, ⁹⁵Mo, ⁹⁶Mo, ⁹⁷Mo, ⁹⁸Mo and ¹⁰⁰Mo are reported. The data were analyzed in terms of the Barett moments (rsub(k)e^-sup(ar)) of the nuclear charge distributions from which the equivalent nuclear radii Rsub(k) and the differences ΔRsub(k) between neighboring isotopes were computed. Systematic shell effects have been observed at the neutron numbers N = 50 and N = 56. (orig.)

[en] The isotopic composition of molybdenum has been measured with high precision using a thermal ionization mass spectrometer, the linearity of which has been verified by measuring the isotopically-certified reference material for strontium (NIST 987). The abundance sensitivity of the mass spectrometer in the vicinity of the molybdenum ion beams has been carefully examined to ensure the absence of tailing effects. Particular care was given to ensuring that potential isobaric interferences from zirconium and ruthenium did not affect the measurement of the isotopic composition of molybdenum. Gravimetric mixtures of two isotopically enriched isotopes, ⁹²Mo and ⁹⁸Mo, were analyzed mass spectrometrically to calibrate the mass spectrometer, in order to establish the isotope fractionation of the spectrometer for the molybdenum isotopes. This enabled the ''absolute'' isotopic composition of molybdenum to be determined. An accurate determination of the isotopic composition is required in order to calculate the atomic weight of molybdenum, which is one of the least accurately known values of all the elements. The absolute isotope abundances (in atom %) of molybdenum measured in this experiment are as follows: ⁹²Mo=14.5246±0.0015; ⁹⁴Mo=9.1514±0.0074; ⁹⁵Mo=15.8375±0.0098; ⁹⁶Mo=16.672±0.019; ⁹⁷Mo=9.5991±0.0073; ⁹⁸Mo=24.391±0.018; and ¹⁰⁰Mo=9.824±0.050, with uncertainties at the 1s level. These values enable an atomic weight A_r(Mo) of 95.9602±0.0023 (1s) to be calculated, which is slightly higher than the current Standard Atomic Weight A_r(Mo) =95.94±0.02 and with a much improved uncertainty interval. These 'absolute' isotope abundances also enable the Solar System abundances of molybdenum to be calculated for astrophysical purposes. Of particular interest are the Solar System abundances of the two p-process nuclides--⁹²Mo and ⁹⁴Mo, which are present in far greater abundance than p-process theory suggests. The Solar System abundances for ⁹²Mo and ⁹⁴Mo of 0.364±0.012 and 0.230±0.008 respectively, (with respect to silicon =10⁶ atoms), are the most accurate values measured to date, and should therefore be adopted in future p-process calculations, rather than the existing values of 0.378±0.021 and 0.236±0.013, respectively

[en] The cross section calculation of ^102,104,106Mo below 20 MeV was carried out. Because there are no any experimental data, for three unstable isotopes of element molybdenum, our results of ^102,104,106Mo are compared each other and with evaluated data of ^{92,94,96,98,100}Mo which are generally in good accordance with experimental data. In our final evaluation files, the most of the data are directly taken from our calculated values, which are reasonable in physics. (authors)

[en] The isotopic compositions of molybdenum in six uranium-rich samples from the Oklo Zone 9 natural reactor were accurately measured by thermal ionization mass spectrometry. The samples were subjected to an ion exchange separation process that removed the isobaric elements zirconium and ruthenium, with high efficiency and a low blank. Molybdenum possesses seven isotopes of which ^92,94,96Mo are unaffected by the fission process, enabling the raw data to be corrected for isotope fractionation by normalising to ⁹²Mo/⁹⁶Mo, and to use ⁹⁴Mo to correct for the primordial component in each of the fission-produced isotopes. This enables the relative fission yields of Mo to be calculated from the isotopic composition measurements, to give cumulative fission yields of 1:0.941:0.936:1.025 for ^95,97,98,100Mo, respectively. These data demonstrate that the most important nuclear process involved in reactor Zone 9 was the thermal neutron fission of ²³⁵U. The consistency of the relative cumulative fission yields of all six samples from different locations in the reactor, implies that Mo is a mobile element in the uraninite comprising Zone 9, and that a significant fraction of molybdenum was mobilized within the reactor zone and probably escaped from Zone 9, a conclusion in agreement with earlier published work. (author)

[en] A good description of the quadrupole moments is obtained by investigating ^{94,96,98,100,102,104,106,108}Mo isotopes in terms of the interacting boson model. After the positiveparity states and electromagnetic-transition rates B(E2) of even-mass Mo nuclei were calculated it was seen that there is a good agreement between the obtained results and some previous experimental data. At the end of the quadrupole moment calculations it was proved that the results agree well with the previous experimental data.

[en] Electrochemical, colorimetric, gravimetric, spectroscopic, and radiochemical methods for the determination of molybdenum are summarized in this book. Some laboratory procedures are described in detail while literature citations are given for others. The reader is also referred to older comprehensive reviews of the analytical chemistry of molybdenum. Contents, abridged: Gravimetric methods. Titrimetric methods. Colorimetric methods. X-ray fluorescence. Voltammetry. Catalytic methods. Molybdenum in non-ferrous alloys. Molydbenum compounds

No abstract available