0000000000185444
AUTHOR
A. Waldek
Resonance ionization mass spectrometry for ultratrace analysis of plutonium with a new solid state laser system
Abstract Resonance ionization mass spectrometry (RIMS) is well-suited for isotope selective ultratrace analysis of long-lived radioactive isotopes due to its high element and isotope selectivity and good sensitivity. For the analysis of plutonium with a pulsed RIMS apparatus, a powerful, reliable and easy to handle Nd:YAG pumped titanium–sapphire laser system has been developed and combined with a time-of-flight mass spectrometer. Spectroscopic measurements led to an efficient three step excitation and ionization scheme for plutonium with λ1 = 420.76 nm, λ2 = 847.28 nm, and λ3 = 767.53 nm. The isotope shifts in this scheme for the plutonium isotopes 238 Pu through 244 Pu have been determine…
First Determination of the Ionization Potential of Actinium and First Observation of Optical Transitions in Ferminm
For the determination of the first ionization potential of actinium, 227Ac was electrodeposited on a Ta backing and covered with ~1 μm Zr. From this filament, Ac atoms were evaporated at ≥ 1250 °C. By resonant excitation with UV light of 388.67 nm and subsequent excitation with light of ca. 568 nm, Ac was ionized in an external electrical field. By determining the ionization thresholds as a function of the electrical field strength and by extrapolation to zero field strength, the first ionization potential of 43398(3) cm−1 = 5.3807(3) eV was measured.About 1 ng of 255Fm, half life 20.1 h, was prepared at ORNL by milking from 255Es produced in the High Flux Isotope Reactor and shipped to Mai…
Trace analysis of plutonium in environmental samples by resonance ionization mass spectroscopy (RIMS)
Resonance ionization mass spectroscopy (RIMS) is well suited for trace analysis of long-lived radioisotopes in environmental, biological and technical samples. By multiple resonant laser excitation and ionization of the elemental atoms under investigation, an extremely high element selectivity can be achieved. In addition, isotope selectivity is obtained by subsequent mass analysis. The excellent sensitivity results from the large atomic cross-sections in the excitation–ionization process and the good detection efficiency for ions. The element selectivity of RIMS allows a simplified procedure for the chemical preparation of the samples compared to the requirements of thin sources for α-spec…
Resonance ionization mass spectroscopy for trace determination of plutonium in environmental samples
Resonance ionization mass spectroscopy (RIMS) is a sensitive and isotope selective method and well suited for trace analysis of plutonium in the environment. After the chemical isolation of plutonium from soil, air filters or urine, e.g., it is electrolytically deposited as hydroxide on a tantalum backing and covered with a thin titanium layer. By heating such a sandwich filament in the RIMS-apparatus under vacuum an atomic beam of plutonium is produced. The atoms are ionized by a three-step resonant excitation using pulsed dye lasers, and the ions are mass-selectively detected with a time-of-flight (TOF) spectrometer and a multi channel plate detector. RIMS yields a low detection limit of …
Determination of the first ionization potential of einsteinium by resonance ionization mass spectroscopy (RIMS)
Abstract The first ionization potential of einsteinium (IP Es ) was determined by resonance ionization mass spectroscopy (RIMS) using samples with ≤10 12 atoms of 254 Es ( T 1/2 =276 days). This method is based on the measurement of photoionization thresholds as a function of applied electric field strength, followed by extrapolation to zero field strength to yield IP Es . An atomic beam of Es was created by heating a filament on which einsteinium was electrodeposited from an aqueous solution onto a tantalum backing and covered with titanium metal. Es atoms were ionized via a three-step excitation scheme, and the ions mass-selectively detected in a time-of-flight (TOF) mass spectrometer. Th…
Recent developments in and applications of resonance ionization mass spectrometry
Resonance Ionization Mass Spectrometry (RIMS) has nowadays reached the status of a routine method for sensitive and selective ultratrace determination of long-lived radioactive isotopes in environmental, biomedical and technical samples. It provides high isobaric suppression, high to ultra-high isotopic selectivity and good overall efficiency. Experimental detection limits are as low as 106 atoms per sample and permit the fast and sensitive determination of ultratrace amounts of radiotoxic contaminations. Experimental arrangements for the detection of different radiotoxic isotopes, e.g. 236–244Pu, 89,90Sr and 99Tc in environmental samples are described, and the application of RIMS to the ul…
Determination of the first ionization potential of nine actinide elements by resonance ionization mass spectroscopy (RIMS)
The high sensitivity of RIMS enables the precise determination of the first ionization potential of actinide elements with a sample size of ≤1012 atoms. By multiple resonant laser excitation, the actinide atoms under investigation are ionized in the presence of an electric field, and the ions are mass-selectively detected in a time-of-flight spectrometer. The first ionization potential is obtained by scanning the wavelength of the laser used for the last excitation step across the ionization threshold Wth—indicated by a sudden increase of the ion count rate—at various electric field strengths. Extrapolation of Wth to electric field strength zero leads directly to the first ionization potent…