Precise measurement of 234U/238U, 235U/238U and 236U/238U isotope ratios in Fukushima soils using thermal ionization mass spectrometry

Коллективные процессы в термической ионизации на поверхности интерметаллида NaAu-=SUB=-x-=/SUB=-

“…Исследования термической ионизации (ТИ) атомов и молекул на поверхности нагретых металлов и их окислов позволили создать непротиворечивую теорию процесса десорбции адсорбированных частиц в виде ионов [1,2]. Практическим применением явления ТИ стали источники ионизации для масс-спектрометрии органических молекул [2][3][4][5][6][7][8][9][10][11][12], для изотопного анализа [13][14][15][16][17][18] и высокочувствительных селективных воздушных детекторов органических соединений [19][20][21][22][23][24][25][26]. Изученность процесса ТИ на эмиттерах из тугоплавких металлов и их окислов позволила использовать ТИ как в качестве метода исследования поверхности твердого тела и процессов в адсорбированном слое, так и для определения характеристик адсорбированных соединений [2][3][4].…”

Rapid and Precise Uranium Isotopic Screening in Natural Water Using Bis(2-ethylhexyl)phosphoric Acid-Modified Membranes

“…The combined knowledge of total uranium concentration and 234 U/ 238 U isotope ratio provides an insight for the various conditions responsible for uranium mobilization in the subsurface. , However, a prime constraint for TIMS measurement is that the analyte should be in its purest chemical form to achieve efficient ionization during analysis. Therefore, elaborate and tedious sample pretreatment and chemical purification steps, employing conventional techniques like solvent extraction, anion-exchange column, or extraction chromatography, are mandatory prior to uranium isotopic analysis by TIMS. − Though recently developed automated ion-exchange/extraction chromatographic techniques coupled with flow injection/sequential injection have considerably minimized the analysis time and effort involved in the traditional purification methods, − these are multistep techniques with comparatively low preconcentration factor, and there could be loss of analytes during one or more steps. A new emerging viable alternative is the direct analysis of uranium preconcentrated in a solid phase that can be loaded on a rhenium filament for TIMS analysis.…”

“…17−21 Apart from uranium concentration, mass spectrometric techniques also provide the isotopic composition of uranium, which is very crucial to understand the source, groundwater dynamics, and hydrochemical behavior of U. The variations of 234 U/ 238 U isotope ratio in groundwater are quite significant due to processes like alpha recoil, oxidation reaction, chemical fractionation, and so forth. The combined knowledge of total uranium concentration and 234 U/ 238 U isotope ratio provides an insight for the various conditions responsible for uranium mobilization in the subsurface.…”

“…The variations of 234 U/ 238 U isotope ratio in groundwater are quite significant due to processes like alpha recoil, oxidation reaction, chemical fractionation, and so forth. The combined knowledge of total uranium concentration and 234 U/ 238 U isotope ratio provides an insight for the various conditions responsible for uranium mobilization in the subsurface. 4,22 However, a prime constraint for TIMS measurement is that the analyte should be in its purest chemical form to achieve efficient ionization during analysis.…”

“…This indicates that the membrane developed in the present work not only separates and preconcentrates uranium from natural water samples but also acts as an efficient promoter for the enhancement of UO + ion intensity, much like the surface modifiers which have to be added externally in an optimum amount during conventional TIMS analysis. The present work marks the beginning of a new era for the rapid measurement of uranium isotopic abundance by monitoring the molecular ions (UO + ), for analyzing the activity ratio of 234 U/ 238 U in natural aquatic samples such as seawater, groundwater, borewell, tap water, and so forth.…”