Isotopic Measurements of Uranium Using Inductively Coupled Plasma Cavity Ringdown Spectroscopy

Abstract

Inductively coupled plasma cavity ringdown spectroscopy (ICP-CRDS) is applied to isotopic measurements of uranium. We have successfully obtained the isotopic-resolved spectra of uranium at three different atomic/ionic transition lines, 286.57, 358.49, and 409.01 nm. Of the three lines, the largest isotope shift of approximately 9 pm was measured at the 286.57 ionic line. Isotopic-resolved spectra were recorded in ratio of 1:1 (235U/238U, 2.5 micrograms/mL) and at the natural abundance ratio of 0.714% (235U/238U, 1.25 micrograms/mL 235U). The smallest measurable isotope shift of approximately 3 pm was determined for the 409.01 nm ion spectral line. Detection limits (DL) were obtained under optimized ICP operating conditions to be in the range of 70-150 ng/mL, except for the 238U component of the 286.57 nm line (300 ng/mL). This latter result was determined to be due to a strong, previously unreported, absorption interference from the argon plasma. The 235U isotope component (DL 70 ng/mL) was found to be unaffected. This work demonstrates the applicability of ICP-CRDS for uranium isotopic measurements. The potential of development of a field-deployable, on-line uranium isotope monitor using plasma-CRDS is discussed.

An Optical Offgas Sensor Network Incorporating a HG Cavity Ringdown Spectrometer and IR Diode Lasers

“…The objective of this research project was the writing, implementation and testing of the Labview software to be used in Cavity Ring-down experiments for duel channel monitoring. Our overall conclusion, from both this work and our previous studies, [4][5][6][7][8][9][10][11] is that mercury CRDS remains the most promising technique to provide real-time monitoring of elemental mercury in exhaust gas streams. However, the UV linewidth of tunable light source must be sufficiently narrow to allow the differentiation of the mercury from the SO 2 background and the repetition rate must be sufficiently high (~50 Hz) to provide real-time measurements.…”

Cavity Ringdown Laser Absorption Spectroscopy

“…235 U existing in 238 U with the natural abundance ratio of 0.79% was also measured. (21) This research demonstrated high-resolution isotopic analysis with high detection sensitivity using the P-CRDS technique.…”

“…(197) The ICP-CRDS system was applied to isotopic measurements of uranium at three different wavelengths: 286, 358, and 409 nm. (21) The U transitions at 286 and 409 nm are ionic transitions, but the U transition at 358 nm is an atomic transition. With the optimized ICP-CRDS system, the detection limits of U and its isotopes were in the nanogram per microliter levels.…”

“…With the optimized ICP-CRDS system, the detection limits of U and its isotopes were in the nanogram per microliter levels. (21) Figure 7 shows typical isotopic measurements of uranium with a 50%/50% mixture of 235 U and 238 U. 235 U existing in 238 U with the natural abundance ratio of 0.79% was also measured.…”

“…A review of P-CRDS for elemental and isotopic measurements has recently been published. (21,77) This section incorporates an update on the development of the P-CRDS technique since the last review. Emphasis is placed on the improvement of the P-CRDS technique and isotopic measurements.…”