Measurement of Rb isotope ratio by atomic absorption spectroscopy with multi-microchannel array structure cavity

Abstract

Rubidium isotope analysis has important application value in geological exploration and environmental detection. Based on tunable laser atom absorption spectroscopy technology combined with thermal decomposition of the sample, a rubidium isotope absorption spectroscopy measurement device is bulit to realize rubidium isotope ratio stability detection. And the atomic generator is designed by a new micro-channel array structure, which enhances atomic beam collimation capability, effectively suppresses the doppler effect of the spectrum and improves the resolution of rubidium isotope absorption spectrum. The device adopts tantalum metal to make the atomic generator with a diameter of 6 mm, and the micro-channel array with a diameter of 1 mm is stacked inside the atomic generator which can be heated resistively to 3000 ℃. In this experiment, the rubidium carbonate sample is catalyzed to release rubidium atom beam at high temperature (600 ℃), while a probe laser is used to obtain high resolution rubidium absorption spectrum. The rubidium isotope ratio (<sup>85</sup>Rb: <sup>87</sup>Rb) of natural abundance rubidium carbonate samples is 2.441±0.02 by combining the inversion of the spectral line parameters, the detection error is 4.8%, and the detection limit of <sup>87</sup>Rb is 1.76‰ (3σ). The experimental results show that the multi-microchannel structure reduces the linewidth of rubidum atoms by 450 MHz (half height full width) compared to the single-channel structure, which can effectively distinguish the absorption characteristics of rubidium isotopes. The device has a high detection accuracy and a high spectral resolution, allowing for a possibility for the measurement of metal isotope abundance analysis, which has a broad application prospect.

Highly sensitive spectral measurement of rubidium isotopes using open multi-pass cell in tunable diode laser absorption spectroscopy

“…8,19 In our previous research, we studied the isotope absorption spectrum of rubidium at 780 nm using the micro-channel array structure and theoretically investigated the causes of the Doppler effect. 20 Owing to the smaller isotope shis of rubidium at 794.98 nm, we further conrmed the effectiveness of the micro-channel array structure in reducing the Doppler broadening effect in this study. The experimental results presented in Fig.…”

“…Compared with the standard abundance ratio of 2.593, the relative deviation was 1.16%, which is better than in a previously reported study. 20 The error mainly came from two aspects: (1) the system error introduced by electronic components and (2) the fitting errors in the spectrum fitting process. According to the 3 σ criterion, the limit of detection (LOD) can be given by the following formula: 21 LOD = 3 σ BG / s …”

Atomic absorption spectroscopy detection system based on wavelength modulation and wavelet denoising

“…[4] While mass spectrometry currently serves as a prevalent technology for metal isotope abundance detection, its complex sample pretreatment methods limit its use only in laboratory environments. [5] In recent years, tunable diode laser absorption spectroscopy (TDLAS) technology has attracted widespread attention due to its advantages such as high resolution, strong selectivity, and high sensitivity. [6][7][8] Miyabe et al integrated laser ablation with TDLAS to develop multiple actinide metal isotope abundance detection systems, achieving precision in measuring metal isotope abundance.…”