研究目的
Investigating efficient two-color two-step laser ionization schemes for heavy refractory elements, specifically tantalum and tungsten, to measure ionization cross-sections and hyperfine spectra.
研究成果
The study successfully identified efficient ionization schemes for tantalum and tungsten using a two-color two-step laser resonance ionization technique. The measured excitation and ionization cross sections were sufficiently large for saturation, making the schemes applicable for extracting isotopes of these elements. The pressure and isotope dependence of hyperfine structure spectra were characterized, providing important parameters for optimizing laser ionization efficiency in future experiments.
研究不足
The study was limited to tantalum and tungsten atoms in an argon gas cell, and the findings may not be directly applicable to other elements or conditions. The broad Gaussian width observed in tungsten spectra was not clearly identified, indicating potential areas for further investigation.
1：Experimental Design and Method Selection:
The study employed a two-color two-step laser resonance ionization technique using wavelengths λ1 ～ 250 nm and λ2 = 307.9 nm for excitation and ionization transitions, respectively. The methodology involved solving rate equations for populations in ground, intermediate, and ionization continuum states.
2：9 nm for excitation and ionization transitions, respectively. The methodology involved solving rate equations for populations in ground, intermediate, and ionization continuum states.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Tantalum and tungsten filaments were used to produce neutral atoms in an argon gas cell. The study focused on measuring ionization cross-sections and hyperfine structures of these elements.
3：List of Experimental Equipment and Materials:
The setup included a frequency-tunable dye laser pumped by a XeCl excimer laser for excitation, another excimer laser for ionization, and a gas cell system filled with highly purified argon gas.
4：Experimental Procedures and Operational Workflow:
The experiment involved measuring saturation curves for excitation and ionization transitions by varying photon flux densities, and analyzing hyperfine structure spectra under different argon gas pressures.
5：Data Analysis Methods:
The data were analyzed by fitting the measured spectra to Voigt functions to determine pressure shifts, broadening, and isotope shifts. Excitation and ionization cross sections were deduced from saturation curves using rate equations.
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