Manda Sankari, Pragada V. Kiran Kumar, and Manda V. Suryanarayana, "Investigations on the 1S0 λ1→ 1P01 λ2→ 1S0 nonresonant——→ M+ photoionization pathway for selective ionization of rare calcium and strontium isotopes," J. Opt. Soc. Am. B 21, 1369-1378 (2004)
Optical selectivities have been calculated by use of the density matrix approach for
double-resonance photoionization pathways to establish the possibility of selective ionization of rare calcium and strontium isotopes for continuous-wave laser excitation. Numerical integration of the density matrix equations for double-resonance ionization has been carried out by incorporation of the effects of Doppler broadening, velocity-dependent interaction times, time-varying Rabi frequencies, and laser bandwidths. The conditions for obtaining optimum selectivities have been evaluated. This study results in five new photoionization pathways (two for calcium and three for strontium) whose optical selectivities were found to be a few orders higher than the previously studied photoionization schemes. The effect of laser linewidth of the excitation lasers and Doppler width have also been investigated.
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Both lasers are considered to be monochromatic, full angular divergence of the atomic beam is 1.5°, and the ionization rate is considered to be 8.4 kHz.
Uncertainties that arise from isotope shifts are in parentheses.
Table 4
Effect of Linewidth of Excitation Lasers on the Optical Selectivity for the Photoionization Schemes Studieda
Linewidth of both excitation lasers is considered to be equal, full angular divergence of the atomic beam is 1.5°, and the ionization rate is considered to be 8.4 kHz.
Uncertainties that arise from isotope shifts are in parentheses.
Table 5
Effect of Full Angle Divergence (θ) on Optical Selectivity for the Photoionization Schemes Studieda
Both excitation lasers are considered to be monochromatic, and the ionization rate is considered to be 8.4 kHz.
Uncertainties that arise from isotope shifts are in parentheses.
Table 6
Frequency Position of the Incoherent Excitation Peak for All the Photoionization Schemes Investigated
Element
(nm)
Position of Incoherent Excitation Peak (MHz)
Ca
586.9
-112
551.5
-119
Sr
1124.1
+84
767.3
+124
597.0
+159
516.5
+184
Tables (6)
Table 1
Decay Rates for the Levels Relevant to the Investigated Photoionization Schemes for Ca and Sr
Isotope
Upper Level
Lower Level
Decay Rate (MHz)
Ca
224.0
30.62
112.5
0.0003141
2.537
Sr
215.00
3.79
3.19
0.017
15.6
21.6
18.6
9.28
0.009
47.20
7.44
2.67
1.08
5.59
2.67
0.71
0.033
1.92
Table 2
Isotope Shift and Resonance Position of the Most Intense Hyperfine Component (for Ca) for the Photoionization Schemes Studied
Calcium
Strontium
Transition
Isotope Shift of (Relative to (MHz)
Resonance Frequency Position of the Most Intense Hyperfine Component of (Relative to (MHz)
Both lasers are considered to be monochromatic, full angular divergence of the atomic beam is 1.5°, and the ionization rate is considered to be 8.4 kHz.
Uncertainties that arise from isotope shifts are in parentheses.
Table 4
Effect of Linewidth of Excitation Lasers on the Optical Selectivity for the Photoionization Schemes Studieda
Linewidth of both excitation lasers is considered to be equal, full angular divergence of the atomic beam is 1.5°, and the ionization rate is considered to be 8.4 kHz.
Uncertainties that arise from isotope shifts are in parentheses.
Table 5
Effect of Full Angle Divergence (θ) on Optical Selectivity for the Photoionization Schemes Studieda
Both excitation lasers are considered to be monochromatic, and the ionization rate is considered to be 8.4 kHz.
Uncertainties that arise from isotope shifts are in parentheses.
Table 6
Frequency Position of the Incoherent Excitation Peak for All the Photoionization Schemes Investigated