Polarization-based selective photoionization of ⁶⁷Zn

Isotope selective photoionization of ⁶⁷Zn is demonstrated with broadband excitation light (∼ 3.4 GHz), temporally separated laser pulses in the presence of a weak external magnetic field. Starting with natural zinc metal (∼ 4% ⁶⁷Zn) the ion sample was enriched to ∼ 90% ⁶⁷Zn. Efficient suppression of the ionization of the even-mass isotopes was achieved by intermediate state alignment in the excitation scheme 4𝑠2 ¹𝑆₀ → 4𝑠4𝑝 ³𝑃₁ → 4𝑠4𝑑 ³𝐷₁, followed by nonresonant photoionization. The first excitation pulse was linearly polarized parallel to the transverse component of the external magnetic field and the linear polarization of the second excitation pulse was rotated to compensate for Larmor precession of the quantization axis during the temporal delay between the two excitations. This is the first systematic study, in the context of resonance ionization, investigating the independent and continuous rotation of the polarizations of the excitation pulses and demonstrating efficient compensation for the presence of an external magnetic field that has an arbitrary direction. Experimental results are supported by a vector model combined with rate equations.Isotope selective photoionization of ⁶⁷Zn is demonstrated with broadband excitation light (∼ 3.4 GHz), temporally separated laser pulses in the presence of a weak external magnetic field. Starting with natural zinc metal (∼ 4% ⁶⁷Zn) the ion sample was enriched to ∼ 90% ⁶⁷Zn. Efficient suppression of the ionization of the even-mass isotopes was achieved by intermediate state alignment in the excitation scheme 4𝑠2 ¹𝑆₀ → 4𝑠4𝑝 ³𝑃₁ → 4𝑠4𝑑 ³𝐷₁, followed by nonresonant photoionization. The first excitation pulse was linearly polarized parallel to the transverse component of the external magnetic field and the linear polarization of the second excitation pulse was rotated to compensate for Larmor precession of the quantization axis during the temporal delay between the two excitations. This is the first systematic study, in the context of resonance ionization, investigating the independent and continuous rotation of the polarizations of the excitation pulses and demonstrating efficient compensation for the presence of an external magnetic field that has an arbitrary direction. Experimental results are supported by a vector model combined with rate equations.

Nov 1, 20240 citations

Polarization-based selective photoionization of 67 Zn in a weak external magnetic field

Frederick John Waso, Christine M. Steenkamp

Isotope selective photoionization of 67 Zn is demonstrated with broadband excitation light (∼3.4GHz), temporally separated laser pulses in the presence of a weak external magnetic field. Starting with natural zinc metal (∼4% 67 Zn), the ion sample was enriched to ∼90% 67 Zn. Efficient suppression of the ionization of the even-mass isotopes was achieved by intermediate state alignment in the excitation scheme 4 s 2 1 S 0 →4 s 4 p 3 P 1 →4 s 4 d 3 D 1 , followed by nonresonant photoionization. The first excitation pulse was linearly polarized parallel to the transverse component of the external magnetic field and the linear polarization of the second excitation pulse was rotated to compensate for Larmor precession of the quantization axis during the temporal delay between the two excitations. This is the first systematic study, in the context of resonance ionization, investigating the independent and continuous rotation of the polarizations of the excitation pulses and demonstrating efficient compensation for the presence of an external magnetic field that has an arbitrary direction. Experimental results are supported by a vector model combined with rate equations.Isotope selective photoionization of 67 Zn is demonstrated with broadband excitation light (∼3.4GHz), temporally separated laser pulses in the presence of a weak external magnetic field. Starting with natural zinc metal (∼4% 67 Zn), the ion sample was enriched to ∼90% 67 Zn. Efficient suppression of the ionization of the even-mass isotopes was achieved by intermediate state alignment in the excitation scheme 4 s 2 1 S 0 →4 s 4 p 3 P 1 →4 s 4 d 3 D 1 , followed by nonresonant photoionization. The first excitation pulse was linearly polarized parallel to the transverse component of the external magnetic field and the linear polarization of the second excitation pulse was rotated to compensate for Larmor precession of the quantization axis during the temporal delay between the two excitations. This is the first systematic study, in the context of resonance ionization, investigating the independent and continuous rotation of the polarizations of the excitation pulses and demonstrating efficient compensation for the presence of an external magnetic field that has an arbitrary direction. Experimental results are supported by a vector model combined with rate equations.

Applied OpticsJan 6, 20252 citations

Effect of magnetic field on isotope-selective photoionization of atomic samarium using polarized lasers

A C Sahoo, P.K. Mandal, M.L. Shah +2 more

The effect of an external magnetic field on the isotopic selectivity in a two-color three-step polarization-based isotope-selective photoionization of atomic samarium has been studied. Isotope-selective photoionization of samarium is realized through a level scheme having total angular momentum ( J ) sequence 0-1-1-continuum by using two lasers linearly polarized in the same direction and the isotopic selectivity is measured by varying the magnetic field strength perpendicular to the laser polarization axis while keeping the delay between the laser pulses fixed and vice versa. The experimental data have been analyzed and compared with the results of the numerical calculations. The magnetic field perpendicular to the laser polarization axis present in the laser-atom interaction region has been found to degrade the isotopic selectivity. Further, the Lande factor ( ) of the excited energy level 16 690.76 cm −1 ( J = 1) of samarium has been determined from the observed oscillation in the isotopic selectivity. The value of thus obtained, is in good agreement with that reported in the literature.The effect of an external magnetic field on the isotopic selectivity in a two-color three-step polarization-based isotope-selective photoionization of atomic samarium has been studied. Isotope-selective photoionization of samarium is realized through a level scheme having total angular momentum ( J ) sequence 0-1-1-continuum by using two lasers linearly polarized in the same direction and the isotopic selectivity is measured by varying the magnetic field strength perpendicular to the laser polarization axis while keeping the delay between the laser pulses fixed and vice versa. The experimental data have been analyzed and compared with the results of the numerical calculations. The magnetic field perpendicular to the laser polarization axis present in the laser-atom interaction region has been found to degrade the isotopic selectivity. Further, the Lande factor ( ) of the excited energy level 16 690.76 cm −1 ( J = 1) of samarium has been determined from the observed oscillation in the isotopic selectivity. The value of thus obtained, is in good agreement with that reported in the literature.

Journal of Physics CommunicationsOct 24, 20177 citations

Selective resonant ionization of zirconium isotopes using intermediate-state alignment

L. W. Green, G.A. McRae, Paul A. Rochefort

High selectivity (>10) for separation of $^{91}\mathrm{Zr}$ from other Zr isotopes was observed during triple resonant ionization of Zr vapors. Linearly polarized lasers were used to prepare aligned states, from which further excitation to a presently discovered J=0 level could be suppressed for even-mass isotopes, by a suitable choice of relative laser polarization. Photoionization of the odd-mass isotope $^{91}\mathrm{Zr}$ could be retained by use of transitions with relatively strong hyperfine interactions, because of associated population redistributions in the magnetic sublevels. The dependence of the even-mass-isotope signals on relative laser polarization followed sinusoidal forms, which are in excellent agreement with predictions derived using only geometric components of the transition dipole moment. The isotopic selectivity for $^{91}\mathrm{Zr}$ can be increased by use of saturating fluences, because of the effects of saturation, population trapping in the even-mass isotopes and strong hyperfine interactions in the odd-mass isotopes. For the same reasons, biases in even:odd isotope ratio measurements cannot always be eliminated by polarization scrambling or magic angles.High selectivity (>10) for separation of $^{91}\mathrm{Zr}$ from other Zr isotopes was observed during triple resonant ionization of Zr vapors. Linearly polarized lasers were used to prepare aligned states, from which further excitation to a presently discovered J=0 level could be suppressed for even-mass isotopes, by a suitable choice of relative laser polarization. Photoionization of the odd-mass isotope $^{91}\mathrm{Zr}$ could be retained by use of transitions with relatively strong hyperfine interactions, because of associated population redistributions in the magnetic sublevels. The dependence of the even-mass-isotope signals on relative laser polarization followed sinusoidal forms, which are in excellent agreement with predictions derived using only geometric components of the transition dipole moment. The isotopic selectivity for $^{91}\mathrm{Zr}$ can be increased by use of saturating fluences, because of the effects of saturation, population trapping in the even-mass isotopes and strong hyperfine interactions in the odd-mass isotopes. For the same reasons, biases in even:odd isotope ratio measurements cannot always be eliminated by polarization scrambling or magic angles.

Physical Review AJun 1, 199326 citations

Calculation of ^91Zr optical selectivities in two-color resonant three-photon ionization schemes

Pragada V. Kiran Kumar, Manda Sankari, Manda V. Suryanarayana

Optical selectivity calculations have been carried out for the 91Zr isotope for two-color resonant three-photon photoionization schemes. The density-matrix equations of motion were solved numerically for collinear, counterpropagating, linearly polarized laser beams having Gaussian temporal profile. Calculations were carried out incorporating the effects of Doppler broadening, magnetic sublevel degeneracy, and laser bandwidths. The selectivities and ion yields were determined for various Rabi frequencies and ionization rates. Thereby, the optimal Rabi frequencies for the first and second excitation steps and ionizaton rate for the ionizaton step were determined. The ionization efficiency as a function of detuning of the excitation lasers was also investigated. Two of the photoionization schemes investigated yielded a selectivity of ∼10, with an ion yield of ∼23%.Optical selectivity calculations have been carried out for the 91Zr isotope for two-color resonant three-photon photoionization schemes. The density-matrix equations of motion were solved numerically for collinear, counterpropagating, linearly polarized laser beams having Gaussian temporal profile. Calculations were carried out incorporating the effects of Doppler broadening, magnetic sublevel degeneracy, and laser bandwidths. The selectivities and ion yields were determined for various Rabi frequencies and ionization rates. Thereby, the optimal Rabi frequencies for the first and second excitation steps and ionizaton rate for the ionizaton step were determined. The ionization efficiency as a function of detuning of the excitation lasers was also investigated. Two of the photoionization schemes investigated yielded a selectivity of ∼10, with an ion yield of ∼23%.

Journal of the Optical Society of America BSep 1, 20036 citations

Isotope selective three-step photoionization of 176Lu

Manda V. Suryanarayana

Numerical computations of ionization efficiency and isotope selectivity of 176 L u have been carried out for the following three-step ladder type photoionization scheme, 5 d 6 s 2 2 D 3 / 2 ( 0.0 c m − 1 ) − − − ⟶ 540.4068 n m ⁡ 5 d 6 s 6 p 4 F 5 / 2 o ( 18504.58 c m − 1 ) − − − ⟶ 535.0626 n m 5 d 6 s 7 s 4 D 3 / 2 ( 37193.98 c m − 1 ) − − − ⟶ 618.0061 n m 53375 c m − 1 A u t o i o n i z a t i o n S t a t e → L u + , by invoking the density matrix formalism for the laser–atom interactions. Equations of motion have been derived for the odd isotopes by inclusion of hyperfine levels. The line shapes and their effect on the ionization efficiency and isotope selectivity have been discussed in detail. The effects of power of excitation and ionization lasers, spectral bandwidths, pulse delays, Doppler broadening of the atomic ensemble on the ionization efficiency, and degree of enrichment have been presented. Optimum conditions for the power of excitation, detunings, and other system parameters for the selective yet efficient photoionization of 176 L u have been identified.Numerical computations of ionization efficiency and isotope selectivity of 176 L u have been carried out for the following three-step ladder type photoionization scheme, 5 d 6 s 2 2 D 3 / 2 ( 0.0 c m − 1 ) − − − ⟶ 540.4068 n m ⁡ 5 d 6 s 6 p 4 F 5 / 2 o ( 18504.58 c m − 1 ) − − − ⟶ 535.0626 n m 5 d 6 s 7 s 4 D 3 / 2 ( 37193.98 c m − 1 ) − − − ⟶ 618.0061 n m 53375 c m − 1 A u t o i o n i z a t i o n S t a t e → L u + , by invoking the density matrix formalism for the laser–atom interactions. Equations of motion have been derived for the odd isotopes by inclusion of hyperfine levels. The line shapes and their effect on the ionization efficiency and isotope selectivity have been discussed in detail. The effects of power of excitation and ionization lasers, spectral bandwidths, pulse delays, Doppler broadening of the atomic ensemble on the ionization efficiency, and degree of enrichment have been presented. Optimum conditions for the power of excitation, detunings, and other system parameters for the selective yet efficient photoionization of 176 L u have been identified.

Journal of the Optical Society of America BNov 18, 202024 citations

High selectivity (>10) for separation of

^{91}\mathrm{Zr}

from other Zr isotopes was observed during triple resonant ionization of Zr vapors. Linearly polarized lasers were used to prepare aligned states, from which further excitation to a presently discovered J=0 level could be suppressed for even-mass isotopes, by a suitable choice of relative laser polarization. Photoionization of the odd-mass isotope

^{91}\mathrm{Zr}

could be retained by use of transitions with relatively strong hyperfine interactions, because of associated population redistributions in the magnetic sublevels. The dependence of the even-mass-isotope signals on relative laser polarization followed sinusoidal forms, which are in excellent agreement with predictions derived using only geometric components of the transition dipole moment. The isotopic selectivity for

^{91}\mathrm{Zr}

can be increased by use of saturating fluences, because of the effects of saturation, population trapping in the even-mass isotopes and strong hyperfine interactions in the odd-mass isotopes. For the same reasons, biases in even:odd isotope ratio measurements cannot always be eliminated by polarization scrambling or magic angles.