Ionization yield and isotopic selectivity of three-step photoionization of atoms by pulsed lasers

Gupta, Gaurav; Suri, B. M.

doi:10.1088/0022-3727/35/12/306

Cited by 3 publications

(2 citation statements)

References 22 publications

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“…laser pulse width is much larger as compared to its coherence time which is equal to the inverse of the laser line width and hence, transition between different optical energy levels is incoherent. In such cases multi-step photoexcitation dynamics can be described by rate equations [31].…”

Section: Numerical Calculationsmentioning

confidence: 99%

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

et al. 2017

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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. Isotopeselective 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 (g J ) 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 g , J thus obtained, is in good agreement with that reported in the literature.

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Section: Numerical Calculationsmentioning

confidence: 99%

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

et al. 2017

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“…In the case of broadband lasers, the interaction time is much larger as compared to its coherence time which is equal to the inverse of the laser linewidth and, hence, the laser-atom interaction is incoherent [24]. In such cases, multi-step photoexcitation dynamics can be described by simple population rate equations instead of more complex density matrix equations [23,24]. The population rate equations for three-step photoionization, depicted in Fig.…”

Section: Theoretical Analysis 31 Population Rate Equationsmentioning

confidence: 99%

Understanding photoexcitation dynamics in a three-step photoionization of atomic uranium and measurement of photoexcitation and photoionization cross sections

et al. 2015

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accessible with the conventional spectroscopic techniques such as absorption and emission spectroscopy, and in many laser-based applications such as isotope-selective photoionization processes, elemental ultra-trace analysis, etc. [8][9][10][11]. For the effective implementation of the processes mentioned above, identification of an efficient multi-step photoionization scheme is a prerequisite [1,11,12]. Precise information on photoexcitation and photoionization cross sections is necessary in the selection of an efficient multi-step photoionization scheme. It also helps in the distribution of the available tunable laser powers between various steps for efficient photoionization of atom.Several laser-based methods such as transition saturation [1,9,12], branching ratio and life time [12][13][14][15][16], Rabi oscillations [12], Autler-Towns [12,17] are reported in the literature by various research groups worldwide for the measurement of photoexcitation cross sections. With the exception of Mclaughlin et al. [18] who have measured the absolute photoionization cross section of Ti from the second excited level by observing the depletion in the fluorescence signal, the saturation method is the most suitable for the measurement of photoionization cross section [19][20][21][22]. The saturation in the photoionization signal represents the complete transfer of atomic population from the last excited level in the stepwise photoionization scheme. In this method, one has the advantage of measuring photoexcitation and photoionization cross sections using the same apparatus.The ionization potential of uranium is ~6.19 eV. Hence, a three-step photoionization of atomic uranium is the most appropriate using visible lasers whose photon energy is ~2 eV. In a three-color three-step photoionization process, i.e., λ 1 + λ 2 + λ 3 , where two-color photoionization, i.e., λ 1 + 2λ 2 , as shown in Fig. 1a, is not possible, photoexcitation and photoionization cross sections of the transitions used in a scheme are measured by observing saturation in Abstract Photoexcitation dynamics in a three-step photoionization of atomic uranium has been investigated using time-resolved two-color three-photon and delayed threecolor three-photon photoionization signals. Investigations are carried out in an atomic beam of uranium coupled to a high-resolution time-of-flight mass spectrometer using three tunable pulsed dye lasers. Dependence of both the signals on the second-step laser photon fluence is studied. Excited-level-to-excited-level photoexcitation cross section and photoionization cross section from the second excited level are simultaneously determined by analyzing the two-color three-photon and three-color three-photon photoionization signals using population rate equation model. Using this methodology, photoexcitation and photoionization cross sections at seven values of the second-step laser wavelength have been measured. From the measured values of the photoexcitation cross sections, we have obtained excited-level-to-excited-level transiti...

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Even-parity autoionizing levels of atomic uranium and their total angular momenta

et al. 2017

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Ionization yield and isotopic selectivity of three-step photoionization of atoms by pulsed lasers

Cited by 3 publications

References 22 publications

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

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

Understanding photoexcitation dynamics in a three-step photoionization of atomic uranium and measurement of photoexcitation and photoionization cross sections

Even-parity autoionizing levels of atomic uranium and their total angular momenta

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