High efficiency resonance ionization of palladium with Ti:sapphire lasers

Kron, T.; Liu, Yuan; Richter, Sven; Schneider, F.; Wendt, Κ.

doi:10.1088/0953-4075/49/18/185003

Cited by 18 publications

(11 citation statements)

References 19 publications

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“…Beyond silver, our combination of techniques can be used to study other elements in the N = Z region near 100 Sn. Cross-section calculations, validated by experiments at the GSI Helmholtzzentrum für Schwerionenforschung 7 , 21 , 46 – 50 , together with high laser ionization efficiencies 51 , 52 and our primary beam intensities suggest 93 Pd, 97 Cd, 100 In, and 101 Sn are within reach, as highlighted in Fig. 3 .…”

Section: Discussionsupporting

confidence: 69%

Evidence of a sudden increase in the nuclear size of proton-rich silver-96

Reponen

Groote

et al. 2021

Nat Commun

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Understanding the evolution of the nuclear charge radius is one of the long-standing challenges for nuclear theory. Recently, density functional theory calculations utilizing Fayans functionals have successfully reproduced the charge radii of a variety of exotic isotopes. However, difficulties in the isotope production have hindered testing these models in the immediate region of the nuclear chart below the heaviest self-conjugate doubly-magic nucleus 100Sn, where the near-equal number of protons (Z) and neutrons (N) lead to enhanced neutron-proton pairing. Here, we present an optical excursion into this region by crossing the N = 50 magic neutron number in the silver isotopic chain with the measurement of the charge radius of 96Ag (N = 49). The results provide a challenge for nuclear theory: calculations are unable to reproduce the pronounced discontinuity in the charge radii as one moves below N = 50. The technical advancements in this work open the N = Z region below 100Sn for further optical studies, which will lead to more comprehensive input for nuclear theory development.

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Section: Discussionsupporting

confidence: 69%

Evidence of a sudden increase in the nuclear size of proton-rich silver-96

Reponen

Groote

et al. 2021

Nat Commun

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“…For assignment of the energy levels, we use the J c K coupling scheme [20] which is appropriate for Pd I. Selection rules for the transition from the 4d 9 6 s state indicate eight Rydberg series are expected, five of which are autoionizing: Fig. 4 Observed ion current in the two different odd-mass isotope selectivity schemes.…”

Section: Resultsmentioning

confidence: 99%

Improved efficiency of selective photoionization of palladium isotopes via autoionizing Rydberg states

2016

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are only approximately 50 MHz [2], it is not feasible to selectively ionize isotopes using narrow linewidth lasers; however, two effective techniques exist for selective ionization. The first is based on a proposal by Balling and Wright [1] using circularly polarized lasers, in which only odd-mass number isotopes having nonzero nuclear spin and thus having hyperfine structure are able to be excited due to optical transition selection rules. The feasibility of this scheme as applied to platinum group metals is reported by Chen [3], implemented by Yamaguchi and Sasao [4, 5], and further developed in our previous paper [6]. The second technique, resonant ionization mass spectrometry (RIMS) [7, 8], obtains selectivity of ionized isotopes via a narrow slit and accelerating fields, such as the RISIKO separator system as applied to palladium [9]. Comparison between the efficiencies and costs of both techniques are essential before commercial-scale projects can be undertaken. We have developed our apparatus employing the first technique, that is, exploiting transition rules for selective excitation [10]. Resonant excitation to autoionizing states is a promising means to obtain efficient ionization after such mass-selective excitation. Autoionizing Rydberg states come about due a characteristic in the spin-orbit interaction of Pd, where the ion Pd II has two ground states of different ion core configurations, namely 4d 9 (2 D 5/2) at 67241.3(8) cm −1 and 4d 9 (2 D 3/2) at 70779.8(8) cm −1 [11]. Any states existing between the two ground states are autoionizing, and the ion yield is over an order of magnitude higher than excitation to the ionization continuum [12]. The conventional Pd odd-mass selectivity excitation scheme excites via intermediate states having a 2 D 5/2 core [3-6], as shown as configuration (a) in Fig. 1. For this scheme, selectivity is obtained via (0-1-0) transition rules, that is, the first level is J = 0, the first intermediate state is J = 1, and the second intermediate state is J = 0. If Abstract Odd-mass-selective ionization of palladium for purposes of resource recycling and management of long-lived fission products can be achieved by exploiting transition selection rules in a well-established three-step excitation process. In this conventional scheme, circularly polarized lasers of the same handedness excite isotopes via two intermediate 2 D 5/2 core states, and a third laser is then used for ionization via autoionizing Rydberg states. We propose an alternative excitation scheme via intermediate 2 D 3/2 core states before the autoionizing Rydberg state, improving ionization efficiency by over 130 times. We confirm high selectivity and measure odd-mass isotopes of >99.7(3)% of the total ionized product. We have identified and measured the relative ionization efficiency of the series of Rydberg states that converge to upper ionization limit of the 4d 9 (2 D 3/2) level, and identify the most efficient excitation is via the Rydberg state at 67668.18(10) cm −1 .

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“…The layout of the laser cavities and the overall setup including shaping, transport, overlap and spectral, spatial and temporal control of the laser beams is based on experiences from a number of widely similar laser systems utilized for atomic spectroscopy, for production of isotopically pure ion beams at radioactive ion beam facilities and for different applications of trace analyses. 6 The setup consists of three tunable Ti:sapphire lasers, delivering up to 4 W laser power each at a repetition rate of 10 kHz with 5-9 GHz spectral bandwidth. The Ti:sapphire lasers are pumped independently by three frequency doubled, commercial Nd:YAG lasers.…”

Section: Ti:sapphire Laser System For Resonance Ionizationmentioning

confidence: 99%