Energy levels of Th+ between 7.3 and 8.3 eV

Abstract

Using resonant two-step laser excitation of trapped 232Th+ ions, we observe 43 previously unknown energy levels within the energy range from 7.3 to 8.3 eV. The high density of states promises a strongly enhanced electronic bridge excitation of the 229mTh nuclear state that is expected in this energy range. From the observation of resonantly enhanced three-photon ionization of Th+, the second ionization potential of thorium can be inferred to lie within the range between 11.9 and 12.3 eV. Pulsed laser radiation in a wide wavelength range from 237 to 289 nm is found to provide efficient photodissociation of molecular ions that are formed in reactions of Th+ with impurities in the buffer gas, leading to a significantly increased storage time for Th+ in the ion trap.

7 pages, 6 figures

References in corpus (7)

• Wigner Crystals of 229Th for Optical Excitation of the Nuclear Isomer
• Excitation of the isomeric ^{229m}Th nuclear state via an electronic bridge process in ^{229}Th^+
• Electronic bridge process in 229Th^+
• Laser ablation loading of a radiofrequency ion trap
• Two-photon laser excitation of trapped 232Th+ ions via the 402 nm resonance line
• Exponential increase of energy level density in atoms: Th and Th II
• Charge Exchange and Chemical Reactions with Trapped Th${}^{3+}$

Cited by in corpus (16)

• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• Nuclear clocks based on resonant excitation of gamma-transitions
• Radiative lifetime and energy of the low-energy isomeric level in ${}^{229}$Th
• Precision spectroscopy by photon-recoil signal amplification
• On the Validity of Steady-State for Nebular Phase Kilonovae
• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• On an attempt to optically excite the nuclear isomer in Th-229
• Radioluminescence and photoluminescence of Th:CaF${}_2$ crystals
• Trapping and sympathetic cooling of single thorium ions for spectroscopy
• Relativistic all-order calculations of Th, Th${}^{+}$ and Th${}^{2+}$ atomic properties
• Measuring the Th-229 nuclear isomer transition with U-233 doped crystals
• Observation of an unexpected negative isotope shift in 229Th+ and its theoretical explanation
• Electronic level structure of ${\mathrm{Th}}^{+}$ in the range of the ${}^{229m}\mathrm{Th}$ isomer energy
• Generation of vacuum ultraviolet radiation by intracavity high-harmonic generation toward state detection of single trapped ions
• Studies of thorium and ytterbium ion trap loading from laser ablation for gravity monitoring with nuclear clocks
• High-resolution laser system for the S3-Low Energy Branch