Determination of Erbium by Two-Color Three-Photon Resonance Ionization Mass Spectrometry

Abstract

Excited states and autoionization states of the erbium atom were investigated by the use of multicolor resonance ionization mass spectrometry. Among the observed first excited states, a level [4f12(3H6)6s6p(3P1)] located 17,348 cm−1from the ground state is regarded as the most efficient state for excitation within the wavelength range investigated (560–600 nm), while a level located 17,080 cm−1from this first excited state (E= 34,458 cm−1) is identified as the best second excited state for the optimal photoionization scheme. Many ionization schemes adopting an autoionization state are also investigated, and the most efficient scheme is identified as 4f126s2(3H6) → 4f12(3H6)6s6p(3P10), 17,348 cm−1→ 34,458 cm−1→ continuum state, which corresponds to the two-color (ω1+ ω2+ ω1,2) scheme. Various concentrations of standard solutions for erbium are determined and the minimum amount detectable by two-color three-photon ionization was determined to be 20 pg.