Determination of the first ionization potential of actinide elements by resonance ionization mass spectroscopy

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy Vol. 52; no. 6; pp. 717 - 726
• Main Authors: Köhler, S., Deiβenberger, R., Eberhardt, K., Erdmann, N., Herrmann, G., Huber, G., Kratz, J.V., Nunnemann, M., Passler, G., Rao, P.M., Riegel, J., Trautmann, N., Wendt, K.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-06-1997; Amsterdam Elsevier Science; New York, NY
• Subjects: Actinides; Atomic and molecular physics; Atomic properties and interactions with photons; Exact sciences and technology; Ionization potentials; Ionization potentials, electron affinities; Physics; Properties of atoms and atomic ions; Resonance ionization mass spectroscopy; Ionization potentials; Actinides; Resonance ionization mass spectroscopy; Resonance state; Photoionization; Atoms; Ionization potential; Mass spectroscopy; Experimental study; Inorganic element
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/S0584-8547(96)01670-9

Resonance ionization mass spectroscopy (RIMS) in the presence of an external static electric field has been used for the determination of photoionization thresholds. Extrapolation of the thresholds obtained with different electric field strengths to zero field strength directly leads to the first ionization potential (
IP). The ionization potentials of the transplutonium elements americium, curium, berkelium and californium could be measured for the first time. Due to the high sensitivity of RIMS, samples of only 10
12 atoms have been used. The results are:
IP
Am = 5.9738(2)eV,
IP
Cm = 5.9915(2)eV,
IP
Bk = 6.1979(2)eV and
IP
Cf = 6.2817(2)eV. The same technique was applied to thorium, neptunium and plutonium, yielding
IP
Th = 6.3067(2)eV,
IP
Np = 6.2655(2)eV and
IP
Po = 6.0258(2)eV. Plotted as a function of the number of electrons
N, the actinide ionization potentials can be approximated by two straight lines joining at the half-filled shell when normalized to ionization from the lowest
f
N
s
2 level to the lowest
f
N
s level.