TY - JOUR
T1 - Spin-orbit coupling and vibronic transitions of two Ce(C4H6) isomers probed by mass-analyzed threshold ionization and relativistic quantum computation
AU - Zhang, Yuchen
AU - Cao, Wenjin
AU - Yang, Dong Sheng
N1 - Publisher Copyright:
© 2019 Author(s).
PY - 2019/9/28
Y1 - 2019/9/28
N2 - Ce atom reactions with ethylene, 2-butene, and isobutene are carried out in a pulsed laser vaporization molecule beam source. Ce-containing species are observed with time-of-flight mass spectrometry, and Ce(C4H6) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and relativistic quantum chemical calculations. Two structural isomers are identified for Ce(C4H6): one is the tetrahedronlike Ce[C(CH2)3] in C3v symmetry and the other is the five-membered metallocyclic Ce(CH2CHCHCH2) in Cs. The MATI spectrum of the C3v isomer exhibits two vibronic band systems separated by 88 cm-1, while that of the Cs isomer displays three split by 60 and 101 cm-1. The multiple band systems are attributed to spin-orbit splitting and vibronic transitions involving metal-hydrocarbon and hydrocarbon-based vibrations. The splitting in the C3v isomer arises from interactions of two triplet and two singlet states at the lowest energies, while each splitting in the Cs isomer involves two triplets and a singlet. Although the Ce atom has ground electron configuration 4f15d16s2, Ce valence electron configurations in both isomers are 4f16s1 in the neutral ground state and 4f1 in the ion. The remaining Ce 5d electrons in the isolated atom are spin paired in molecular orbitals that are a bonding combination between Ce 5dπ and hydrocarbon π∗ orbitals.
AB - Ce atom reactions with ethylene, 2-butene, and isobutene are carried out in a pulsed laser vaporization molecule beam source. Ce-containing species are observed with time-of-flight mass spectrometry, and Ce(C4H6) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and relativistic quantum chemical calculations. Two structural isomers are identified for Ce(C4H6): one is the tetrahedronlike Ce[C(CH2)3] in C3v symmetry and the other is the five-membered metallocyclic Ce(CH2CHCHCH2) in Cs. The MATI spectrum of the C3v isomer exhibits two vibronic band systems separated by 88 cm-1, while that of the Cs isomer displays three split by 60 and 101 cm-1. The multiple band systems are attributed to spin-orbit splitting and vibronic transitions involving metal-hydrocarbon and hydrocarbon-based vibrations. The splitting in the C3v isomer arises from interactions of two triplet and two singlet states at the lowest energies, while each splitting in the Cs isomer involves two triplets and a singlet. Although the Ce atom has ground electron configuration 4f15d16s2, Ce valence electron configurations in both isomers are 4f16s1 in the neutral ground state and 4f1 in the ion. The remaining Ce 5d electrons in the isolated atom are spin paired in molecular orbitals that are a bonding combination between Ce 5dπ and hydrocarbon π∗ orbitals.
UR - http://www.scopus.com/inward/record.url?scp=85072756852&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85072756852&partnerID=8YFLogxK
U2 - 10.1063/1.5123729
DO - 10.1063/1.5123729
M3 - Article
C2 - 31575165
AN - SCOPUS:85072756852
SN - 0021-9606
VL - 151
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 12
M1 - 124307
ER -