Excited-state structure and dynamics of high-energy states in lanthanide materials Mike Reid, Jon-Paul Wells, Roger Reeves, Pubudu Senanayake, Adrian Reynolds University of Canterbury Andries Meijerink, Gabriele Bellocchi University of Utrecht Giel Berden, Britta Redlich, Lex van der Meer FELIX free electron laser facility, FOM Rijnhuizen, Nieuwegein Chang-Kui Duan Chongqing University of Post and Telecommunications
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Excited-state structure and dynamics of high-energy states in lanthanide materials Mike Reid, Jon-Paul Wells, Roger Reeves, Pubudu Senanayake, Adrian Reynolds.
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Excited-state structure and dynamics of high-energy states in lanthanide materials
Mike Reid, Jon-Paul Wells, Roger Reeves, Pubudu Senanayake, Adrian ReynoldsUniversity of Canterbury
Andries Meijerink, Gabriele BellocchiUniversity of Utrecht
Giel Berden, Britta Redlich, Lex van der MeerFELIX free electron laser facility, FOM Rijnhuizen, Nieuwegein
Chang-Kui DuanChongqing University of Post and Telecommunications
Outline
4fN and 4fN-15d states.
Transitions between configurations.
Ab-inito calculations of excited-state geometry.
Spectroscopic probes of excited-state geometry.
FEL study of excitons in CaF2:Yb2+
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Reid's goal rescues Kiwis
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Lanthanide 2+/3+ ground state: 5s2 5p6 4fN 5d0
5d
4f
5s5p
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4fN and 4fN-15d
N can range from 0 to 14 Can tune the electronic structure Small interaction with surrounding ions Similar chemistry Optical Applications: 4fN
Sharp lines Long lifetimes Similar patterns in all materials So ideal for laser and phosphor applications
4fN-15d Broad absorption bands from 4fN
Useful for absorbing energy Short lifetimes useful in some applications,
such as scintillators
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Understanding the energy levels: 4fN
Coulomb Spin-orbit “Crystal-field”
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Understanding the energy levels: 4fN-15d
T2
Cubic: higher energy
ECubic:
lower energy
Crystal-field Coulomb, etc
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Absorption Emission
Stokesshift
Vibrational configurations4f
5d
Displacement [Note: may be expansion or contraction!]
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Example: Energy levels in cubic systems such as CaF2
• Cubic environment splits E and T2 orbitals
• Coulomb and spin-obit interactions adds extra structure
• Conduction band has an important influence on lifetimes