Resonance Enhanced TwoPhoton Ionization RE2PI Spectrum of

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Resonance Enhanced Two-Photon Ionization (RE2PI)
Spectrum of Alkali Metal Dimers

• RE2PI spectrum of RbCs near 520 nm
• 5 1S ? X 1S Transition
• Electric Quadrupole Transition of K2 near 500 nm
  
• 11Dg ? X 1Sg Transition

Y. Yoon, Y. Lee, J. Choi, S. Baek, D. Joo, and B.
Kim Korea Advanced Institute of Science and
Technology (KAIST)
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Experimental Setup
YAG laser, 355 nm
MCP
Preamplifier
Dye laser
Molecular beam
Digital Oscilloscope Board
Boxcar
Pulsed Nozzle
Skimmer
Computer
PMT
I2 Cell
NdYAG laser
Photodiode
Monitor Etalon
Dye laser
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??? ??
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RE2PI spectrum of RbCs near 520 nm 5 1S ? X 1S
Transition
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High-Resolution Spectrum and Simulation of the
260 band for 85RbCs
Simulation parameters B0?, D0? fixed, B' is
varied. laser resolution 0.02 cm-1, Tr 4.0 K.
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Molecular Constants of the 5 1S State
a D. Pavolini et al., J. Phys. B, 22, 1721
(1989) b W. Lee and Y. S. Lee (private
communication) c C. E. Fellows et al., J. Mol.
Spectrosc., 197, 19 (1999)
Vibrational Energy Spacing, DGv
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Potential Energy Curves of RbCs
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Conclusion

• The rovibrational spectra of the 5 1S state are
  observed. Molecular constants are determined.
• The potential curve of the 5 1S state is
  slightly broader because of the curve crossing of
  the 5 1S and 6 1S state.

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Electric Quadrupole Transition of K2 near 500 nm
11Dg ? X 1Sg Transition
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High-Resolution Spectrum
Simulation parameters B0?, D0? fixed, B0', D0'
varied, laser resolution 0.02 cm-1, Tr 2.8 K.
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Electric Quadrupole Transition 1Dg ?
1Sg Selection rule g ? g, u ? u, ? , ?
DL 0, ?1, ?2 DJ 0, ?1,
?2
- f e
1Dg
6 5 4 3 2
f - e
- f e
f - e
- f e
J
1Sg
4
e
Q
S
DJ
O
P
R
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Molecular Constants of the Electronic States near
500 nm
Theory S. Magnier et al., Phys. Rev. A, 54, 204
(1996)
Theoretical potential energy curves of K2
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Conclusion

• The electric-dipole forbidden transitions in K2
  are assigned to the 1 1Dg - X 1Sg transition.
• The molecular constants determined from high
  resolution spectra agree very well with
  theoretical values.

Acknowledgment
W. C. Lee and Prof. Y. S. Lee Prof. R. W. Field