1. The Cs2 a3Su+, 33Sg+, and 33Pg states
Experimental study of the
Cs2 triplet states
by perturbation facilitated IR-IR double resonance
and two-photon excitation spectroscopy
The Cs2 a3Su+, 33Sg+, and 33Pg states
F. Xie, D. Li, Li Li
Tsinghua University, China
V. B. Sovkov, V. S.Ivanov
St. Petersburg State University, Russia
S. Magnier
Laboratoire de Physique des Atomes, Lasers, France

3. a3Su+ Theoretical results Te (cm-1) e (cm-1) Re (a0) De (cm-1)
This work
Jeung
Krauss
Spies
Foucrault
Weickenmeier

4. 33Sg+ 33Pg Te ωe Re De This work 17449 29.16 9.95 2754
Spies
33Pg
Spies (inner well)
(outer well)

5. Previous Experimental Results
X1Sg accurate constants (Amiot and Dulieu, JCP 117, 2002)
A1Su+ strongly pertubed by b3Pu state, preliminary constants
FTS (Verges and Amiot, JMS 126, 1978)
A-X transition frequencies -very useful for double resonance
b3Pu no observation
a3Su details
33Sg+ low resolution fluorescence
33Pg low resolution absorption

6. Two-photon study of the 33Sg+ and a3Su+ states

7. Two-photon Experimental Setup
Spex 1404
Monochromator
Photon Counting
PMT
~ 573 K 
Filters
Chopper
WA1600
l meter
PMT
DL100
Lock-in
1050 nm, 1 MHz
50 mW

8. Two-photon excitation results
50 33Sg+ v=2-9 X1Sg+ transitions
Resolved 33Sg+  a3Su+ fluorescence
Vibrational quantum numbers of the 33Sg+ levels are determined
Rotational quantum numbers are NOT determined

9. 33Sg+  a3Su+ fluorescence

11. Vibrationally resolved fluorescence

14. IR-IR Double Resonance of the 33Pg and a3Su+ states

15. The difficulties for the v, N assignment in the two-photon transitions
Lack of accurate term values of the A1Su+ and b3Pu
states
Weak 33Sg+  a3Su+fluorescence and
rotational levels of the a3Su+ state were not resolved

16. IR-IR double resonance experimental setup
Spex 1404
Monochromator
Photon Counting
PMT
~ 573 K 
Filters
WA1600
l meter
WA1600
l meter
PMT
DL100
DL100
Lock-in
1050 nm ~ 1 MHz
~ 50 mW
852 nm 1 MHz
~ 50 mW

17. The 33Pg levels observed

18. 33Pg  a3Su+ fluorescence

19. A comparison with previous absorption
The measured absorption coefficient of the Cs nm band for T=1000 K.
Our fluorescence spectrum
of Cs2, T=573 K.
T.Ban, et al., Europhys. Lett. 48 (1999), 378.

20. Rotationally resolved fluorescence

21. Summary 50 33Sg+ v=2-9  X1Sg+ two-photon transitions observed
Vibrationally resolved 33Sg+  a3Su+ fluorescence recorded
Calculated spectra are compared with observed spectra
48 ro-vibrational levels of the 33Pg state have been observed by IR-IR double resonance spectroscopy
Rotationally resolved 33Pg  a3Su+ fluorescence
Vibrational quantum numbers NOT determed
24 ro-vibrational levels of A1Su+ and b3Pu states have been confirmed for intermediate levels

22. Future Work
Resolve fluorescence to the a3Su+ and b3Pu states with FTS at Temple

23. Acknowledgement For helpful discussioms Prof. T. Bergerman
Prof. J. Huennekens
Prof. A.M. Lyyra
For helpful discussioms
NSFC for support

24. Thank You
for your attention !

25. Experimental results of the a3Su+ state
Weickenmeier et al.
observed HFS-induced X1Sg+ ~ a3Su+ mixing
derived a3Su+ constants Re=6.3 Å, ωe=11 cm-1, De=290±30 cm-1
predicted up to 50 bound levels in the well
Sainis et al.
observed the a3Su+ levels 50 cm-1 below the 4F+ 4F limit by
two-color photoassociation spectroscopy
Staanum et al.
observed the v =4-6 and levels by ultracold
atom-molecule collisions
Vatasescu et al.
identified the v =5 and 6 levels
Weickenmeier et al.
observed hfs-induced X1Sg+ ~ a3Su+ mixing
derived a3Su+ constants Re = 6.3 Å, ωe = 11 cm-1, De = 290±30 cm-1 predicted up to 50 bound levels in the well
Sainis et al.
observed the a3Su+ levels 50 cm-1 below the 4F+ 4F limit by
two-color photoassociation spectroscopy
Staanum et al.
observed the υ = 4-6 and levels by ultracold atom-molecule collisions
Vatasescu et al.
identified the υ = 5 and 6 levels
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26. A portion of the Cs2 fluorescence observed at 360 C
J. Huenneckens, Z. Wu, and T. G. Walker, Phys. Rev. A 31 (1985)
A portion of the Cs2 fluorescence observed at 360 C
33Pg a3Su+ ?
33Sg a3Su+ ?
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27. T. Ban, H. Skenderovic, R. Beuc and G. Pichler
Europhys. Lett., 48 (4), pp (1999)
Cs2 33Pg state at 543 nm
Absorption coefficient of Cs2 at 727 C
Experimental
Calculated
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