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

a3Su+ Theoretical results Te (cm-1) e (cm-1) Re (a0) De (cm-1) This work 3371 11.58 11.91 295 Jeung 3100 11 12.07 145 Krauss 3290 11.29 11.84 282 Spies 3410 11.2 12.321 3516 11.5 11.896 Foucrault 3392 10.50 12.01 233 3479 11.86 11.92 267 Weickenmeier 3359 11 12.09 290

33Sg+ 33Pg Te ωe Re De This work 17449 29.16 9.95 2754 Spies 19500 28.8 10.10 19541 29.0 10.134 33Pg Spies 21925 (inner well) 10.199 21718 (outer well) 13.071

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

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

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

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

33Sg+  a3Su+ fluorescence

Vibrationally resolved fluorescence

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

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

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

The 33Pg levels observed

33Pg  a3Su+ fluorescence

A comparison with previous absorption The measured absorption coefficient of the Cs2 543.5nm band for T=1000 K. Our fluorescence spectrum of Cs2, T=573 K. T.Ban, et al., Europhys. Lett. 48 (1999), 378.

Rotationally resolved fluorescence

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

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

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

Thank You for your attention !

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 32-47 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 32-47 levels by ultracold atom-molecule collisions Vatasescu et al. identified the υ = 5 and 6 levels Return

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+ ? Return

T. Ban, H. Skenderovic, R. Beuc and G. Pichler Europhys. Lett., 48 (4), pp. 378-384 (1999) Cs2 33Pg state at 543 nm Absorption coefficient of Cs2 at 727 C Experimental Calculated Return