1. Amanda Ross (WK03) Observation of the 5 1  u + and 5 1  u states of Rb 2 by polarisation labelling spectroscopy Jacek Szczepkowski, Włodzimierz Jastrzebski Institute of Physics, Polish Academy of Sciences, Warsaw Paweł Kowalczyk, Anna Grochola Institute of Experimental Physics, University of Warsaw Abdul- Rahman Allouche, Patrick Crozet and Amanda Ross Institut Lumière Matière, UMR 5306, Université Lyon1 & CNRS Just two of many excited states lying about 26000 cm -1 above the electronic ground state. PAN-CNRS €

2. Amanda Ross (WK03) Intentions A straightforward project to identify  in electronic states seen by Han & Heaven J Mol Spectrosc. 268 37 (2011). "Cold" excitation spectrum, vib. resolution, UV accessible with ns dye laser

3. Amanda Ross (WK03) Key changes in the experiment heatpipe source ~250 °C 2 colour polarisation labelling spectroscopy Work at higher J, but selectively  ', v ', ( J-1), J, (J+1) B 1  u "V" scheme X 1  g + v ", J Pump (scan) Label (fixed wavelength probe) Tuned to chosen B-X transitions

4. Amanda Ross (WK03) Polarisation spectroscopy selection rules Label X state v",J" with a fixed laser wavelength ( LABEL/PROBE ) Scan the other (Pump). Illustration for a 1  u upper state Label transition Rb 2 B 1  u – X 1  g + P(J) or R(J) Q(J) Pump lasernpolarisation Circular strong P,R Linear strong Q + weak P,R Circular nothing Linear strong Q + weak P,R Combinations can confirm assignments.

5. Amanda Ross (WK03) Experiment (IF-PAN) Excellent sensitivity (crossed polarisers + spectrograph)  Laser used to 'label' has fwhm 0.25 cm -1. Nile blue, DCM label B-X BBQ + BBD

6. Amanda Ross (WK03) Signals ? Yes. In fact, too many signals! This experiment is NOT selective. The spectra are (very) hard to assign. Supposed to show transitions from v"=1 J"=73 Pump laser with circ. polarisation Label via P(73) 7-1 B-X ??

7. Amanda Ross (WK03) Record another spectrum. Look for correlations

8. Amanda Ross (WK03) Better way to correlate spectra : take products. Multiply those two spectra. Sacrifice intensity information to some degree

9. Amanda Ross (WK03) Iterate until something emerges pump laser linear polarisation pump laser circular polarisation Both spectra labeled via R(47) 5-1 and R(47) 6-1 (products shown) cm -1

10. Amanda Ross (WK03) Quantum number assignments ? J' reasonably secure (from correlated pump transitions) v' Harder, G and F intervals not quite regular. Two similar states, 1  u + G ~31.7 cm -1 B v ~0.0158 cm -1 acceptable 1  u + G ~35.8(2) cm -1 B v ~0.0159 cm -1 messy 1  u - G ~35.1(2) cm -1 B v ~0.0164 cm -1 85 Rb 2 & 85 Rb 87 Rb observations confirm v for 1  u + FCF patterns suggest assignments for 1  u

11. Amanda Ross (WK03) Preliminary results Dunham type parameters, levels v = 2 - 20 1  u 1  u + T e 26131.4 26114.2 Y 10 35.603 31.76 Y 01 0.01590.0159 10 5 Y 11 -3.73E-05 -3.874 10 5 q 01 6.37 RMS dev.0.30.1 Compare with ab initio results : likely assignment 5 1  u and 5 1  u +

12. Amanda Ross (WK03) RKR curves show how close these states are Remarkably close to ab inito V(R) 5 1  u 5 1  u + Points : RKR curve. Lines : ab inito (A-R Allouche) Data

13. Amanda Ross (WK03) The pseudopotential CI theoretical point of view AR Allouche : extension of calculations published in JCP 136, 114302 (2012) 4 1  u + 5 1  u + 5p + 5p 5s + 6p

14. Amanda Ross (WK03) Conclusion so far. 1. The interesting parts of V(R) are not yet observed. 2. No progress at all with the original project, but those states were possibly 4 1  u and 1st well of 4 1  u +. 5 1  u + 5 1u5 1u E cm -1 28000 26000 5 10 15 20 R (A)