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August 13-16, 2012, Singapore

Multibubble sonoluminescence and sonochemistry of f-transition elements Pflieger R., 1 Virot M., 1 Chave T., 1 Schneider J., 2 Nikitenko S.I. , 1 1 ICSM, Marcoule, France, 2 MPI, Potsdam, Germany.

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August 13-16, 2012, Singapore

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  1. Multibubblesonoluminescence and sonochemistry of f-transition elementsPflieger R.,1Virot M.,1Chave T.,1 Schneider J.,2Nikitenko S.I.,11ICSM, Marcoule, France, 2MPI, Potsdam, Germany Institute for Separation Chemistry of Marcoule (ICSM), Laboratory of Sonochemistry in Complex Fluids (www.icsm.fr) August 13-16, 2012, Singapore

  2. Fluorescence of uranyl ions • Why U and lanthanides (Tb)? • U is a principal element of nuclearindustry • Ln are the important fission products and alsothey are widelyused in industry (catalysis, optics, medical diagnostics, etc.) Uranyl ion UO22+is a major chemicalform of uranium in aqueous solutions Absorption and emission spectra of UO22+ in 0.1M HClO4 at 25°C (used in analysis)

  3. Multifrequencyreactor for MBSL and sonochemistry

  4. Strong effect of acid In H3PO4 MBSL of UO22+ismuchstrongerthanthat in HClO4 In HClO4 UO22+exhibits extremely weak MBSL MBSL of 0.1M UO22+ in HClO4 and in H3PO at 203 kHz, 10°C, Ar. The inset shows the emission spectrum of 0.2M UO22+ in 0.2 M HClO4 after photoexcitation at λ = 427 nm.

  5. UO22+ SL intensity is strongly influenced by the ultrasonic frequency The strongest intensity of UO22+ SL is observed at 203 kHz ultrasound exhibiting the highest total SL (0.5M H3PO4, Ar)

  6. Ultrabright SL of UO22+ in H3PO4 can be seen by the unaided eye! 30 sec

  7. The differencebetween HClO4 and H3PO4isattributed to UO22+quenching Intramolecular quenching with coordinated water: (UO22+)* + H2O → UO2+ + H+ + OH• Intermolecular quenching : (UO22+)* + H2O2 → UO2+ + H+ + HO2• UO2+ + OH• (HO2•, H2O2) → UO22+ Quenching of UO22+ MBSLwith 1•10-2 M H2O2. 203 kHz, 86 W, 7.2•10-3 M UO22+ 0.5 M H3PO4, 10°C, Ar. Stable phosphate complexes UO2Hx(PO4)n+(2-3n+x) strongly decrease both intra- and intermolecular quenching

  8. Effect of UO22+ concentration – an effective tool to elucidate the mechanism of excitation SL photons are totallyabsorbed by UO22+ (>10-4 M) Contribution of collisional mechanism in concentrated solutions Sonophotoluminescence In diluted solutions

  9. MBSL of Tb(III) in aqueous solutions There is no SL of Tb(III) in diluted (<0.05 M) solutions MBSL spectra of 0.1M TbCl3 in water (11°C, Ar) Tb(III) emission ________________________ f, kHz Pac, W QY, a.u. ________________________ 20 24 0.40 203 47 0.17 607 41 0.10 PL 0.08 ________________________ Tb(III) absorption In solutions Tb(III) is excited mostly via collisional mechanism Collisional excitation is stronger at low-frequency?

  10. MBSL of Tb(III) at the extendedsolid-liquid interface Pellet (Ce0.9Tb0.1)PO4sintered pellet, water, 20 kHz, Ar, 10°C Tb(III) at the interface is excited via sonophotoluminescence mechanism

  11. CONCLUSIONS • MBSL of UO22+ is the first observation of SL for radioactive elements • MBSL of UO22+ and Tb(III) is extremely sensitive to ultrasonic frequency and to the presence of complexing reagents. • Intramolecular and intermolecular quenching strongly influence the intensity of UO22+ and Tb(III) MBSL • The mechanism of UO22+ MBSL seems to vary with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation would add its contribution at higher UO22+ concentration • MBSL of Tb(III) in solutions is triggered mostly by collisional mechanism and by sonophotoluminescence at the extended solid/liquid interface ============================== This workwassupported by French ANR program (ANR-10-BLAN-0810) NEQSON

  12. THANK YOUR FOR YOUR ATTENTION! BEST WISHES FROM THE BUBBLE TEAM OF ICSM!

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