2. CONTENTS Emission Measurements Samples Preparation Fluorescence spectra Difficulties and limits Results and conclusions

3. APPARATUS – Agilent Technology Cary Eclipse Spectrophotometer METHODS EMISSION MEASUREMENTS

4. – Diluted PPO in Cyclohexane. – Diluted bisMSB in Cyclohexane. – LAB-LS (3g/L PPO + 30mg/L bisMSB) – Ultima Gold-F (UGF) – UGF-LS (LAB-LS + UG-F in 9:1 by weight) SAMPLE PREPARATION

5. PPO Back Face samples excited at 300nm Different concentrations Low concentration gives the expected primary emission using Back Face geometry More concentration; more stokes shift Self absorption

6. PPO Front Face Concentration makes small difference

7. PPO Front Face & Back Face Even concentrated sample gave primary spectrum

8. bisMSB Front Face & Back Face Method makes valuable changes

9. LAB-LS Front Face and Back Face We expect Front Face LAB-LS should show spectrum of PPO as primary emission, But it does not show, as the light can be absorbed by bisMSB also. Front Face of a liquid gives detail of its constituents depending upon the excitation range, LAB-LS shows all components.

10. Continue.… Using the same Front Face method we tried to find the primary emission of Ultima Gold-F. But unfortunately we found no fruitful results as we don’t know its constituents.

11. UGF Back Face Front Face

12. LS-UGF Green, Back Face, will reach to detector.

13. CONCLUSION Method – Self-absorption & Re-emission problem in Back Face setup. – Front Face geometry adopted. – We expect primary emission of LAB-LS will be more like PPO. Spectroscopy – We can not find Primary emission of LAB-LS or bisMSB or UG-F with photo spectrometer. – Using X-Ray spectroscopy we may find primary emission of LAB-LS and may also of Ultima Gold-F.

14. Thank you for attention….!

16. bisMSB Back Face Excited at 340nm – Low concentration is giving the expected Primary emission. – High concentration shows stoke shift.

17. Front Face bisMSB Different concentration = same expected Emission.