1. Daniel P. Zaleski, Hansjochen Köckert, Susanna L. Stephens, Nick R. Walker School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK. The Pure Rotational Spectrum of PbI from Broadband Rotational Spectroscopy The Ohio State 69 th International Symposium on Molecular Spectroscopy, June 19 th, 2014. Lisa-Maria Dickens and Corey Evans Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK.

2. Introduction PbI has a 2 П 1/2 ground state Radical diatomics in this state have garnered interest in the past - SnCl - PbCl (RC07 2010 ISMS) There has been spectroscopic in the past for PbI. J. Mol. Spectrosc., 1993, 161, 552-559. Chem. Phys. Lett., 1992, 190, 271-278. J. Mol. Spectrosc., 2012, 280, 85-90. J. Mol. Spectrosc., 1998, 191, 108-116.

3. Chirped Pulse FTMW Spectroscopy Broadband spectrometers with instantaneous frequency coverage from 2-8 GHz, 6.5-18.5 GHz, 18.5-26 GHz, and 25 – 40 GHz have been constructed. Current Technology: AWG24 Gs/s (12 GHz) Digital Oscilloscope 100 Gs/s (33 GHz)

4. 600k FID’s CF 3 I, 6 bar Ar, Pb rod Dynamic Range ~10,000:1 No Coils

5. 200x 3 Primary Isotopes: 208 Pb ~52% 207 Pb ~22% 206 Pb ~24% 207 Pb spin 1/2 Exp.Theory* B (MHz) 818.2834(3)790.2489 D (kHz) 0.092(2) A (THz) |239.034| a (MHz) 186.85(5) d (MHz) 239.76(1) eQq (MHz) -701.42(5) 163.142(4) -21.0(3) * MP2/aug-cc-pVTZ-PP Chem. Phys. Lett., 1992, 190, 271-278. S/N ~50:1

6. B e = 819.3010(7) MHz α e = 2.0352(9) MHz

7. ω e = 161.02(4) cm -1 Chem. Phys. Lett., 1992, 190, 271-278. ~241 kJ/mol ω e χ e = 9690(12) MHz D E = 20003(2178) cm -1

8. 300x 3 Primary Isotopes: 120 Sn ~32% 118 Sn ~24% 116 Sn ~14% Exp.Theory* B (MHz) 1120.2711(4)1126.6139 D (kHz) 0.1608(5) A (THz) |72.19| a (MHz) 224.71(7) d (MHz) 99.96(3) eQq (MHz) -697.6(2) -143.285(2) * MP2/aug-cc-pVTZ-PP S/N ~30:1 MC-SCF

9. B e = 1121.7667(9) MHz α e = 2.991(9) MHz γ e = 0.9(5) kHz

10. ω e = 241.1(1) cm -1 ω e χ e = 16740(16) MHz D E = 25971(2823) cm -1 ~311 kJ/mol Trans. Farad. Soc.,1967, 64, 616-619.

11. Conclusions Both PbI and SnI have a 2 П 1/2 ground state Assigned a number of vibrational states for each of the Pb and Sn isotopes Modeled the PES using Morse potential E D are on the order of ~240 – 310 kJ/mol

12. Acknowledgments Engineering and Physical Sciences Research Council AWE (Aldermaston ) University of Bristol Colin Western