PURE ROTATIONAL SPECTRA OF THE REACTION PRODUCTS OF LASER ABLATED THORIUM METAL AND OXYGEN MOLECULES ENTRAINED WITHIN SUPERSONIC EXPANSIONS OF NOBLE GASES. *Brittany E. Long and ǂ Stephen A. Cooke RC02 June 20, 2013 * ǂ

Thorium α emitter t 1/2 = 1.4 E 10 years Solid at 25˚C MP= 1750 ˚C BP= 4820 ˚C 2

Fourier Transform Microwave Spectrometer at Wesleyan 3

Laser Ablation 4

THE MOLECULES 5

Calculations MP2 calculations with aug-cc-pVQZ for main group elements and a multi-electron, quasi-relativistic, effective core potential, ECP60MWB for thorium ThS, ThS 2, ThOC, ThOS, ThCS, For comparison reasons with HfO 2, ThO 2 was calculated with a B3LYP with aug-cc-pVQZ for O and an ECP60MWB for thorium for ThO 2 6

ThS Obtained B value from Professor Michael Heaven. B= 0.111(2) cm -1 or 3328(60) MHz 1,2 Using ν=2B(J+1) Transitions should be as follows: J 1 0 at 6656(120) MHz J 2 1 at 13312(240) MHz J 3 2 at 19968(480) MHz No ThS signal found on either the chirp or cavity with OCS or H 2 S as sulfur source. Searched 6 GHz with the chirp Searched 200 MHz twice with the cavity 1.Bartlett, J. H.; Antonov, I. O.; Heaven, M.C. Spectroscopic and Theoretical Investigations of ThS and ThS +. Manuscript in progress. 2.Bartlett, J. H.; Heaven, M. C. Ionization Measurement and Spectroscopy of ThS and ThS +. WK15 7

Measured J= 1 0 Rotational Transitions for Excited Vibrational States of ThO IsotopevFrequency/MHz 232 Th 16 O

Previous Dunham Analysis 1 ParameterValue Y 01 /MHz (35) U 01 /MHz (52) Y 11 /MHz (26) Y 21 /MHz (33) Δ O (11) eQq( 17 O) v=0 /MHz2.827(9) eQq( 17 O) v=1 /MHz2.815(9) C I ( 17 O) v=0 /MHz (5) C I ( 17 O) v=1 /MHz (5) r e BO /Å (24) 1. Dewberry, C. T.; Etchison, K. C.; Cooke, S. A. The pure rotational spectrum of actinide-containing compound thorium monoxide. Phys. Chem. Chem. Phys. 2007, 9,

ThO Vibrational Temperature Vibrational temperature≈ 3300 K ThO vibrational frequency is (2) cm -1 [1] [1] Edvinsson, G.; Selin, L. E.; Aslund, N. On the band spectrum of ThO. Arkiv Fӧr Fysik. 1965, 30,

4 Thorium Dependent Transitions Possible Quantum NumbersFrequency/ MHz Laser dependent Better signal with O 2 present Visible still in Neon Believed to be ThO 2 11

Adventures in Fitting 12 #Quantum NumbersFrequency /MHz , 2 and 31, 2 and 41, 2, 3 and 4 A (56) (42) (37) B (95) (61) (58) C (299) (141) (135) RMS /MHz P CC /amu Å

How to Proceed If ThO 2, 3 more possible transitions in range of spectrometer Currently waiting on GHz low noise amplifier Repair of 5 W solid state amplifier Quantum NumbersPredicted Frequencies/MHz

Comparisons Bond Length/ ÅBond Angle/ ˚Ground StateCitation HfO NA 1Σ1Σ1 HfO (4)107.51(1) 1 A 1 -C 2v sym.1 ThO (24)NA 1Σ1Σ2 ThO A 1 -C 2v sym.This work 1.Lesarri, A.; Suenram, R. D.; Brugh, D. Rotational spectrum of jet-cooled HfO and HfO 2. J. Chem. Phys. 2002, 117, Dewberry, C. T.; Etchison, K. C.; Cooke, S. A. The pure rotational spectrum of actinide-containing compound thorium monoxide. Phys. Chem. Chem. Phys. 2007, 9, Andrews, A.; Gong, Y.; Liang, B.; Jackson. V. E.; Flamerich, R.; Li, S.; Dixon, D. A. Matrix Infrared Spectra and Theoretical Studies of Thorium Oxide Species: ThO x and Th 2 O y. J. Phys. Chem. A. 2011, 115, (116.47˚) 14

Comparisons Continued Hf: [Xe]4f 14 5d 2 6s 2 Th: [Rn]6d 2 7s 2 <118˚ (1)˚ 15

2 nd Highest Occupied MOs 16

Conclusion Obtained the v=8-15 vibrational levels for ThO Predicted a vibrational temperature of about 3300 K Observed 4 thorium dependent transitions Most likely ThO 2 Provided interesting comparison between HfO 2 and ThO 2 Provide information via microwave spectroscopy to help advance the field of actinide chemistry 17

Future Work Finish ThO 2 Thorium with 18 O 2 and 17 O 2 as well Higher ThO vibrational levels of all species Revisit the Dunham analysis ThS and other thorium species Possible problems High omega values Out of range of spectrometers 18

Acknowledgements Novick, Pringle and Cooke Group Laboratory Funding from the DOE 19

LUMO 20

Novick Lab Picture 21