1. The Submillimeter Spectrum of NdO Jennifer A. Holt Christopher F. Neese Frank C. De Lucia June 21, 2013

2. Outline Motivation Experimental Setup Production of NdO Results Future Work

3. Motivation Uranium oxide is interesting for identifying nuclear material in missile intercepts. Nd is chemically similar to Uranium, while being cheap and easier to work with. We use NdO as a substitute before moving on to UO. There is existing literature on NdO. Both optical data, and ab initio.

4. Experimental Setup

5. High Temperature Furnace Vacuum Water cooled shield Radiation Shields Furnace Tube Power Supply

6. Furnace Model Temperature profile @ 3000W input Kelvin meters

7. Furnace Evolution Shields version 1 – Composite molybdenum/stainless steel – Cheaper than using Mo for entire shield stack – Thermal model predicted safe operating temperature in region of stainless shields. Shields version 2 – Molybdenum throughout – Thinner gauge material

8. Composite Shield Failure

9. Pure Mo Shields

10. Furnace Tube Petals – Use 4 strips of tungsten brazed to copper rings. – Difficult to manufacture, warps under heat. Heat formed tungsten tube – Uses pre-fired W tube brazed to copper rings. – Pre-fired tungsten is very brittle, easy to break. Rolled Tungsten tube with Tantalum rings – Easy to manufacture, durable, used in final design. Rolled Molybdenum tube – Easier to work than tungsten, low cost alternative – Slightly lower operating temperature

11. Furnace Tubes

12. NdO Production High temperature decomposition of Nd 2 O 3 – ~2200K – Relatively benign to furnace Oxidation of metallic Nd by incidental O 2 – Starts with mixed metal and oxide – ~1600K – Highly aggressive to furnace

13. Results Large B value of ~10 GHz gives few J transitions in our tuning range, but several isotopologues and excited states result in many lines. We have good data for the ground and several excited vibronic states. Ground and first excited vibronic states are well modeled using Dunham Theory Third electronic state exhibits Ω doubling for v=0

14. Previous Work, Predictions for X, v=0, J=27, 142 NdO * Shenyavskaya, E. A. et al, 2003 Previous* This work

15. Some lines with predictions

16. Summary and Future Work Built a high temperature furnace for the production of NdO Observed spectra and improved spectroscopic constants Work on improving model of NdO Use techniques developed for NdO to take spectra of UO

17. Supplemental Slides

18. J. Chem. Phys. 124, 184317 (2006) © 2006 American Institute of Physics FIG. 1. Potential energy curves for the 13 lowest states of NdO.

19. Material Properties (W) Highest melting point metal: 3695K Very hard and brittle Difficult to work Does not spot-weld with any equipment we have Moderately expensive

20. Material Properties (Mo) Melting point 2896K Softer and more ductile than tungsten Can spot-weld with difficulty Fairly inexpensive

21. Material Properties (Ta) Melting point 3290K Very ductile and easy to work Easily spot-welds Expensive