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

The Submillimeter Spectrumof NdO

Jennifer A. HoltChristopher F. Neese

Frank C. De Lucia

June 21, 2013

Outline

• Motivation• Experimental Setup• Production of NdO• Results• Future Work

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.

Experimental Setup

High Temperature Furnace

Vacuum

Water cooled shield

Radiation Shields

Furnace Tube

Power Supply

Furnace ModelTemperature profile @ 3000W input

Kelvin

meters

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

Composite Shield Failure

Pure Mo Shields

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

Furnace Tubes

NdO Production

• High temperature decomposition of Nd2O3

– ~2200K– Relatively benign to furnace

• Oxidation of metallic Nd by incidental O2

– Starts with mixed metal and oxide– ~1600K– Highly aggressive to furnace

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

Previous Work, Predictions for X, v=0, J=27, 142NdO

* Shenyavskaya, E. A. et al, 2003

Previous*This work

Some lines with predictions

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

Supplemental Slides

J. Chem. Phys. 124, 184317 (2006)© 2006 American Institute of Physics

FIG. 1. Potential energy curves for the 13 lowest states of NdO.

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

Material Properties (Mo)

• Melting point 2896K• Softer and more ductile than tungsten• Can spot-weld with difficulty• Fairly inexpensive

Material Properties (Ta)

• Melting point 3290K• Very ductile and easy to work• Easily spot-welds• Expensive