1. Christopher F. Neese and Frank C. De Lucia, Department of Physics, The Ohio State University 191 W. Woodruff Ave., Columbus, OH 43210 USA Ivan R. Medvedev Department of Physics, Wright State University 3640 Colonel Glenn Hwy, Dayton, OH 45435. Sensors Across the Spectrum

3. What is a spectroscopic sensor?

4. Complex design space Cost Required frequency precision Size, weight, power Cell path length Support hardware Vacuum system, preconcentrators, computers, etc. Specificity Sensitivity Speed and agility Duty cycle Target analytes

5. Constraints Samples in equilibrium at room temperature Goal is to provide a specific test Gas phase Narrowband sources

6. Line Intensity

7. Three pressure regimes

9. Where is the signature?

10. Intensity Envelope

11. Intensity Envelope (a-type)

12. Intensity Envelope (c-type)

13. Intensity Envelope (b-type)

14. Where is the rotational signature? linear or symmetric top a-type lines of asymmetric top b-type lines of asymmetric top c-type lines of asymmetric top

15. Mid IR – THz comparison (HITRAN)

16. What is the noise?

17. Pre-concentration Well-established technology for GC Preconcentration factors of up to 10 5 Well-matched to SMM/THz where optimal pressure is 10 -5 atm.

18. Conclusions The best way to compare two sensors is to begin with a mission. Comparing the THz/SMM to the IR is a tie.