1. CALIFORNIA INSTITUTE OF TECHNOLOGY 68th International Symposium on Molecular Spectroscopy - June 19, 2013 A LOW-COST CHIRPED-PULSE FOURIER TRANSFORM MICROWAVE SPECTROMETER FOR UNDERGRADUATE PHYSICAL CHEMISTRY LAB Brandon Carroll  Ian A. Finneran  Geoffrey A. Blake

2. STARK SPECTROMETER Hewlett-Packard Journal

3. STARK SPECTROMETER Hewlett-Packard Journal June1971

4. INTRODUCTION

5. ROTATIONAL SPECTRUM OF OCS

7. J = 1 J = 0 F = 3/2 F = 5/2 F = 3/2 F = 1/2 F = 5/2 F = 3/2 eqQ = 0eqQ > 0eqQ < 0 -0.25 eqQ -0.05 eqQ +0.20 eqQ -0.25 eqQ -0.05 eqQ +0.20 eqQ

8. ROTATIONAL SPECTRUM OF OCS J = 1 J = 0 F = 3/2 F = 5/2 F = 3/2 F = 1/2 F = 5/2 F = 3/2 eqQ = 0eqQ > 0eqQ < 0 -0.25 eqQ -0.05 eqQ +0.20 eqQ -0.25 eqQ -0.05 eqQ +0.20 eqQ

9. ROTATIONAL SPECTRUM OF OCS J = 1 J = 0 F = 3/2 F = 5/2 F = 3/2 F = 1/2 F = 5/2 F = 3/2 eqQ = 0eqQ > 0eqQ < 0 -0.25 eqQ -0.05 eqQ +0.20 eqQ -0.25 eqQ -0.05 eqQ +0.20 eqQ

10. CP-FTMW 30 seconds

11. CP-FTMW ISMS 2013 WH07

12. CP-FTMW ISMS 2013 WH07

13. CP-FTMW

14. CP gives all the same information –Cover 11 GHz – 12 GHz –Detect 16 O 12 C 32 S, 16 O 12 C 34 S, 16 O 13 C 32 S, 16 O 12 C 33 S Time domain spectroscopy Coherence Simple analysis Strong links to other experiments (NMR, EPR) Can be done inexpensively UNDERGRADUATE CP-FTMW

15. CP gives all the same information –Cover 11 GHz – 12 GHz –Detect 16 O 12 C 32 S, 16 O 12 C 34 S, 16 O 13 C 32 S, 16 O 12 C 33 S Time domain spectroscopy Coherence Simple analysis Strong links to other experiments (NMR, EPR) Can be done inexpensively UNDERGRADUATE CP-FTMW

16. INSTRUMENT DIAGRAM X Band Waveguide Stark cell SPST Switch

17. INSTRUMENT DIAGRAM X Band Waveguide Stark cell SPST Switch

18. PARTS

19. Tunable 11.2 – 13.1 GHz Phase moderately stable $ 150 PLL VCO

20. 6 -18 GHz $200 - $1300 Enclosed, simple Reasonable noise figure, power Robust RF AMPLIFIERS AND MIXERS

21. Simple programming Moderate timing jitter (~100ns) Controls AD9914 automatically Multiple output channels TIMING I/O

22. Linear frequency ramps 0 – 2 GHz Phase stable Tunable, stepped LO source $ 600 DDS

23. Linear frequency ramps 0 – 2 GHz Phase stable Tunable, stepped LO source $ 600 DDS

25. 200 MHz Bandwidth 1 GS/s > 1kHz acquisition Onboard FFT, including windowing 60,000 Waveform memory $1575 OSCILLOSCOPE

26. SPECTROMETER

27. 16 O 12 C 32 S 50,000 averages

28. 16 O 12 C 34 S 100,000 averages

29. 16 O 13 C 32 S 500,000 averages

30. 16 O 12 C 33 S 1 million averages

31. 16 O 12 C 33 S 1 million averages 15 minutes!

32. 16 O 12 C 32 S COHERENCE

33. PARTS LIST

34. Design is extremely versatile Can be adapted to multiple experimental designs Applicable to numerous molecular systems Research applications Lots more to come Instructions available at http://www.gps.caltech.edu/~gab/resources. html CONCLUSIONS

35. ACKNOWLEDGEMENTS Blake Lab: -Marco Allodi -Brett McGuire -Sergio Ioppolo -Xander de Vries -Jacob Good - Nate Crockett -Masha Klescheva -Coco Zhang -Dana Anderson -Katherine Kaufman -Alex Lockwood Caltech: -Daniel Thomas -Jack Beauchamp -Dan Weitekamp