1. AUSTIN L. MCJUNKINS, K. MICHELLE THOMAS, APRIL RUTHVEN, AND GORDON G. BROWN Department of Science and Mathematics, Coker College, 300 E College Ave., Hartsville, SC 29550. MH10 ROOM-TEMPERATURE CHIRPED-PULSE FOURIER TRANSFORM MICROWAVE (RT-CP-FTMW) SPECTRUM OF PYRIDINE

2. Outline  Inexpensive room-temperature chirped- pulse Fourier transform (RT-CP-FTMW) microwave spectrometer  Benchmark test - methanol  Room-Temperature spectrum of pyridine

3.  Ideally suited for primarily undergraduate institution (PUI) Inexpensive ($30 - $50K) No moving parts (easy to build and use) Useful for undergraduate research and teaching labs Inexpensive Room-Temperature Chirped-Pulse Fourier transform (RT-CP-FTMW) Microwave Spectrometer

4. MW Synthesizer ν0ν0 Fourier Transform Oscilloscope (1 GHz) Chirped-Pulse Arbitrary Function Generator (240 MHz) molecular FID static cell (12 feet of WRD-750 waveguide) to vacuum mixer power divider amplifier Diode limiter 1 S. T. Shipman, J. L. Neill, B. Kroncke, B. H. Pate, and P. Groner, Presentation at the International Symposium on Molecular Spectroscopy, Columbus, OH, USA, 2008. 2 Z. Kisiel, O. Dorosh, A. Maeda, I. R. Medvedev, F. C. De Lucia, E. Herbst, B. J. Drouin, J. C. Pearson, S. T. Shipman, Phys. Chem. Chem. Phys., 2010, 12, 8329-8339. ~480 MHz chirped pulse 1W solid- state amp Inexpensive Room-Temperature Chirped-Pulse Fourier transform (RT-CP-FTMW) Microwave Spectrometer

5. MW Synthesizer ν0ν0 Fourier Transform Oscilloscope (1 GHz) Chirped-Pulse Arbitrary Function Generator (240 MHz) molecular FID static cell (12 feet of WRD-750 waveguide) to vacuum * Garry S. Grubbs II, Christopher T. Dewberry, Kerry C. Etchison, Katherine E. Kerr, and Stephen A. Cooke, Rev. Sci. Instrum., 2007, 78, 096106. ~480 MHz chirped pulse 1W solid- state amp double sideband mixer* diode limiter Advanced Control Components ACLM- 4619FC36 Inexpensive Room-Temperature Chirped-Pulse Fourier transform (RT-CP-FTMW) Microwave Spectrometer

6. 240 MHz Chirped Pulse before power amplifier

7. Our spectrometer

8. Outline  Inexpensive room-temperature chirped- pulse Fourier transform (RT-CP-FTMW) microwave spectrometer  Benchmark test - methanol  Room-Temperature spectrum of pyridine

9. you never forget your first… Methanol 2 02 – 3 -13 (12178.60 MHz) (on cheap oscilloscope)

10. Benchmark: Methanol 16 5 12 17 4 13 2 0 2 3 -1 3 5 1 5 4 1 4 v 0 = 12300MHz white spectrum v 0 = 12304 MHz gold spectrum For 2 0 2 3 -1 3 : 12300 – 121.4 = 12178.6 MHz 12304 – 125.4 = 12178.6 MHz

11. Benchmark: Methanol Assignment Previous Observation (MHz) 2 Shipman et al observation (MHz) 1 Current Work (MHz) 16 5 12 – 17 4 13 12229.40012229.35412229.36 2 02 – 3 -13 12178.59312178.59912178.60 5 14 - 5 15 12511.00012511.20312511.19 1 S. T. Shipman, J. L. Neill, B. Kroncke, B. H. Pate, and P. Groner, Presentation at the International Symposium on Molecular Spectroscopy, Columbus, OH, USA, 2008. 2 L. H. Xu and F. J. Lovas, J. Phys. Chem. Ref. Data, 1997, 26, 17.

12. Outline  Inexpensive room-temperature chirped- pulse Fourier transform (RT-CP-FTMW) microwave spectrometer  Benchmark test - methanol  Room-Temperature spectrum of pyridine

13. Previous MW work on Pyridine 1,2  G. O. Sørensen: MW spectrum 8.5 – 27 GHz @ 25 ºC and -20 ºC 1 Ground vibrational state Quadrupole Coupling Constants  Ye et al.: 75 – 110 GHz and 260 – 370 GHz Improved constants for ground state Assigned 6 vibrationally excited states 1 G. O. Sørensen, J. Molec. Spectr., (1967) 22, 325-346. 2 Enyi Ye, Ryan P.A. Bettens, Frank C. DeLucia, Douglas T. Petkie, and Sieghard Albert, J. Molec. Spectr., (2005) 232, 61-65.

14. Room-Temp Spectrum of Pyridine 1,2 10,000 averages; ~5 mTorr; 25 ºC ~ 10 sec/step, 35 (overlapping) steps

15. Room-Temp Spectrum of Pyridine Ground Vibrational State 1 G. O. Sørensen, J. Molec. Spectr., (1967) 22, 325-346. J” Ka” Kc” J’ Ka’ Kc’ Frequency (MHz) Previous Work(MHz) 1 4 4 1 4 2 2 10288.62 11 9 2 11 9 3 10383.00 32 27 5 32 27 6 10569.50 5 5 1 5 3 2 11164.00 38 32 6 38 32 7 11269.00 10 8 2 10 8 3 11398.50 25 21 4 25 21 5 11444.00 18 15 3 18 15 4 11491.50 44 37 7 44 37 8 11762.91 9 7 2 9 7 3 12301.5012301.49 6 6 1 6 4 2 12342.0012341.19 31 26 5 31 26 6 12621.00 17 14 3 17 14 4 12990.00 8 6 2 8 6 3 13070.00 24 20 4 24 20 5 13297.5013297.44 37 31 6 37 31 7 13535.0413535.32 7 5 2 7 5 3 13688.00 7 7 1 7 5 2 13861.0013860.48 6 4 2 6 4 3 14149.50 43 36 7 43 36 8 14214.0214213.58 16 13 3 16 13 4 14419.50 5 3 2 5 3 3 14464.0014463.96 4 2 2 4 2 3 14655.0015654.68 2 1 2 1 1 1 14682.5014682.62 J” Ka” Kc” J’ Ka’ Kc’ Frequency (MHz) Previous Work(MHz) 1 3 1 2 3 1 3 14753.62 30 25 5 30 25 6 14765.0014764.75 3 2 2 3 0 3 14823.0014823.27 4 3 2 4 1 3 14863.30 2 0 2 1 0 1 14902.5014903.13 5 4 2 5 2 3 14948.0014947.33 6 5 2 6 3 3 15100.50 23 19 4 23 19 5 15153.0015153.20 7 6 2 7 4 3 15356.00 15 12 3 15 12 4 15740.5015740.47 8 8 1 8 6 2 15744.5015743.01 8 7 2 8 5 3 15755.0015755.21 36 30 6 36 30 7 15933.7815933.90 9 8 2 9 6 3 16346.00 42 35 7 42 35 8 16834.8216834.51 14 11 3 14 11 4 16920.50 29 24 5 29 24 6 16943.00 22 18 4 22 18 5 16960.50 10 9 2 10 7 3 17183.59 48 40 8 48 40 9 17480.38 13 10 3 13 10 4 17932.00 9 9 1 9 7 2 17992.00 11 10 2 11 8 3 18322.50 35 29 6 35 29 7 18403.50

16. Room-Temp Spectrum of Pyridine Ground Vibrational State Spectroscopic Constant Sorensen work 1 Ye et al work 2 Current work* 1 Current work* 2 A (MHz)6039.2446039.24436039.086039.09 B (MHz)5804.9035804.91385804.725804.74 C (MHz)2959.2202959.210012959.182959.19 Δ J (kHz)-0.0111.3897-0.011*1.3897* Δ JK (kHz)-2.252-2.4984-1.18 Δ K (kHz)1.6951.22781.26 δ J (kHz)-0.00704 δ K (kHz)-2.0074 N lines 52118546 1 G. O. Sørensen, J. Molec. Spectr., (1967) 22, 325-346. 2 Enyi Ye, Ryan P.A. Bettens, Frank C. DeLucia, Douglas T. Petkie, and Sieghard Albert, J. Molec. Spectr., (2005) 232, 61-65. * Δ J values fixed to those of previous work.

17. Room-Temp Spectrum of Pyridine First Excited Vibrational State 1 G. O. Sørensen, J. Molec. Spectr., (1967) 22, 325-346. J” Ka” Kc” J’ Ka’ Kc’ Frequency (MHz) Previous Work(MHz) 1 10 8 2 10 8 3 11515.50 6 4 2 6 4 3 14153.50 16 13 3 16 13 4 14708.00 2 0 2 1 0 1 14907.00 6 5 2 6 3 3 15051.50 15 12 3 15 12 4 15979.13 14 11 3 14 11 4 17106.00 22 18 4 22 18 5 17490.10 13 10 3 13 10 4 18067.00 11 10 2 11 8 3 18077.00 Spectroscopic Constant Ye et al work 2 Current work A (MHz)6032.36966032.44 B (MHz)5805.20815805.23 C (MHz)2962.29722962.56 Δ J (kHz)1.38961.3896* Δ JK (kHz)-2.4936-0.895 Δ K (kHz)1.21691.27 δ J (kHz)-0.0103 δ K (kHz)-2.095 N lines 58410 * Δ J value fixed to those of previous work.

18. Conclusions:  Constructed a new, inexpensive room-temperature chirped-pulse Fourier transform microwave (RT- CP-FTMW) spectrometer.  Confirmed its frequency accuracy by performing tests on methanol.  Measured and fit the ground state and first excited vibrational state of pyridine in the 10-18 GHz region of the spectrum.

19. Future Work  Frequency doubler 0 - 500 MHz sweep (instead of 0-250 MHz)  More Construction…

20. Acknowledgements:  Dr. Steve Shipman (New College of Florida)  The Pate lab (University of Virginia)  SCICU (South Carolina Independent Colleges and Universities) Student/Faculty Research Program  Coker College