RE 12 CHIRPEDPULSE FOURIER TRANSFORM MICROWAVE SPECTROSCOPY OF

RE 12 CHIRPED-PULSE FOURIER TRANSFORM MICROWAVE SPECTROSCOPY OF 2 -CHLORO-3 -FLUOROPYRIDINE AND 2 -CHLORO-6 -FLUOROPYRIDINE Sean Arnold, J. Chase Chewning & Gordon Brown Department of Science and Mathematics, Coker College, Hartsville, SC, 29550 USA

Purpose: • Measure and assign the rotational spectra of 2 -Cl-3 -F-Pyridine and 2 -Cl-6 -F-Pyridine • Instrumentation test: Is our chirped-pulse spectrometer capable of dealing with two nuclear quadrupoles? 2 -chloro-3 fluoropyridine 2 -chloro-6 fluoropyridine 2

Spectrometer Diagram 240 MHz 3

250 MHz Chirped Pulse: 4

Chirped-Pulse Microwave Spectrometer 5

CP-FTMW Resolution Low-Res Hi-Res 20 μs FID Peak Width ~130 k. Hz (FWHM) 100 μs FID Peak Width ~ 24 k. Hz (FWHM) Doppler Splitting ~ 70. k. Hz

Experimental: 2 -Cl-3 -F-Pyridine Frequency (MHz) 10, 000 signal averages (approximately 40 hours of measurement time) 100 μs FID 50 psi backing pressure (He/Ne mix) Sample evaporated at room temperature

Experimental 2 -Cl-6 -F-Pyridine Frequency (MHz) 10, 000 signal averages (approximately 40 hours of measurement time) 100 μs FID 50 psi backing pressure (He/Ne mix) Sample heated in nozzle to ~80° C 8

2 -Cl-3 -F-Pyridine Assignments

2 -Cl-3 -F-Pyridine Assignments 10

2 -Cl-6 -F-Pyridine Assignments 11

Rotational Parameters for 2 -chloro-3 -fluoropyridine Rotational Parameters 2 -chloro-3 -fluoropyridine (35 Cl) 2 -chloro-3 -fluoropyridine (37 Cl) B 3 LYP/ 6‑ 311++g(d, p) Experimental A (MHz) 2936. 0358 2949. 4216 (38) 2920. 3469 2940. 894 (13) B (MHz) 1595. 7478 1612. 22964 (87) 1563. 4143 1570. 9766 (12) C (MHz) 1033. 8474 1042. 2833 (11) 1018. 2773 1023. 8501 (17) DJ (k. Hz) 0. 049 0. 035 (13) 0. 048 0. 038 (16) 3/2 Χaa N(MHz) 0. 745 0. 554 (66) 0. 62474 0. 45 (12) ¼ Χbb – Χcc N(MHz) -1. 680 -1. 631 (19) -1. 6595 -1. 621 (41) 3/2 Χaa Cl(MHz) -102. 333 -107. 400 (58) -81. 022 -84. 98 (21) 2. 805 2. 276 (18) 2. 2729 1. 924 (78) N/A 317 N/A 155 OMC (MHz) N/A 0. 0090 N/A 0. 0235 Δ (amu*A 2) -0. 0000025 0. 062 -0. 000016 -1. 11 ¼ Χbb – Χcc Cl(MHz) Number of Assigned Lines

Rotational Parameters for 2 -chloro-6 -fluoropyridine Rotational Parameters 2 -chloro-6 -fluoropyridine (35 Cl) 2 -chloro-6 -fluoropyridine (37 Cl) A (MHz) B 3 LYP/ 6‑ 311++g(d, p) 3412. 8187 3420. 8161 (15) B 3 LYP/ 6‑ 311++g(d, p) 3403. 8890 B (MHz) 1245. 8076 1258. 4740 (17) 1211. 4569 1223. 9568 (17) C (MHz) 912. 6544 919. 9140 (13) 893. 46823 900. 71002 (61) DJ (k. Hz) 0. 0371 0. 027 (19) - - 3/2 Χaa N (MHz) 2. 73374 2. 166 (99) 2. 70 2. 51 (13) ¼ (Χbb – Χcc) N (MHz) -1. 70307 -1. 608 (17) -1. 697 -1. 590 (21) Χab N (MHz) -1. 56 -1. 45 (85) - - 3/2 Χaa Cl(MHz) -86. 401 -89. 90 (12) -68. 724201 -71. 33 (18) ¼ Χbb – Χcc Cl(MHz) -0. 13151 -0. 560 (19) -0. 00125 -0. 327 (26) Χab Cl (MHz) -33. 48 -34. 23 (49) -25. 8 -26. 8 (20) Number of Assigned Lines N/A 153 N/A 111 OMC (MHz) N/A 0. 00814 N/A 0. 0217 Δ (amu*A 2) -0. 000041 0. 0592 -0. 000016 0. 0607 Experimental 3411. 8877 (21)

Conclusions: Measured 8 -18. 5 GHz spectra of the two molecules Determined experimental rotational and quadrupole coupling constants Successfully measured analyzed compounds with two nuclear quadrupoles 2 -chloro-3 fluoropyridine 2 -chloro-6 fluoropyridine

Acknowledgements National Science Foundation (CHE-1213560) American Chemical Society-Petroleum Research Fund (PRF #50746 -UN 16) South Carolina EPSCo. R/IDe. A GEAR: RE Program Coker College Sean Arnold Chase Chewning