TB06 TB06 PRECISION FREQUENCY MEASUREMENT OF N 2 O TRANSITIONS NEAR 4.5  m AND ABOVE 150  m WEI-JO TING, CHUN-HUNG CHANG, SHIH-EN CHEN, HSUAN CHEN CHEN, JOW- TSONG SHY, BRIAN DROUIN, ADAM DALY Jet Propulsion Laboratory, California Institute of Technology, Department of Physics, National Tsing Hua University, Institute of Photonics Technologies, Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University 6/17/2014TB061

Background and Motivation 66 th molecular spectroscopy symposium – TA10 - HIGH PRECISION MID-IR SPECTROSCOPY OF N 2 O NEAR 4.5 μm Similar to CO 2, N 2 O is one of the important greenhouse gases. No extensive heterodyne frequency measurements of the line center. New and refined molecular constants are of great importance to atmospheric chemistry, meteorology, and astrophysics. Drouin, B. J., F.W. Maiwald, "Extended THz measurements of nitrous oxide, N 2 O," Journal of Molecular Spectroscopy, 236 (2): , th molecular spectroscopy symposium – WI08 - Applications of Molecular Spectroscopy Using Cascaded Frequency Multiplication Work was directed at characterizing multipliers, not necessarily precision measurements 6/17/2014TB062

Partial energy diagram of N 2 O cm cm cm cm cm cm cm cm -1 Green : Laser transitions that have been measured by Whitford et al.(1975) Blue : Suggested by Dr. A. G. Maki. Red: Can be derived from Blue and Green transitions. 6/17/2014TB063

mW PPLN Difference Frequency Generation Source Experimental Set-up Third derivative signal of the R(10) saturation dip. Here, the scan rate is 2.0 MHz/s and lock-in time constant is 30 ms. 44 transitions J = 1 – 100 P- and R- branches 6/17/2014TB064

New and refined molecular constants are of great importance to atmospheric chemistry, meteorology, and astrophysics , cm cm cm cm cm cm cm cm -1 Combined Precision Datasets require sophisticated analysis 6/17/2014TB065

SPFIT can do it N2O gs and vibs only Thu Feb 20 09:00: E E E 's' /GS / / / / / E E E E E E E E E E E E E E E E E E E E E E E E E E-037 … E E E E E E E E E E E E E E E E-030 /WF 6/17/2014TB066

Precision IR vs. THz Addition of IR saturation spectra to analyses revealed errors in ground state measurements of Drouin & Maiwald 2005 Improvements to THz coverage and gas cells suggested we try harder TransitionObserved frequency (MHz) a f obs -f cal ( ｋ Hz) f obs -f HITRAN (MHz) P(90) (75) P(85) (50) P(80) (25) P(75) (25) …. 6/17/2014TB067

The Frequency Multiplication Submillimeter Spectrometer AMC-10 Anritsu SR830 HP FG AM/FM/TM sync diode or Si gas pre-amp vacuum pump sample sweep synthesizer mm-wave module MMIC amps submm multipliers waveguide feedhorns sample cell detector waveform generator lock-in-amplifier PC GPIB modulation AMC - 12AMC-10D170D190D210X3 WR1.9x5D210X3X2X GHz cm -1 WR1.2x5X2X2X2X3X3X2X2X3X3X3X2D170 X9D190 X9D210 X9X3X3X GHz cm -1 HPWR3.4 ZBDWR1.9 ZBDWR0.8 ZBDQODInSbSiPM < – GHz < cm -1 6/17/2014TB068

Lamb Dips with THz sources Pearson J., B. Drouin, A. Maestrini, I. Mehdi, J. Ward, R. Lin, S. Yu, J. Gill, B. Thomas, C. Lee, G. Chattopadhyay, E. Schlecht, F. Maiwald, P. Goldsmith, P. Siegel "Demonstration of a room temperature THz coherent spectroscopy source", Review of Scientific Instruments 82(9), , Routine for strong lines < 1 THz, Schottky detectors below 0.7 THz, Si bolometers above 0.7 THz. Lamb-Dip ‘machine’ built by T. Crawford 6/17/2014TB069

New THz Measurements 175 new pure rotational transitions 33 sub-Doppler Second harmonic detection of saturated absorption dip for the J = 12 – 11 rotational transition in the state. The pressure was 0.1 Pa, the modulation depth was 18 kHz, resulting in a linewidth of 22 kHz and a frequency measurement uncertainty of 1 kHz. J’l’v’JlvFrequency (MHz) Uncertaint y (MHz) … 6/17/2014TB0610

New & Improved Model ±2 0 b EnEn (32) (33) (37) (73) (63) BnBn (127) (156) (167) (97) a (97) a (35) D n / kHz (163) (188) (248) (260) (33) (103) H n / mHz ( 83) (91) (140) (165) -8.37(287) (55) L n / nHz-9.25(155)-9.57(162)-15.24(199)-13.4(75) M v / pHz0.290(95)fffff q n / MHz (147) (42) (265) (40) q nJ / kHz (144) q nJJ / mHz (242) W F / GHz 1109 b (119) W FJ / kHz Datasetavg. (MHz)s.d. (MHz) σ red N This Work-THz This work-IR Burrus & Gordy [5] Pearson et al. [6] Lafferty & Ride [7] Andreev et al. [8] Morino et al. [9] Drouin &Maiwald [10] Morino et al. [11] Lemaire et al. [12] Tachikawa et al. [15] Hornemann [16] Stateavg. (MHz)s.d. (MHz) σ red N g.s ± ± /17/2014TB0611

Acknowledgements National Science Council, Taiwan Ministry of Education, Taiwan NASA ACLAB JPL SWAT JPL TEFIM 6/17/2014TB0612 © 2014 California Institute of Technology. Government sponsorship acknowledged.