AMANDA L. STEBER, MARIYAM FATIMA, CRISTÓBAL PÉREZ, and MELANIE SCHNELL AN 18-26 GHz SEGMENTED CHIRPED PULSE FOURIER TRANSFORM MICROWAVE SPECTROMETER FOR ASTROCHEMICAL APPLICATIONS AMANDA L. STEBER, MARIYAM FATIMA, CRISTÓBAL PÉREZ, and MELANIE SCHNELL Styling: MPSD color: 44-89-160

Introduction Chirped pulse Fourier transform microwave spectroscopy Increased data throughput Used in both a large and small bandwidth configuration Segmented Chirped pulse Introduced in 2013 Used at mmw frequencies Utilizes lower cost components Introduces real time averaging Goals: Decrease the cost Decrease acquisition times G.G. Brown et al., J. Mol. Spectro, 238, 200 (2006) J.L. Neill et al., Opt. Express, 21, 19743 (2013)

Instrumentation N.A. Seifert et al., J. Mol. Spectro., 312, 13 (2015)

Instrumentation

Segmented, Fast Frame Chirped Pulse Divide 8 GHz bandwidth into 10 – 800 MHz segments Pulse train Depending upon the pumping speed you can fit multiple segments into one gas pulse

Phase Stability We are able to collect the pulses (that have been heavily attenuated by the switch)

Phase stability

OCS / Sensitivity 0.2 % OCS in Neon 3 bar backing pressure 200,000 averages 18O13CS SNR ~3:1 0.0021 % Not intensity calibrated

1-Hexanal 0.2% 1-Hexanal in Neon 1 bar backing pressure 1 nozzle

1-Hexanal N.A. Seifert et al., J. Mol. Spectro., 312, 13 (2015)

Spurious Signals Generated from the local oscillator Occur ~200 MHz 2M average spectrum

1-Hexanal Spurious SIgnals N.A. Seifert et al., J. Mol. Spectro., 312, 13 (2015)

Comparison between two approaches Broadband Segmented Effective Rep Rate 30 Hz 15 Hz Power/GHz 5 W/GHz 5-7 W/GHz Bandwidth 8 GHz /segment 800 MHz/segment Nozzles 3 1 Pulse Duration 1 ms 2 ms FID duration 10 ms LNA 48 dBm 45 dBm ~ Cost ~350,000 € ~150,000 € SNR of conformer 1 of 1-Hexanal 3500:1 ~1300:1

Astrochemistry Applications Broadband reaction screening Based on the work done at Uva Discharge nozzle Paired with the W-band instrument Astrochemically relevant molecules Alaninol Isoleucinol M.C. McCarthy et al., Astrophys. J. Suppl. Ser., 129, 129 (2000) D.P. Zaleski et al., Astrophys. J. Lett., 765, L10 (2013) R. A. Loomis et al., Astrophys. J. Lett., 765, L9 (2013)

Conclusions and Future Directions A new segmented, fast frame chirped pulse spectrometer has been built Potential to reduce time Reduces cost Future Directions Intensity calibration needs to be improved Spurious signals better cateloged Pumping speed improved

Acknowledgement ERC 638027 Louise Johnson Fellowship

Power Curve Power loss across electronics Frequency Dependent

1-Hexanal N.A. Seifert et al., J. Mol. Spectro., 312, 13 (2015)