Broadband absorption and emission millimeter-wave spectroscopy between 220 and 325 GHz

Michael Szymkiewicz; Axel Hülsmann; Axel Tessmann; Michael Schlechtweg; Arnulf Leuther; Oliver Ambacher; Stefan Koch; Matthias Riedel; Ingmar Kallfass

doi:10.1117/12.2015222

29 May 2013 Broadband absorption and emission millimeter-wave spectroscopy between 220 and 325 GHz

Michael Szymkiewicz, Axel Hülsmann, Axel Tessmann, Michael Schlechtweg, Arnulf Leuther, Oliver Ambacher, Stefan Koch, Matthias Riedel, Ingmar Kallfass

Author Affiliations +

Proceedings Volume 8726, Next-Generation Spectroscopic Technologies VI; 872610 (2013) https://doi.org/10.1117/12.2015222
Event: SPIE Defense, Security, and Sensing, 2013, Baltimore, Maryland, United States

Abstract

A millimeter-wave spectroscope for the detection of triatomic gases has been constructed and characterized for frequencies between 230 and 325 GHz (H-band). The achieved results demonstrate a high sensitivity and low threshold detection. A circular lensed horn antenna transmits millimeter- waves into a gas-filled vacuum tube and excites triatomic gas molecules to a higher energy level, if the rotational resonance frequency of the molecule matches with the excitation frequency. At the other end of the tube a second lensed horn antenna receives the propagated electromagnetic wave and the millimeter-wave power is measured by a heterodyne receiver. By sweeping the radiated transmit frequency, the molecules' specific absorption can be detected. The measured absorption results are superimposed by standing wave effects within the tube. To eliminate the standing wave effects, spectroscopy on the basis of rotational spontaneous millimeter-wave emission was examined. This kind of spectroscopy decouples the transmitted from the received signal, whereby independent excitation and detection of the molecules are realized. The use of additional absorbers at the end of the gas tube decreases the decay time of the radiated wave inside the gas cell. In this paper, the detection of spontaneous emission of triatomic gas molecules with the use of a pulse-controlled transmitter and receiver is shown. Optimizations improved the stability and reproducibility of the measurements, and the detection threshold of nitrous oxide could be decreased to a ratio of 1/400. Furthermore, the implementation of a differential measurement method reduces the measurement time by a factor of 150 and simultaneously decouples of environmental influences.

Citation Download Citation

Michael Szymkiewicz, Axel Hülsmann, Axel Tessmann, Michael Schlechtweg, Arnulf Leuther, Oliver Ambacher, Stefan Koch, Matthias Riedel, and Ingmar Kallfass "Broadband absorption and emission millimeter-wave spectroscopy between 220 and 325 GHz", Proc. SPIE 8726, Next-Generation Spectroscopic Technologies VI, 872610 (29 May 2013); https://doi.org/10.1117/12.2015222

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
7 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Absorption

Molecules

Spectroscopy

Receivers

Gases

Transmitters

Antennas

Show All Keywords

Keywords/Phrases

Search In:

Publication Years