All-electronic THz-wave gas sensing via absorption spectroscopy
Authors
Rice, Timothy Emre
ORCID
https://orcid.org/0000-0002-6740-9404
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Other Contributors
Borca-Tasçiuc, Theodorian
Hella, Mona Mostafa
Narayanan, Shankar
Tekawade, Aniket
Oehlschlaeger, Matthew A.
Hella, Mona Mostafa
Narayanan, Shankar
Tekawade, Aniket
Oehlschlaeger, Matthew A.
Issue Date
2022-05
Keywords
Aeronautical engineering
Degree
PhD
Terms of Use
Attribution-NonCommercial-NoDerivs 3.0 United States
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute (RPI), Troy, NY. Copyright of original work retained by author.
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute (RPI), Troy, NY. Copyright of original work retained by author.
Full Citation
Abstract
Gas sensing via THz-wave absorption spectroscopy is developed for the detection of severalvolatile organic compounds, halogenated hydrocarbons, and nitrogen-containing compounds
using a broadband electronics-based THz wave spectrometer. Spectral absorption is
characterized in the frequency range from 220 to 330 GHz, a region where atmospheric
attenuation is minimal, scattering from particles and aerosols is negligible, spectral selectivity is
high for the chosen compounds, and microelectronic radiation sources and detectors are being
developed. The target compounds of the present study are important in industrial, chemical,
combustion, environmental, agricultural, and medical processes in which gas sensors are desired.
Experiments are conducted at room temperature and at pressures of 0.25−16 Torr, conditions
where pressure-broadening (collisional line-broadening) often results in complex blended
spectra. The observed transitions mostly exist for rotational absorption bands for ground
vibrational states but some transitions are also observed for low-lying vibrationally-excited
states. Where available, the measurements agree well with spectral simulations and documented
line positions; however, most of the present experiments are the first-of-their-kind and there are
not suitable experimental comparisons. Detection limits for remote gas sensing based on the
electronic spectrometer are estimated to be of the order 10^(12)-10^(13) molecules cm^(-3) per meter pathlength. For dilute gases in air at 1 atm, detection limits range from 5 to 1,000 ppm per meter
pathlength. The present study illustrates the potential for THz-wave quantitative gas sensing
using all-electronic miniaturized systems for the polar gases of industrial relevance. As humanity
becomes increasingly interested in the mitigation of anthropogenic greenhouse gases, local and
global air pollution, and industrial air safety, inexpensive remote gas sensors, such as the type
pursued in this thesis, should be in critical demand.
Description
May 2022
School of Engineering
School of Engineering
Department
Dept. of Mechanical, Aerospace, and Nuclear Engineering
Publisher
Rensselaer Polytechnic Institute, Troy, NY
Relationships
Rensselaer Theses and Dissertations Online Collection
Access
CC BY-NC-ND. Users may download and share copies with attribution in accordance with a Creative Commons
Attribution-Noncommercial-No Derivative Works 3.0 license. No commercial use or derivatives
are permitted without the explicit approval of the author.