{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T23:41:50Z","timestamp":1790725310986,"version":"4.1.0"},"reference-count":55,"publisher":"AIP Publishing","issue":"2","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,2,1]]},"abstract":"<jats:p>A new L-shaped molecular beam Fourier transform microwave spectrometer (L-FTMW) has been developed at Tennessee Tech University to perform both cavity and chirped-pulse rotational spectroscopy within a single platform. The instrument features an L-shaped high-vacuum chamber comprised of stainless-steel and polycarbonate sections, allowing orthogonal operation of Fabry\u2013Perot cavity and chirped-pulse configurations without mechanical reconfiguration. This paper focuses on the design, operation, and performance of the 8\u201318\u00a0GHz Fabry\u2013Perot cavity subsystem within the L-FTMW spectrometer. The cavity is formed by two 7.5-inch-diameter aluminum mirrors with 30\u00a0cm radii of curvature, arranged near-confocally and coupled to a near-coaxial pulsed molecular beam. A custom Python-based interface enables automated high-resolution mapping of cavity resonances and broadband data acquisition with minimal user intervention. The system routinely achieves 2\u00a0kHz frequency resolution, enabling precise measurement of hyperfine spectral features. Performance was validated through measurements of benchmark systems, including OCS isotopologues and their weakly bound van der Waals complexes. The 17O13CS isotopologue (natural abundance = 0.000\u2009397\u20092%, corresponding to \u223c40 ppb in a 1% OCS\/argon mixture) was detected within 5\u00a0min\u00a0of signal averaging at natural abundance with argon as the carrier gas. The simple mechanical design and open-source control software make the L-FTMW spectrometer a versatile and accessible platform for high-resolution rotational spectroscopy and future investigations of reaction dynamics and kinetics.<\/jats:p>","DOI":"10.1063\/5.0311736","type":"journal-article","created":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T13:44:51Z","timestamp":1770212691000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":1,"title":["Design and performance of an L-shaped Fourier transform microwave spectrometer (L-FTMW): Fabry\u2013Perot cavity spectrometer setup"],"prefix":"10.1063","volume":"97","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-7649-6481","authenticated-orcid":false,"given":"Rusiru P. 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