Measurements of the weak UV absorptions of isoprene and acetone at 261-275 nm using cavity ringdown spectroscopy for evaluation of a potential portable ringdown breath analyzer

• Published in: Sensors (Basel, Switzerland) Vol. 13; no. 7; pp. 8170 - 8187
• Main Authors: Sahay, Peeyush, Scherrer, Susan T, Wang, Chuji
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26.06.2013; MDPI
• Subjects: acetone; Acetone - analysis; Biomarkers; Biosensing Techniques; breath biomarker; Breath tests; Breath Tests - instrumentation; Breath Tests - methods; Butadienes - analysis; Carbon dioxide; chemistry; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CRDS; Diodes; engineering; Equipment Design; Equipment Failure Analysis; Gases; Hemiterpenes - analysis; instruments & instrumentation; isoprene; Lasers; Mass spectrometry; Pentanes - analysis; Scientific imaging; Sensors; Spectrophotometry, Ultraviolet - instrumentation; Spectrophotometry, Ultraviolet - methods; UV absorption cross-sections; VOCs; Volatile organic compounds; United States > US; Mississippi
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s130708170

The weak absorption spectra of isoprene and acetone have been measured in the wavelength range of 261-275 nm using cavity ringdown spectroscopy. The measured absorption cross-sections of isoprene in the wavelength region of 261-266 nm range from 3.65 × 10⁻²¹ cm².molecule⁻¹ at 261 nm to 1.42 × 10⁻²¹ cm².molecule⁻¹ at 266 nm; these numbers are in good agreement with the values reported in the literature. In the longer wavelength range of 270-275 nm, however, where attractive applications using a single wavelength compact diode laser operating at 274 nm is located, isoprene has been reported in the literature to have no absorption (too weak to be detected). Small absorption cross-sections of isoprene in this longer wavelength region are measured using cavity ringdown spectroscopy for the first time in this work, i.e., 6.20 × 10⁻²³ cm².molecule⁻¹ at 275 nm. With the same experimental system, wavelength-dependent absorption cross-sections of acetone have also been measured. Theoretical detection limits of isoprene and comparisons of absorbance of isoprene, acetone, and healthy breath gas in this wavelength region are also discussed.