Abstract
We have recorded the gas phase spectrum of isoprene at room temperature from the mid-infrared range and into the visible range (600 cm−1 to 17050 cm−1). Absorption spectra were obtained by Fourier transform infrared, conventional dispersion ultraviolet–visible-near-infrared and cavity ring-down spectroscopy to cover the entire range with a resolution comparable to that of the instruments on the James Webb Space Telescope. We have assigned the CH-stretching fundamental and overtone bands corresponding to the ΔvCH=1−6 transitions based on anharmonic vibrational calculations using normal mode and local mode models, for the lower- and higher-energy regions, respectively. We have determined accurate absolute intensities of the observed CH-stretching regions and compare with existing experimental values and with theoretical results. The accuracy of our absolute band intensity is about 2% in the fundamental region and about 10% in the 6 orders of magnitude weaker highest overtone region. Our spectrum can facilitate the detection and possibly quantification of isoprene in planetary atmospheres.
Original language | English |
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Article number | 125667 |
Journal | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy |
Volume | 330 |
Number of pages | 10 |
ISSN | 1386-1425 |
DOIs | |
Publication status | Published - 2025 |
Bibliographical note
Publisher Copyright:© 2025 The Authors
Keywords
- Bio-signature
- Cavity ringdown spectroscopy
- Fundamental and overtone transitions
- JWST
- Local mode models
- Vibrational band intensities