Direct measurements of collisionally broadened Raman linewidths of CO2 S-branch transitions
Abstract
We report direct measurements of S-branch Raman-coherence lifetimes of CO2 resulting from CO2–CO2 and CO2–N2 collisions by employing time-resolved picosecond coherent anti-Stokes Raman scattering spectroscopy. The S-branch (ΔJ = +2) transitions of CO2 with rotational quantum number J = 0–52 were simultaneously excited using a broadband (∼5 nm) laser pulse with a full-width-at-half-maximum duration of ∼115 ps. The coherence lifetimes of CO2 for a pressure range of 0.05–1 atm were measured directly by probing the rotational coherence with a nearly transform-limited, 90-ps-long laser pulse. These directly measured Raman-coherence lifetimes, when converted to collisional linewidth broadening coefficients, differ from the previously reported broadening coefficients extracted from frequency-domain rotational Raman and infrared-absorption spectra and from theoretical calculations by 7%–25%.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 10, 2013
- Source ID
- 10.1063/1.4774093
Entities
People
- Hans U. Stauffer
- James. R. Gord
- Joseph R. Gord
- Naibo Jiang
- Paul S. Hsu
- Sukesh Roy
- Waruna D. Kulatilaka
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- Purdue University