title: Direct measurements of collisionally broadened Raman linewidths of CO2 S-branch transitions.
abstract: We report direct measurements of S-branch Raman-coherence lifetimes of CO(2) resulting from CO(2)-CO(2) and CO(2)-N(2) collisions by employing time-resolved picosecond coherent anti-Stokes Raman scattering spectroscopy. The S-branch (ΔJ = +2) transitions of CO(2) 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 CO(2) 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%.
authors: Spectral Energies, LLC, 5100 Springfield Street, Suite 301, Dayton, Ohio 45431, USA. sroy@woh.rr.com
authors: Sukesh
authors: S
authors: Roy
authors: Paul S
authors: PS
authors: Hsu
authors: Naibo
authors: N
authors: Jiang
authors: Joseph R
authors: JR
authors: Gord
authors: Waruna D
authors: WD
authors: Kulatilaka
authors: Hans U
authors: HU
authors: Stauffer
authors: James R
authors: JR
authors: Gord