title: Differential scattering cross-sections for CN A2Pi+Ar.
abstract: We present the first results from a novel experimental approach to the measurement of state-to-state differential scattering cross-sections for inelastic scattering of electronically excited CN A(2)Pi with Ar. Photodissociation of ICN with linearly polarized 266 nm radiation generates CN X(2)Sigma(+) (upsilon(")=0,J(")) with a near mono-energetic speed distribution and large anisotropy. Saturated optical pumping of the nascent CN X(2)Sigma(+) transfers this speed distribution without distortion to selected rotational quantum states of the A(2)Pi (upsilon(')=4) level. The products of rotational energy transfer within the A(2)Pi (upsilon(')=4) level into the J(')=0.5, F(2), f, state are probed using frequency modulated stimulated emission spectroscopy on the A-X (4,2) band with a single frequency external cavity tunable diode laser. Doppler profiles of transitions from individual rotational, spin-orbit and lambda doublet specific levels are acquired for different geometrical arrangements of photolysis polarization and probe propagation directions. The resulting Doppler profiles, which for this J(')=0.5 state cannot display a rotational angular momentum alignment, are combined to yield composite Doppler profiles depending on speed and translational anisotropy, which are analyzed to determine fully state-to-state resolved differential scattering cross-sections.
authors.affiliation: School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: Azhagammai
authors.initials: A
authors.lastname: Alagappan
authors.forename: Iain
authors.initials: I
authors.lastname: Ballingall
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Costen
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: McKendrick