Atomic vapor filter for two-dimensional Rayleigh imaging experiments with a narrow-band KrF excimer laser

An optical transition of atomic iron can be used to build a two-dimensional absorption filter that operates in the tuning range of a narrow-band KrF excimer laser (0.05-cm(-1) bandwidth). Iron atoms with a number density of 2 × 10(13) cm(-3) are produced by thermal dissociation of iron pentacarbonyl [Fe(CO)(5)]. With this filter it is possible to discriminate Mie and surface-scattered light against Rayleigh scattering. For Rayleigh scattering from the exhaust gas of a methane-air flame at a measured temperature of 1970 K, the ratio of transmission for Rayleigh scattering to transmission for Mie scattering is 16.8. Single-shot scattering from the exhaust gas of a high-pressure burner is presented as an application.