Experimental determination of Rayleigh scattering cross-sections at 408 nm

Cavity ring-down spectroscopy (CRDS) has been applied to retrieve accurate Rayleigh scattering cross-sections, _Rayl. for a set of atmospheric gases at 408 nm. Step pressure changes and pressure ramps were used in three different but similar optical cavities to measure light extinction by N 2 , O 2 , Ar, CO, CO 2 , N 2 O, CH 4 and synthetic air (SA). The experimentally determined _Rayl. were compared with _Rayl. values calculated for these atmospheric gases using knowledge of extrapolated literature values of the refractive index ( n ) and King correction factors measured in different spectral regions. The difference between measured and calculated _Rayl. using the most recently published dispersion relationship for N 2 O and CH 4 is 0.6