S3 and S4 absorption cross sections in the range of 340 to 600 nm and evaluation of the S3 abundance in the lower atmosphere of Venus

S₃ absorption cross section equals 6×10^?17 cm² at 400 nm, 6 × 10^?19 cm² at 500 nm (less by a factor of 4 than that given by Sanko), 4×10^?20 cm² at 600 nm. That of S₄ equals 1.5 × 10^?17 cm² at 450 nm, 8 × 10^?17 cm² at 500 nm, and 4.7 × 10^?17 cm² at 600 nm. Preliminary evaluation of the S₃ mixing ratio in the lower atmosphere of Venus is (8±3)×10^?11 at 5 to 25km according to the Venera 14 measurements and several times lower at the locations of the Veneras-11 and -13.