Irradiation of carbon disulfide vapor at 313 nm produces a solid aerosol of nanosized particles, which slowly aggregate and settle. Elemental analysis shows the composition of the solid is CS (1.98), and the density is 1.92 +/- 0.03 g/cm(3). Physical properties of this material were found to be nearly identical to Bridgman’s black carbon disulfide, which is prepared from liquid CS2 at pressures above 40 kbar and temperatures around 150 degrees C. The IR spectrum of (CS2)(x) includes features at 1410 (s, br), 1298 (ms), 1250 (m), 1067 (vs), 891(w), 854 (vw), 821(w), 550 (w), 507 (w), 471 (m), and 447 cm(-1) (m). The (CS2)(x) polymer undergoes photooxidation (lambda less than or equal to 500 nm) in the presence of molecular oxygen to produce CO, OCS, SO2, CS2, sulfur, and a partially oxidized polymer. The relative amounts of these products vary widely with the specific experimental conditions employed. Vibrational spectroscopic studies of ((CS2)-C-13)(x), and the material prepared by irradiating a 50/50 mixture of (CS2)-C-13/(CS2)-C-12, suggest that it predominantly consists of highly S-S cross-linked chains of (CS2)(x). This provides a convenient low-pressure route to an unusual phase of CS2 and helps elucidate the primary process in the photolysis of CS2 vapor.