Far infrared absorption in gaseous CCl4 and CS2

The absorption spectra of gaseous CS2, CCl4, and a gaseous mixture of CCl4 and argon at temperatures up to 400 K in the frequency region below 140 cm−1 are reported. From the results on CCl4, the octupole moment is estimated to be 16 ± 3.0 × 10−34 esu; the hexadecapole moment, 64 ± 12 × 10−42 esu. For CS2, if a previously measured value of 3.6 B for the quadrupole moment is assumed, the hexadecapole moment is estimated to be less that 24 × 10−42 esu, considerably less than an earlier theoretical estimate.