Two optical absorption bands are identified as arising from the negative charge state of each of the P-, As-, and Sb-vacancy pairs in silicon. The more prominent band for each is at 6150, 6000, and 5500 cm−1, respectively. A second broader partially overlapping band at ∼8500 cm−1is also present for each. Dichroism produced in the bands by uniaxial stress reveals a static Jahn-Teller distortion of opposite sign to that for the neutral state previously studied by EPR. The absorption bands can be identified as electron transitions from filled to empty orbitals of a simple one-electron molecular orbital model for the defect.