Partial transitions between initial and final states of definite relative angular momentum are studied for the nonmesonic weak decay of 12 Λ C . Compact expressions for the matrix elements in momentum space are given for nucleons in any orbital. It is shown that, in contrast to nuclear matter, the S→S and S→P transitions contribute significantly to the total rate. Implications are discussed for the ratio of the neutron- to proton-induced rates and of the parity-violating to parity-conserving transitions. Furthermore, transitions coming from initial relative ΛN P states are shown to be small.