The IR spectrum of Si2H7+ provides the first spectroscopic characterization of the geometric and electronic structure of this polysilane cation. In their Communication on page 1568 ff., O. Dopfer et al. give direct evidence for a nonlinear SiHSi proton bridge with a three-center two-electron bond. The IR fingerprint may be used for its identification in silane plasmas, including the interstellar medium (copyright ESO/F. Meynadier, M. Heydari-Malayerie, N. R. Walborn).