Fourier transform infrared measurements on the spectra of the products of the evaporation of silicon/carbon mixtures trapped in Ar at similar to 10 K, combined with the results of ab initio Calculations published earlier, and density functional theory (DFT) calculations carried out in the present work, have resulted in the detection for the first time of the linear SiC4Si cluster. Two vibrational fundamentals have been assigned, the C=C stretching mode nu(4)(sigma(u))= 1807.4 cm(-1), and the Si-C stretching mode nu(5)(sigma(u))=719.1 cm(-1). The observed frequencies, relative intensities, and isotopic shifts are in very good agreement with the results of the DFT calculations and confirm the previously predicted, linear symmetric geometry for the ground state of SiC4Si.