A tetrahedral MCl4 type molecule in which M is isotopically pure and Cl is in natural abundance consists of five isotopic species due to the mixing of the 35Cl (75.4%) and 37Cl (24.6%) isotopes. Table I lists their symmetry, percent natural abundances, and symmetry species of infrared active modes corresponding to the v3 vibration of the Td molecule. The v3 bands of CCl4 and 28SiCl4 in argon matrices exhibit "five-peak chlorine isotope patterns" due to overlap of the nine bands listed in Table I. The vertical lines shown in Fig. 1A' indicate such a pattern for 74GeCl4.
David Tevault, J. David Brown, and Kazuo Nakamoto, "Matrix-Isolation Infrared and Computer-Simulation Spectra (v3 Bands) of GeCl4, GeBr4, and GeI4 in Argon Matrices," Appl. Spectrosc. 30, 461-462 (1976)