Observation of IR Absorption Spectra of the Unstable PbH 4 Molecule

The IR absorption spectra of the unstable PbH 4 molecule are studied. The possibility of preparation of PbH 4 at sufficiently high concentrations (~10 mg/l) in a gaseous phase is demonstrated. The ν 3 band of PbH 4 is detected in a gaseous phase by the technique of infrared Fourier spectroscopy. The spectra of PbH 4 are mea- sured in a low-temperature argon matrix. The basic spectroscopic constants are obtained for the ν 3 = 1-0 tran- sition, and the position of the ν 4 band is determined. The results obtained confirm the tetrahedral symmetry of the PbH 4 molecule.