Ultra-violet absorption band-systems of PbO, PbS, PbSe and PbTe

A study has been made of the absorption spectra of PbO, PbS, PbSe and PbTe in the ultra-violet region (λ>2050 A.). The vibrational analysis of new bandsystems of PbS, PbSe and PbTe are reported, together with some observations on systems of PbO ( v e similar 35000) and of PbSe ( v e similar 24818 cm. -1 ) already known. The table below includes the values of v e , w e and x e w e at present available for the upper states of these molecules which are involved in absorption systems in this region of the spectrum.