The absorption spectra of light ions in the vacuum ultraviolet have been recorded using two lasers producing plasmas, one acting as the background continuum radiation source and the other as the absorbing medium. The photoionization cross section of Be+ at 18.2eV has been measured. The result is in good agreement with theoretical predictions. The absorption spectrum of B+ corresponding to transitions of the type 2s2p 3P0-2snd 3D and 2s2 1S-2snp 1P0 have been observed too.