  In order to facilitate IR absorption measurements of mass-selected ions
isolated in cryogenic matrices, we have upgraded an ion beam deposition
apparatus encompassing a Bruker IFS66v/S FTIR spectrometer. A synthetic diamond
beam splitter without compensator plate and UHV diamond viewports were
installed. We have also modified the IR detector chamber to allow measurements
with 5 different detectors. As a result we can now obtain FT absorption spectra
from 12000 cm$^{-1}$ to 15 cm$^{-1}$ with the same sample held under ultrahigh
vacuum conditions, simply by switching between appropriate IR detectors. We
demonstrate performance of the upgraded FTIR spectrometer by presenting
measurements of matrix isolated fullerene ions and an adhesive tape.
