@article{MentenGuestenLeurinietal.2008,
  author    = {K. M. Menten and R. G{\"u}sten and S. Leurini and S. Thorwirth and C. Henkel and B. Klein and C. L. Carilli and M. J. Reid},
  title     = {Submillimeter water and ammonia absorption by the peculiar z ? 0.89 interstellar medium in the gravitational lens of the PKS 1830-211 system},
  series   = {A\&A (Astronomy \& Astrophysics)},
  volume    = {492},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361:200810041},
  pages     = {725 -- 730},
  year      = {2008},
  abstract  = {Using the Atacama Pathfinder Experiment (APEX) telescope, we have detected the rotational ground-state transitions of ortho-ammonia and ortho-water toward the redshift 0.89 absorbing galaxy in the PKS 1830-211 gravitational lens system. We discuss our observations in the context of recent space-borne data obtained for these lines with the SWAS and Odin satellites toward Galactic sources. We find commonalities, but also significant differences between the interstellar media in a galaxy at intermediate redshift and in the Milky Way. Future high-quality observations of the ground-state ammonia transition in PKS 1830-211, together with inversion line data, will lead to strong constraints on the variation in the proton to electron mass ratio over the past 7.2 Gyr.},
  language  = {en}
}