THE O/OH/H2O TRANSITION IN PARTIALLY IONIZED GLOBULES IN IC1396

we propose to observe the farinfrared lines of o, oh and h2o in photondominated regions (pdrs) associated with partially ionized globules (pigs) in the hii region ic1396. the distances of the various globules to the illuminating o6 star hd206267 vary by more than a factor of 4. since the incident radiation field controls the formation and destruction of atomic and molecular species, the abundances of o, oh and h2o are expected to vary greatly from globule to globule and will provide stringent tests of the o/oh/h2o transition in pdr models. these farinfrared lines cannot be observed from the ground. the oh and h2o lines are expected to be weak, hence the high sensitivity of iso is essential for this study. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]