title: Nonstandard behavior of a negative ion reaction at very low temperatures.
abstract: We have studied the negative ion reaction NH2-+H_{2}-->NH_{3}+H- in the temperature range from 300 to 8 K. We observe a strongly suppressed probability for proton transfer at room temperature. With decreasing temperature, this probability increases, in accordance with a longer lifetime of an intermediate anion-neutral complex. At low temperatures, a maximum in the reaction rate coefficient is observed that suggests the presence of a very small barrier at long range or a quantum mechanical resonance feature.
authors.affiliation: Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Otto
authors.forename: J
authors.initials: J
authors.lastname: Mikosch
authors.forename: S
authors.initials: S
authors.lastname: Trippel
authors.forename: M
authors.initials: M
authors.lastname: Weidemüller
authors.forename: R
authors.initials: R
authors.lastname: Wester