Journal of Statistical Physics, Vol. 32, No. 1, 1983. p. 81-94.
The behavior of an impurity spin in a one-dimensional chain is investigated using the Glauber model. Two different types of impurities are considered and exact expressions for the average spin of the impurity, given that the impurity was initially excited out of equilibrium, are found. The behavior of these models is discussed in detail and their relevance to other physical situations is considered.