Exponential Approximation by Stein's Method and Spectral Graph Theory
  General Berry-Esseen bounds are developed for the exponential distribution using Stein's method. As an application, a sharp error term is obtained for Hora's result that the spectrum of the Bernoulli-Laplace Markov chain has an exponential limit. This is the first use of Stein's method to study the spectrum of a graph with a non-normal limit. 
Sourav Chatterjee, Jason Fulman, and Adrian Rollin