The emission spectrum of OH(A-X) is clearly observed in the photo-initiated reaction with the cluster beam of HBr . N2O for the first time. The rotational distribution of the product OH(A) is characterized as Boltzmann-type : with temperature of 3500+/-1000 K. The vibrational distribution is found to be 1:0.45+/-0.15:0.01+/-0.01 for nu = 0, 1, and 2, respectively. The product initial distribution observed in this work significantly differs from the one for its corresponding bimolecular reaction of H+N2O. The product OH(A) formed in the cluster reaction is more excited in rotation and less excited in vibration; inversely, vibration is more excited than rotation for the bimolecular reaction. This result suggests new pathways open due to geometrical constraints in the intra-cluster reaction.