In this paper we utilize the molecular dynamics spectral density method to explore the absorption line shapes of the ‘SO - 3P~(6s[3/2]1) electronic excitation of Xe in XeArN (N = 12-206) over the temperature range T = 10-40 K, with the Xe atom being located in distinct substitutional sites of the heterocluster (at T I 30 K), or in an interior position in nonrigid and in amorphous clusters. The Xe(’So-3Pl) extravalence excitations provide a sensitive microscopic probe for the local microenvironment of the Xe atom in these elemental clusters. The electronic excitations of Xe were described by the modified tight binding scheme (Webber, S.; Jortner, J.; Rice, S. A. J. Chem. Phys. 1965,42, 1907) with reliable Xe(3P~)-Ar(1So) excited-state exp-6 pair potentials (Messing, I.; Raz, B.; Jortner, J. J. Chem. Phys. 1977, 66, 2239). The site-specific and clustersize-dependent spectroscopic observables were characterized in terms of the blue spectral shift dv of the absorption band peak, the spectral line width (FWHM) r of the band, the spectral line shape, and their temperature dependence. The simulated spectra reveal an atomic shell structure with a hierarchy of Xe occupied site-specific spectral shifts decreasing in the order &(central site) > &(interior sites) > &(substitutional surface sites) > &(top atom), providing a spectroscopic method for the interrogation of the site-specific local structure. A quantification of the site specificity and the temperature dependence of BY was obtained in terms of its (nearly size invariant) exponential dependence on the average Xe- Ar nearest-neighbor distance, with the preexponential being proportional to the number of the nearest neighbors. We provided a spectroscopic identification of three temperature induced configurational changes in XeArN clusters, Le., a center surface dynamic isomerization of Xe in XeAr12 at T > 30 K, cluster configurational dilation around the central Xe atom in XeArN (N 2 54 with T 2 13 K for N = 54 and 35 K 130) clusters allowed for the identification of the Xe-occupied site-specific excitations of the central, interior and substitutional surface sites, while no evidence was obtained for the existence of the top atom site, which is precluded by surface melting. From the simulated temperature dependence of dv for the central site in large (N = 146-200) clusters, the cluster temperature was estimated to be T = 30-35 K. For XeArl2 we were able to identify the excitations of the center and surface sites at T = 30 K. Finally, the effects of nuclear dynamics on the spectra were inferred from the analysis of the power spectra of the energy gap correlation function, which established the dominance of the stochastic slow modulation limit for the line broadening.