In this article we explore the structural, dynamic, and spectroscopic implications of large local configurational changes in electronically excited Xe*Ar-N (N=12,54,146,199) heteroclusters, where the Xe*[=Xe(P-3(1))] atom is excited to the lowest dipole-allowed extravalence Rydberg excitation. The ultrafast femtosecond and picosecond dynamics driven by the short-range repulsive interaction between the vertically excited Xe* Rydberg and the cluster Ar atoms was studied by molecular dynamics simulations. From the analysis of the time dependence of the structural parameters for site-specific Xe excitations in medium-sized (N=54) and large (N=146,199) clusters, two general configurational relaxation phenomena were established: a ''bubble'' formation (i.e., a large configurational dilation around Xe*) for Xe Interior sites and a ''spring'' formation (i.e., the stretching of Xe* outside the duster) for Xe surface sites. General Xe site-specific features of both bubble and spring formation involve ultrashort (Gaussian) energy transfer to the cluster (similar to 50-100 fs characteristic times tau(ET)) inducing configurational relaxation, which manifests a multimodal time solution. The initial (Gaussian) temporal mode (similar to 150-300 fs characteristic times tau(0)>tau(ET)) is followed by an exponential mode (ps lifetime tau(1)), with subsequent impact induced, damped vibrational coherence effects with frequencies (omega(2),omega(3)). and exponential decay (ps lifetimes tau(2), tau(3)). The bubble formation for the central site of Xe*Ar-146 or Xe*Ar-54 is induced by energy transfer of tau(ET)congruent to 60 fs followed by subsequent multimodal dilation with tau(0) congruent to 170 fs and tau(1) congruent to 2 ps, and a subsequent expansion with coherent motion of vibrational ware packets with omega(2), omega(3) congruent to 20, 40 cm(-1) and tau(2), tau(3) congruent to 6 ps. The bubble reaches an equilibrium configuration after similar to 10 ps with asymptotic spatial expansion of Delta R-b* = 0.7-0.8 Angstrom. The spring formation for an exterior surface site of Xe*Ar-146 is tau(ET)congruent to 80 fs and tau(0) congruent to 210 fs, which is followed by a substantial (congruent to 1.2 Angstrom) Xe* stretching and a subsequent contraction accompanied by vibrational coherence effects with omega(2) congruent to 10 cm(-1) and tau(2) congruent to 20 ps, with the asymptotic spring spatial extension Delta R-s*congruent to 0.6 Angstrom, being accomplished after similar to 30 ps. Regarding dynamic cluster size effects we established that following vertical excitation at initial temperatures T-i = 10-30 K, the following phenomena are manifested: (i) Large Xe*Ar-146 and Xe*Ar-199 clusters exhibit short-time (10-20 ps) configurational relaxation in rigid clusters, (ii) The central site in a medium-sized Xe*Ar-54 cluster undergoes a rigid-nonrigid (''melting'') transition induced by the electronic excitation, with the Xe* manifesting lung-time (100-200 ps) mass transport from the interior bubble to the surface spring. (iii) Small Xe*Ar-12 clusters exhibit stepwise reactive dissociation on the ps time scale. The spectroscopic implications of large configurational relaxation in Xe*Ar-N (N = 54,146) clusters were interrogated hy the simulations of the Xe site-specific time-dependent spectral shifts in emission, which decrease from the initial large values [e.g. , delta nu(e)(t = 0) = 0.92 eV at T-i = 10 K for the central site] to low values. The time evolution of the emission spectral shifts is qualitatively similar to the structural dynamics, which involves initial ultrafast (similar to 50-100 fs) decay, a (ps) exponential contribution, and a damped oscillatory behavior. The time-resolved Xe site-specific emission spectral shifts obey an exponential structure-spectral relationship which is isomorphous with time-independent relations for the absorption spectral shifts and for the emission asymptotic spectral shifts. Finally, predictions are provided for the spectroscopic interrogation (by energy-resolved fluorescence) of the longer time (similar to 150 ps) Xe* bubble mass transport in nonrigid Xe*Ar-54 clusters. The long-time fluorescence spectra, which were simulated by the spectral density method, exhibit: (i) A Gaussian line shape, corresponding to the slow modulation limit. (ii) Spectral shifts ([delta nu(e)] = 0.01-0.1 eV) exhibiting a site-specific hierarchy, i.e., [delta nu(e)](central)>[delta nu(e)](interior)>[delta nu(e)]x(surface)>[delta nu(e)](top). (iii) Linewidths (full width at half-maximum) which follow the order of the site-specific hierarchy of the spectral shifts, The calculated site-specific emission spectral shifts and linewidths and the calculated Slakes shifts for central and interior bubble sites and for surface spring sites in Xe*Ar-146 are in reasonable agreement with the experimental results for Xe*Ar-1400 clusters. Out overall picture regarding the dynamic and spectroscopic implications of large excited-state configurational relaxation provides guidance, predictions, and insight for the fate of Rydberg states in clusters and in the condensed phase. (C) 1997 American Institute of Physics.