A one-electron pseudopotential hole-particle formalism is implemented to investigate excitations in xenon molecules and clusters. Within this framework, averaged relativistic electron-Xe and electron-Xe+ pseudopotentials are determined to incorporate the excited particle contributions. A consistent hybrid scheme for spin-orbit coupling is developed, involving an atoms-in-molecules type approximation for the hole and a pseudopotential operator for the particle. The reliability of the one-electron pseudopotential scheme is first checked on the atomic spectrum of xenon and the transferability to high excited states is demonstrated. The molecular behavior of the formalism is also investigated by determining the potential energy curves of the lowest excimer states of Xe-2(*). The spectroscopic constants (D-e, omega(e), and omega(exe), respectively) are found to be 4173, 108, and 1.17 cm(-1) for state (1)0(u)(-)(6s P-3(2)), 4197, 109, and 1.11 cm(-1) for state (1)1(u)(6s P-3(2)), and 4250, 107, and 1.14 cm(-1) for state (1)0(u)(+)(6s P-3(2)).