Condensation effects in K-shell excitation spectra of neon films

Using synchrotron radiation under high-resolution conditions, we have investigated the excitation of electronic states at the K edge in neon multilayers. In addition to the electron yield, we use photon-stimulated desorption of Ne+, Ne2+, and Ne-2(+) as near-edge x-ray-absorption fine-structure probes with different surface sensitivities. From the comparison of these signals, we obtain excitation energies for excitonic and ionic surface and bulk states. The energy of the 1s(-1)3p and 1s(-1)4p surface excitation is different by 0.2 eV for the p(z) and the p(xy) symmetry. The ordering of the splitting depends on the principal quantum number.