Phonon-like and single particle dynamics in liquid lithium

The dynamic structure factor, S(Q,E), of liquid lithium (T=475 K) has been determined by inelastic x-ray scattering (IXS) in the momentum transfer region (Q = 1.4-110 nm-1). These data allow to observe how, in a simple liquid, a phonon-like collective mode evolves towards the single particle dynamics. As a function of Q, one finds: i) at low Q's, a sound mode with a positive dispersion of the sound velocity, ii) at intermediate Q's, excitations whose energy oscillates similarly to phonons in the crystal Brillouin zones, and iii) at high Q's, the S(Q,E) approaches a Gaussian shape, indicating that the single particle dynamics has been reached.Comment: 3 pages and 5 figure

Electrochemical and photoelectrochemical study of pure and iron implanted copper in alkaline medium

An electrochemical and photoelectrochemical study of pure and iron implanted copper in alkaline solution has been performed by means of: - photopotential measurements at different electrodic voltages; - voltammetric curves tracing, in order to reveale the effects induced by light on the current; - polarization resistance (Rp) measurements, in order to determine the corrosion rate of the electrodes. The reduction mechanism on pure copper are discussed. Iron, entering the surface oxide lattice in iron implanted copper, stabilizes the passive film in alkaline solution