Interlayer conduction band states in graphite-sulfur composites

We present experimental evidence for the existence of interlayer states formed in graphite-sulfur (C-S) composites. We have studied occupied and unoccupied p bands of the C-S composites by means of soft x-ray absorption and emission spectroscopy. New spectral features in the C 1s absorption are interpreted as contributions arising from the interaction of sulfur s states with graphite interlayer states. The equivalence of C Kalpha x-ray emission spectra of C-S and graphite lets us conclude that the interlayer states are entirely located above the Fermi level.661

Co 3d-level position in ZnS : Co semiconductors

Experimental studies of x-ray photoelectron and Co Lalpha x-ray emission spectra of the ZnS:Co semiconductor were carried out. It was established that Co ions are present in isovalent Co2+ configuration and that the Co 3d impurity states are localized above the top of the valence band by 1.0 +/- 0.2 eV

Gravitational bremsstrahlung in ultra-planckian collisions

A classical computation of gravitational bremsstrahlung in ultra-planckian collisions of massive point particles is presented in an arbitrary number d of toroidal or non-compact extra dimensions. Our method generalizes the post-linear formalism of General Relativity to the multidimensional case. The total emitted energy, as well as its angular and frequency distribution are discussed in detail. In terms of the gravitational radius r_S of the collision energy, the impact parameter b and the Lorentz factor in the CM frame, the leading order radiation efficiency in the Lab frame is shown to be of order (r_S/b)^{3(d+1)} gamma_{cm} for d=0, 1 and of order (r_S/b)^{3(d+1)} gamma_{cm}^{2d-3} for d>1, up to a known d-dependent coefficient and a ln gamma_{cm} factor for d=2, while the characteristic frequency of the radiation is gamma/b. The contribution of the low frequency part of the radiation (soft gravitons) to the total radiated energy is shown to be negligible for all values of d. The domain of validity of the classical result is discussed. Finally, it is shown that within the region of validity of our approach the efficiency can obtain unnatural values greater than one, which is interpreted to mean that the peripheral ultra-planckian collisions should be strongly radiation damped