The unusual magnetic properties of thin films of Fe 1−x Co x O y {0 x 1} ferrite solid solutions have been explained through an investigation of their electronic structure. The x-ray absorption near-edge structure (XANES) spectra of the Fe L 3 -edge and K-edges show that Co replaces Fe 3+ in the tetrahedral (T d ) sites up to x = 0.34 and octahedral (O h ) sites from 0.39 < x < 0.89. The Co L 3 -edge and O K-edge results indicate mixed valence states of Co as it replaces Fe at dissimilar sites. From the results, it is concluded that the magnetic properties of the thin films of the spinel Fe 1−x Co x O y arise from the Fe 3+ at the T d sites. The replacement of Fe 3+ and Fe 2+ by Co at the O h sites results in a crossover to the rocksalt structure and a loss of the magnetic properties.

BNL has been developing a remote sensing technique for the detection of atmospheric pollutants based on the phenomenon of resonance Raman LIDAR that has also incorporated a number of new techniquedtechnologies designed to extend it's performance envelope. When the excitation frequency approaches an allowed electronic transition of the molecule, an enormous enhancement of the inelastic scattering cross-section can occur, ORen up to 2 to 4 orders-of -magnitude, and is referred to as resonance Raman (RR), since the excitation frequency is in "resonance" w i t h an allowed electronic transition. Exploitation of this enhancement along with new techniques such as pattern recognition algorithms to take advantage of the spectral fingerprint and a new laser fiequency modulation technique designed to suppress broadband fluorescence, referred to as Frequency-Modulated Exutation-Raman Spectroscopy (FteMERs) and recent developments in liquid edge filter technology, for suppression of the elastic channel, all help increase the overall performance of h a n LIDAR Introduction: