Optical Rectification at Semiconductor Surfaces

We show that far-infrared radiation can be generated in the depletion field near semiconductor surfaces via the inverse Franz-Keldysh effect or electric-field-induced optical rectification. This mechanism is conceptually different from those previously proposed and accounts for many recent experimental observations

Ultrafast Relaxation of Photoexcited Carriers: The Role of Coherence in the Generation Process

A self-consistent description of the ultrafast dynamics of photoexcited carriers in semiconductors based on a generalized Monte Carlo solution of the semiconductor Bloch equations is presented. The problem of photogeneration and its theoretical description are discussed. We show that some of the approaches commonly used fail in describing correctly the effect of carrier-carrier interaction in the low-density limit. By including terms which have the structure of ‘‘in-scattering'' terms (vertex corrections) for the interband polarization, the experimentally observed features in the carrier dynamics are well described in the whole density range

Far-Infrared Light Generation at Semiconductor Surfaces and its Spectroscopic Applications

Femtosecond pulses of far-infrared (FIR) radiation can be generated in the depletion field near semiconductor surfaces under optical excitation via the inverse Franz-Keldysh effect or electric-field-induced optical rectification. This coherent mechanism differs from previously proposed incoherent mechanisms and is expected to dominate for nonresonant excitation as well as for resonant excitation with optical fields. Two femtosecond time-resolved spectroscopic applications using a visible excitation pulse and a FIR probe pulse are described

Synthesis of nanocrystalline zinc ferrite powders from sulphuric pickling waste water

A low temperature method was used to synthesise nanocrystalline zinc ferrite powders from sulphuric pickling water (SPW), a waste 31 21 product of the steelmaking industry. The synthesis method consisted of coprecipitation of a bi-ionic Fe /Zn solution with 1M 31 21 n-butylamine. Fe from the SPW and Zn provided by ZnO were mixed at a molar ratio of 2.0. The precursor obtained in this manner showed a 2-line X-ray diffraction pattern similar to that of ferrihydrite. Thermal treatment of the precursor at |375 8C led to the formation of pure, fine-particle and stoichiometric ZnFe O powders. This process allows the total recovery of the iron in the SPW, as a product of 2 4 added value. The fine powders were characterised by XRD, FTIR, TG/DSC and SEM. The BET specific surface and the magnetic properties of the powders were also determined.The authors would like to thank the European Commission (Convention 7261/02/512) and the CICYT (project MAT94-0799 for funding of the study. They are also indebted to Dr. Patricia Crespo of the Facultad de Ciencias F´ısicas (UCM) for performing the magnetic determinations.Peer reviewe

Personal Factors Classification Revisited : A Proposal in the Light of the Biopsychosocial Model of the World Health Organization (WHO)

In 2010, we proposed a personal factor classification which was published in this journal. Since then, the International Classification of Functioning, Disability and Health (ICF) of the World Health Organization (WHO) and the biopsychosocial model were increasingly incorporated into the German Social Law Code for participation and rehabilitation, implying that personal factors are indispensable for individual assessments. For the present study, we aimed to come up with an updated version of the personal factors classification based on current research. To achieve this goal, we employed a qualitative approach to re-examine the basic structure, consistency, and selection of categories in the classification from our 2010 study, to amend and supplement the categories to reflect best practice personal factor classifications. Our findings indicate that the basic structure remained largely unchanged, with relatively minor changes, including the deletion of 5 categories from our 2010 classification, 10 categories revised in format or content, and 13 new categories. We believe our revised classification to be useful for supporting users in systematically, comprehensively, and transparently reporting influences on specific aspects of individuals’ life and living background on their functioning and participation, thus facilitating an equitable allocation of disability benefits