Surface preparation and characterization of indium tin oxide substrates for organic electroluminescent devices

Received: 10 March 1998 / Accepted: 21 September 1998 / Published online: 24 February 1999     

Hydrogen dissociation on metal surfaces – a model system for reactions on surfaces

Received: 23 March 1998/Accepted: 21 August 1998     

Interaction of atomic hydrogen with metal surfaces

Received: 23 March 1998/Accepted: 21 August 1998     

Spectroscopic process sensors in MOVPE device production

Received: 21 October 1998 / Accepted: 23 October 1998     

Structure and dynamics of clean and adsorbate-covered crystal surfaces studied by surface X-ray diffraction

Received: 24 March 1998/Accepted: 21 August 1998     

On the theory of relaxation of electrons excited by femtosecond laser pulses in thin metallic films

Received: 14 October 1998 / Revised version: 21 December 1998     

Imaging metallic multilayer structures through ultrafast optically driven excited electron transport

Received: 20 September 1998 / Revised version: 21 December 1998     

Incoherent-to-coherent optical conversion by means of azobenzene liquid-crystalline films

Received: 20 July 1998/Revised version: 21 September 1998     

Light transmittance of the layer with cylindrical pores

Received: 20 September 1998 / Revised version: 21 December 1998     

Electric-field modulation measurements of complex electro-optic effects in poled polymer

Received: 10 July 1998/Revised version: 21 September 1998     

Long-term existence of a solid surface under temperature above melting point. Is it possible?

Received: 21 November 1997/Accepted: 1 April 1998     

Effects of a modulation of the pump-polarization in a degenerate pump/probe experiment

The effects of the pump-polarization in a degenerate pump/probe experiment are analyzed. It is shown that modulating the pump polarization from linear to circular induces a modulation in the probe absorption change that allows to separate various contributions that are mixed in the signal. An experimental demonstration is carried out in a laser dye (Coumarin 500). Received: 21 July 1998 / Revised: 28 October 1998 / Accepted: 20 November 1998     

Chain radius dependence on concentration in a 2D living polymer system

A living polymer system is used to study the effect of concentration on a broad, polydisperse two-dimensional polymer system. It is found that the mean squared end-to-end radius of a chain of L monomers does not decrease by following a simple power law of the concentration but by a function of the form . An origin for such a behaviour is proposed. Received: 21 November 1997 / Received in final form: 21 April 1998 / Accepted: 24 April 1998     

Field theoretical calculation of the specific heat exponent for a classical N-vector model in a random external field

We calculate using diagrammatic perturbation theory in the two-loop approximation, the specific heat exponent for the classical N-vector model in a random external field for spatial dimension (D) lying between four and six. The calculation supports the modified hyperscaling , where is the correlation length exponent. Received: 18 March 1998 / Revised: 17 April 1998 / Accepted: 21 April 1998     

Effect of the initial phase of the field in ionization by ultrashort laser pulses

We report on observable new features related to ionization of atoms by laser pulses of only few cycles and some intensity. We show that for particular photo-electron energies, the angular distribution becomes asymmetric and that this asymmetry is related to the initial phase of the field. Received: 4 November 1997/Revised: 21 January 1998/Accepted: 23 February 1998     

Calculation of Wannier-Bloch and Wannier-Stark states

The paper discusses the metastable states of a quantum particle in a periodic potential under a constant force (the model of a crystal electron in a homogeneous electric field), which are known as the Wannier-Stark ladder of resonances. An efficient procedure to find the positions and widths of resonances is suggested and illustrated by numerical calculations for a cosine potential, which are in excellent agreement with complex scaling resonance energies. Received: 27 April 1998 / Revised: 21 July 1998 / Accepted: 3 August 1998     

A novel electrochemical approach for fabrication of photoluminescent erbium-doped porous silicon

21 /cm³. After this new ECD treatment, PS:Er was found to emit much more intense room-temperature visible photoluminescence than both the porous silicon control and the PS:Er prepared by constant-current ECD. Room-temperature IR photoluminescence around 1.54 μm was observed for the first time without any post-doping annealing. Received: 3 September 1998/Accepted: 9 September 1998     

Coulomb blockade of the persistent current in a one-dimensional ballistic Luttinger liquid ring

The effect of an electrostatic energy (in the geometrical capacitance approach) on a persistent current is considered. It is shown that at high temperatures the current amplitude shows periodic dips as a function of the potential difference between a ring and a reservoir. These dips correspond to a lift of the Coulomb blockade. In a minimum of a dips a current is periodic in a magnetic flux with a period at any temperatures. Received: 6 April 1998 / Revised: 5 June 1998 / Accepted: 21 July 1998     

On Kreimer's Hopf algebra structure of Feynman graphs

We reinvestigate Kreimer's Hopf algebra structure of perturbative quantum field theories with a special emphasis on overlapping divergences. Kreimer first disentangles overlapping divergences into a linear combination of disjoint and nested ones and then tackles that linear combination by the Hopf algebra operations. We present a formulation where the Hopf algebra operations are directly defined on any type of divergence. We explain the precise relation to Kreimer's Hopf algebra and obtain thereby a characterization of their primitive elements. Received: 9 July 1998 / Revised version: 21 September 1998 / Published online: 19 November 1998     

A Fourier optics model of two-beam scanning laser interferometers

The article illustrates the use of Fourier optics to describe the operation of two-beam scanning laser interferometers. It deals with the effect of diffraction on the spatial periodicity of a monochromatic and coherent beam. Particular attention is given to the analysis of systematic errors in high-accuracy laser metrology. The article reviews the special case of plane wave and Gaussian illuminations, examines how beam truncation affects the period of traveling fringes and presents a general relation between the relative wavelength deviation and the impulse standard deviation of the photons. Received: 18 February 1998 / Revised: 21 October 1998 / Accepted: 16 November 1998