A technological complex for manufacturing of precise imaging optics

A comprehensive approach to solving the problem of creating supersmooth optical surfaces with subnanometer accuracy is described. In this work, we create a production process that includes the certification of optical elements, finishing shapes to the required parameters while preserving the atomic smoothness of the surface, and the deposition of multilayered reflecting coverings with internal stresses compensated for.     

Modelling of 980 nm pumped EDWAs: Spectroscopic variations associated to fabrication process

In this work the optical amplification, in the small signal regime, at 1.5 m in Zn-diffused, proton exchange and reverse proton exchange Er³⁺-doped waveguide amplifiers (EDWAs) based on LiNbO₃ under 980 nm excitation has been modelled, including the dominant up-conversion channel activated by this pumping wavelength. The overlapping integrals method has been used to investigate how the spectroscopic changes, induced by the waveguide fabrication technique, affect the optical amplifier performance. In particular, it has been found that either the amplifier threshold and the maximum gain achievable are spectroscopy-dependent and therefore fabrication-dependent.     

Characterization and optimization of the laser-produced plasma EUV source at 13.5 nm based on a double-stream Xe/He gas puff target

The paper describes a debris-free, efficient laser-produced plasma source emitting EUV radiation. The source is based on a double-stream Xe/He gas-puff. Its properties and spectroscopic signatures are characterized and discussed. The spatio-spectral features of the EUV emission are investigated. We show a large body of results related to the intensity and brightness of the EUV emission, its spatial, temporal, and angular behavior and the effect of the repetition rate as well. A conversion efficiency of laser energy into EUV in-band energy at 13.5 nm of 0.42% has been gained. The electron temperature and electron density of the source were estimated by means of a novel method using the FLY code. The experimental data and the Hullac code calculations are compared and discussed. The source is well suited for EUV metrology purposes. The potential of the source for application in EUV lithography was earlier demonstrated in the optical characterization of Mo/Si multi-layer mirrors and photo-etching of polymers.     

Hysteresis of a solar EUV flux and the relation of its characteristics to the solar cycle amplitude

The phenomenon of a difference between solar EVV fluxesI (<130 nm) measured for the same solar indices but in cycles of different amplitudes is studied. The difference can reach 15–20%. The phenomenon is explained in terms of a two-component model of solar EUV variations (from the active regions and the undisturbed solar surface). It follows from this model that in powerful cycles the fluxesI must be greater than in weak cycles for the same solar index F_10.7. The results of the HI line measurements from SME are presented as an example of the possibility of solar cycle amplitude prediction about two years before the solar maximum epoch.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 10, pp. 1237–1241, October, 1996.     

The Lund fragmentation process for a multi-gluon string according to the area law

The Lund area law describes the probability for the production of a set of colourless hadrons from an initial set of partons, in the Lund string fragmentation model. It was derived from classical probability concepts but has later been interpreted as the result of gauge invariance in terms of the Wilson gauge loop integrals. In this paper {we will present a general method to implement the area law for a multi-gluon string state}. In this case the world surface of the massless relativistic string is a geometrically bent (1+1)-dimensional surface embedded in the (1+3)-dimensional Minkowski space. The partonic states are in general given by a perturbative QCD cascade and are consequently defined only down to a cutoff in the energy-momentum fluctuations. We will show that our method defines the states down to the hadronic mass scale inside an analytically calculable scenario. We will then show that there is a differential version of our process which is closely related to the generalized rapidity range , which has been used as a measure on the partonic states. We identify as the area spanned between the directrix curve (the curve given by the parton energy-momentum vectors laid out in colour order, which determines the string surface) and the average curve (to be called the -curve) of the stochastic X-curves (curves obtained when the hadronic energy-momentum vectors are laid out in rank order). Finally {we show that from the X-curve corresponding to a particular stochastic fragmentation situation it is possible to reproduce the directrix curve} (up to one starting vector and a set of sign choices, one for each hadron). This relationship provides an analytical formulation of the notion of parton–hadron duality. The whole effort is made in order to get a new handle to treat the transition region between where we expect perturbative QCD to work and where the hadronic features become noticeable. Received: 3 July 2001 / Published online: 31 August 2001     

Development of a target for laser-produced plasma EUV light source using Sn nano-particles

Nano-structured and tin-based targets have been fabricated by the pulsed-laser ablation method, in order to develop efficient and debris-free targets for the laser-produced plasma extreme ultraviolet (EUV) light source at 13.5 nm. Characteristic spectra that have the radiation peak around 13.5 nm were obtained from CO₂ laser produced plasma using the films as a target. A nano-structured target produced EUV light as intense as a bulk target and a narrower line spectrum at 13.5 nm than a bulk target. PACS 32.30.Rj; 52.38.-r; 52.38.Mf; 61.46.+w; 68.37.-d     

Bismuth-doped silica-based fiber lasers operating between 1389 and 1538 nm with output power of up to 22 W

An efficient CW bismuth fiber laser operating around 1.46 μm with an efficiency of >50% and an output power of >20 W has been developed on a bismuth-doped GeO(2)-SiO(2) fiber. The laser demonstrates weak dependence of the output power on temperature in comparison with bismuth lasers operating near 1.15 and 1.3 μm. The laser generation has been obtained in the range 1.39 to 1.54 μm. The first linearly polarized bismuth-doped fiber laser at 1.46 μm based on a PANDA-type fiber has been demonstrated.     

The investigation of the reaction22Na(n,p)22Ne for a neutron energy to 1,000 eV

TheK-internal conversion coefficient of the 205 keV (7/2⁺→5/2⁺) transition in¹⁰⁷Cd was determined. From the measured value α _K =0.0552±0.0009 and the known value of theE2/M1 mixing ratio δ² a value of 6.3±1.5 was deduced for the penetration parameterλ. Information derived on effective gyromagnetic ratios in the frame of an extreme single particle model is briefly discussed.     

Self-organization of a system of dipole particles according to the keesom model

Self-organization of dipolar hard spherical particles at low temperatures was studied using the Monte Carlo method. Configurations of the principal stable structures formed by the particles upon the destabilization of homogeneous distribution were described. The possibility of the formation of structural domains of different symmetries and sizes commensurate with the volume of the system under certain circumstances was demonstrated. The dipole moment of the domains thus formed is considerably higher than that of the entire system. The existence of dipole interactions in the model apparently leads to the appearance of layered structures. The results we obtained can be used in the development of biotechnologies involving the use of synthetic magnetic particles for targeted delivery of chemotherapeutics into an affected organ, as contrast agents in magnetic resonance imaging, and for the studies of magnitotaxis mechanisms.     

Ising model for the alloys according to the effective field theory

FeAl alloys in their disordered structural phase have been investigated through an Ising model where besides exchange interactions between nearest-neighbors Fe atoms, a superexchange interaction mediated by Al atoms is also taken into account. The model has been approximately treated according to the effective field theory. Although the phase diagram, as a function of Al concentration, is similar to the one previously obtained from Bogoliubov variational approach for the free energy, a different behavior for the superexchange interaction is achieved, which can also be physically accepted for this system.     

Using sonochemistry for the fabrication of nanomaterials

One of the reasons for the huge interest in nanomaterials originated because of the prohibitive price that commercial companies have to pay for introducing new materials into the market. Nanotechnology enables these companies to obtain new properties using old and recognized materials by just reducing their particle size. For these known materials no government approval has to be obtained. Thus, the interest in nanomaterials has led to the development of many synthetic methods for their fabrication. Sonochemistry is one of the earliest techniques used to prepare nanosized compounds. Suslick, in his original work, sonicated Fe(CO)5 either as a neat liquid or in a decalin solution and obtained 10-20 nm size amorphous iron nanoparticles. A literature search that was conducted by crossing Sono* and Nanop* has found that this area is expanding almost exponentially. It started with two papers published in 1994, two in 1995, and increased to 59 papers in 2002. A few authors have already reviewed the fields of Sono and Nano. It should be mentioned that in 1996, Suslick et al. published an early review on the nanostructured materials generated by ultrasound radiation. Suslick and Price have also reviewed the application of ultrasound to materials science. This review dealt with nanomaterials, but was not directed specifically to this topic. The review concentrated only on the sonochemistry of transition metal carbonyls and catalytic reactions that involve the nanoparticles resulting from their sonochemical decomposition. Grieser and Ashokkumar have also written a review on a similar topic. A former coworker, Zhu, has recently submitted for publication a review article entitled "Novel Methods for Chemical Preparation of Metal Chalcogenide Nanoparticles" in which he reviews three synthetic methods (sonochemistry, sonoelectrochemistry, and microwave heating) and their application in the synthesis of nanosized metal chalcogenides. Although still unpublished, I myself have recently written a review discussing novel methods (sonochemistry, microwave heating, and sonoelectrochemistry) for making nanosized materials. The current review will: (1) Present the four main advantages that sonochemistry has over other methods related to materials science and nanochemistry; (2) concentrate on the more recent (2003) literature that was not reviewed in the previously-mentioned reviews, and (3) focus on a specific question, such as what is the typical shape of products obtained in sonochemistry? This review will not survey the literature related to sonoelectrochemistry.     

Laser Phase Determination and Transfer Function to Directly Measure the Temporal Structure of a Narrow Bandwidth Attosecond EUV Pulse

A laser phase determination method and a transfer function that includes a proportional term of a measured photoelectron energy spectrum are presented to directly measure the detailed temporal structure of a narrow bandwidth attosecond extreme-ultraviolet （EUV） pulse. The method is based on the spectrum measurement of an electron generated by EUV photo-ionization interacting with a femtosecond laser field. The results of the study suggest that measurements should be taken at 0° or 180° with respect to the linear laser polarization. The method has a temporal measurement range of about half a laser oscillation period. The temporal resolution also depends on the jitter and control precision of the laser and EUV pulses.     

Electroplating silver tetracyanoquinodimethane between gold micro-gap electrodes for the fabrication of coplanar devices, a new way to integrate material synthesis and devices fabrication within one step

In this paper we propose a method for the integration of the synthesis of silver-tetracyanoquinodimethane (AgTCNQ) and the fabrication of its devices within one step. The method was performed by electroplating Ag between gold coplanar micro-gap electrodes in tetracyanoquinodimethane (TCNQ) solution. As soon as silver was electrochemically dissolved in the TCNQ solution, it immediately reacted with TCNQ to form AgTCNQ and then deposited between Au gap electrodes. With the continuing of the reaction, the Au micro-gap electrodes were connected by AgTCNQ to form Au/AgTCNQ/Au coplanar gap devices. With this electroplating technique, series gap devices of AgTCNQ were fabricated, and the devices exhibited switching phenomena with good reproducibility. This method integrated the synthesis of AgTCNQ and the fabrication of its devices within a single step, and should be also inspirable for other charge transfer complexes. PACS 81.05.Hd; 81.20.Ka; 82.45.Aa; 82.45.Qr     

A proposal to use a plasma lens to achieve a 12 nm spot at the end of CLIC

Summary We review the use of a wake field plasma lens as the final focusing element at the interaction point of the CERN linear collider (CLIC) scheme. Taking longitudinal and transverse aberrations into account we propose a set of parameters to achieve the design specification of 12 nm spot radius. The authors of this paper have agreed to not receive the proofs for correction.