Search

A near 1-keV photons from the Xe/He plasma produced by the interaction of laser beam with a double stream gas puff target were employed for studies of L absorption edges of period 4 transitional metals with atomic number Z from 26 to 30. The dual-channel, compact NEXAFS system was employed for the acquisition of the absorption spectra. L1–3 absorption edges of the samples were identified in transmission mode using broadband emission from the Xe/He plasma to show the applicability of such source and measurement system to the NEXAFS studies of the transition metals, including magnetic materials.

The size and shape of biological particles are important parameters allowing discrimination between various species. We have studied several aerosols of biological origin such as pollens, bacterial spores and vegetative bacteria. All of them presented different morphology. Using optical size and shape analyser we found good correlation between light scattering properties and actual particle features determined by scanning electron and fluorescence microscopy. In this study, we demonstrated that HCA (Hierarchical Cluster Analysis) offers fast and continuous bioaerosol classification based on shape and size data matrices of aerosols. The HCA gives an unequivocal interpretation of particle size vs. asymmetry data. Therefore, it may provide high throughput and reliable screening and classification of bioaerosols using scattering characteristics. Keywords: bioaerosol classification, scattering, particle size and shape analysis, biological warfare agents’ detection, hierarchical cluster analysis (HCA)

In this work investigations concerning interaction of intense, nanosecond EUV pulses with matter were performed. Various laser-produced plasma radiation sources were employed for creation of the driving EUV pulses. The sources were based on two different laser systems with pulse energies ranging from 0.8 J to 10J and pulse duration 4 ÷ 10 ns. They were equipped with the EUV collectors for focusing of the radiation. This way radiation fluence up to 0.5 J/cm2 in the interaction region was obtained. In our experiments solid material samples or gases injected into the vacuum chamber synchronously with the EUV pulses were irradiated. Irradiation of the gases resulted in ionization and excitation of atoms and molecules forming low temperature plasmas with a relatively high electron density. Emission spectra obtained from these plasmas, contained spectral lines corresponding to radiative transitions in atoms, molecules, atomic or molecular ions. For analysis of the EUV spectra numerical simulations were performed, using a collisional-radiative PrismSPECT code. For computer simulations of the molecular spectra measured in the UV/VIS range a LIFBASE and Specair codes were employed. This way ionization states together with various thermodynamic parameters were deduced. Irradiation of solid samples resulted in melting of a thin near-surface layer or, in some cases its ablation or even conversion to a low temperature plasma. It depended on physico-chemical properties of the material and its thickness. In case of organic polymers, usually ablation connected with fragmentation of the polymer molecules, took place. In case of thick samples of inorganic solids, a thin near surface layer was heated up to a high temperature exceeding melting or even boiling point. In most cases different kinds of micro- or nanostructures were created, modifying the surface morphology. Except the EUV interaction with solid materials, simultaneous EUV and the EUV induced plasma treatment was investigated. Plasmas were created in gases injected close to the exposed surface. Part of the EUV radiation was absorbed in the injected gas forming the low temperature plasma near the surface, while the other part of radiation, that was not absorbed, interacted with the surface material. This way additional atoms could be incorporated into the molecular structure of the exposed material, or reactive etching took place. Especially interesting results were obtained using molecular gases for creation the reactive plasmas.

A desktop tomography system, based on laser-interaction with a gas puff target, which results in efficient plasma formation emitting in the soft X-ray (SXR, λ = 0.1 - 10 nm) region, was developed at IOE-WAT (Warsaw, Poland). The system, coupled with an ellipsoidal condenser and a Fresnel zone-plate and working in the "water window" spectral range (λ = 2.3 - 4.4 nm) at the quasi-monochromatic He-like nitrogen spectral line (λ=2.88nm), allows acquiring images approaching a resolution of few microns. The development of such setup offers the possibility to obtain a reconstruction of three-dimensional images in a laboratory environment, without the involvement of large "photon facilities". Details about the system and its optimization as well as some imaged samples will be presented and discussed.

Background The accessibility of the remineralizing ions in teeth's environment is essential for their incorporation into caries-affected dentin. Novel bioglass-reinforced materials capable of releasing fluoride, calcium and phosphates may be particularly useful in the tissue remineralization process. A novel restorative material, ACTIVA BioActive-Restorative (Pulpdent Corp., Watertown, USA), is a hydrophilic resin-modified glassionomer cement (RMGIC) enriched with bioglass particles and fortified with a patented rubberized polymer resin. Its application in restorative dentistry may be significant, promoting remineralization of carious lesions. Objectives The aim of the study was to compare the fluoride ion release profiles from a bioglass-reinforced RMGIC, a conventional glass-ionomer cement (GIC) and a nanohybrid restorative polymer resin. Material and methods The quantity of fluoride ions released from ACTIVA, Ketac Molar Quick Aplicap and Tetric EvoCeram was assessed using a fluoride-specific electrode. The surface characteristics of the preand post-experimental specimens were studied using a scanning electron microscope (SEM) and confocal microscope. An X-ray powder diffraction (XRD) analysis was additionally used to examine the chemical compositions of the dental materials. Results The greatest quantity of fluoride ions was freed from the GIC specimens (20.698-54.118 ppm), followed by the bioglass-reinforced RMGIC (from 1.236 to 15.552 ppm) and nanohybrid polymer resin (0.370-1.148 ppm). The pre-experimental specimens of the bioglass-reinforced RMGIC were porous, while the post-experimental specimens were smoother with visible micro-cracks. The XRD analysis of the bioglass particles confirmed that the material was composed mainly of fluoride (27.70 mass%), silicon (15.62 mass%), aluminum (5.91 mass%), and calcium (5.40 mass%). Conclusions The fluoride ion release profile of ACTIVA was lower than the GIC Keta Molar Quick Aplicap, but significantly higher than the nanohybrid restorative polymer resin Tetric EvoCeram.

Low temperature plasmas induced by irradiation of molecular gases with extreme ultraviolet (EUV) pulses were studied. The EUV pulsed beams of high intensity, were formed using laser-produced plasma (LPP) sources, based on Nd:YAG laser systems and a double-stream Xe/He gas-puff target. The EUV beams were used for irradiation of small portions of gases, injected into a vacuum chamber synchronously with the radiation pulses. Low temperature plasmas produced this way in oxygen, nitrogen or sulfur hexafluoride gas emitted radiation in a wide spectral range. The corresponding EUV spectra were dominated by emission lines originating from singly charged, atomic ions. In case of spectra recorded in an optical range, emission lines, corresponding to radiative transitions in atomic or molecular species, were detected. Taking into account a Stark broadening of F I emission lines an electron density was estimated. Its value exceeded 1017cm-3, which is a few orders of magnitude higher comparing to plasmas produced in standard generators. Employing the SF6 – based plasmas an experiment concerning plasma treatment of a silicon surface was performed. A possibility to create different kinds of nanostructures was demonstrated.

BACKGROUND: Radioiodine therapy (RIT) in patients with large nontoxic multinodular goiter (MNG) recently becomes more common method in comparison to surgery (especially in elderly patients and with contraindications because of severe chronic diseases other systems). Repeatedly low thyroid radioactive iodine uptake (RAIU) decreases effectiveness of RIT or makes it impossible. The recombinant human thyrotropin can increase RAIU and improve the results of RIT. The aim of the study was to assess the influence of a single very low dose (0.03 mg) of rhTSH on RAIU and thyroid function in euthyroid (MNG-EU) and subclinical hyperthyroid (MNG-SC) patients with a large multinodular goiter. MATERIAL AND METHODS: 40 patients (14 male, 26 female, age 57–80 yr) with large non-toxic MNG over 80 grams and with baseline RAIU < 40% were included into the double-blind randomized study and divided into two groups: rhTSH-group and control group. First group received the single intramuscular injection of 0.03 mg rhTSH and the second received placebo. The RAIU were measured 24 and 48 hours after the rhTSH and then all the patients were administered therapeutic doses of I-131. TSH and free thyroxine levels were measured at 1st and 2nd day after the injection of rhTSH and later, at 4 and 8 weeks after the RIT. RESULTS: The mean RAIU increased significantly from 30.44 ± 7.4% to 77.22 ± 8.7% (p < 0.001). There were no statistically significant differences in RAIU between euthyroid (MNG-EU) and subclinically hyperthyroid (MNG-SC) patients. The peak of serum TSH was noticed 24 hours after rhTSH injection and in MNG-EU patients it has remained within normal range, similarly as fT4. In the MNG-SC group the administration of rhTSH resulted in a significant increase in the TSH values after 24 hours, whose mean level slightly exceeded the upper limit of the normal range with normalization at 48 hours. 8 weeks after the RIT, the TSH and fT4 levels did not exceed the normal range and did not differ in a statistically significant way. Conclusions: Even the single very low dose of rhTSH increases the values of RAIU in significant way, in euthyroid and subclinically hyperthyroid patients. The administration of rhTSH is well-tolerated. Neoadjuvant administration of a low dose (0.03 mg) of rhTSH before I-131 seems to be an optimal method of management which may increase the effectiveness of RIT and decrease the exposure of the patients to absorbed doses of ionizing radiation.

We present a few examples of imaging experiments, which were possible using a compact laser-plasma extreme ultraviolet (EUV) and soft X-ray (SXR) source, based on a double stream gas puff target. This debris-free source was used in full-field EUV imaging to obtain magnified images of test samples, ZnO nanofibers and images of the membranes coated with salt crystals. The source was also employed for SXR microscopy in the “water-window” spectral range using grazing incidence Wolter type-I objective to image test samples and to perform the initial studies of biological objects. Gas puff target EUV source, spectrally tuned for 13.5 nm wavelength with multilayer mirror and thin film filters, was also used in variety of shadowgraphy experiments to study the density of newly developed modulated density gas puff targets. Finally, the source was also employed in EUV tomography experiments of low density objects with the goal to measure and optimize the density of the targets dedicated to high harmonic generation.

We present a 2-D mapping of a sample thickness with nanometer accuracy employing a compact arrangement of near-edge X-ray absorption fine structure (NEXAFS) technique. A NEXAFS spectrum coupled with a scanning system was used to generate a 2-D thickness map of the TiO2 sample (anatase form) deposited on the top of a SiN membrane. The thickness values were retrieved from the experimental data by applying different methods of data processing. In the paper, the detailed analysis of the data processing methods and the identified sources of the errors show that the proposed procedure based on averaging two imperfect estimates reduces the error caused by the uncontrolled bias of the measured signals. This procedure was termed as the average one. The estimates from the proposed average approach and the standard absorption-jump ratio in the absorption edge vicinity were compared with the direct results obtained by applying scanning electron microscopy (SEM). The experimental arrangement of the NEXAFS spectroscopy system, the data acquisition method, as well as the possible error sources, are presented and discussed in detail.

Application of a compact laser plasma source of soft X-rays and extreme ultraviolet (EUV) in imaging with nanometer resolution is demonstrated. The source is based on a gas puff target irradiated with nanosecond laser pulses from a small commercial Nd:YAG laser. Soft X-ray radiation in the ‘water window’ spectral range and EUV near 10 nm are generated efficiently without production of target debris. Nanoscale imaging of biological samples as well as micro- and nanostructures using transmission soft X-ray and EUV microscopy based on Fresnel optics and soft X-ray contact microscopy is demonstrated.

Introduction: Radioiodine (131I) isotope therapy is the method of choice in the treatment of Graves’ disease relapse. The efficiency of this method is dependent on many factors; therefore, the present paper aims to identify the parameters that have a crucial impact on the efficacy of radioiodine therapy for Graves’ disease. Material and methods: The authors performed a retrospective analysis of the medical documentation of 700 Graves’ disease sufferers treated with131I. The patients were divided into three groups depending on the thyroid-absorbed dose of 131I: group I — 100 Gy, II — 150 Gy, and III — 200 Gy. The authors assessed the influence of gender, age, presence of orbitopathy, TRab titres, thyroid mass, iodine uptake after 24 and 48 hours, and the absorbed dose on the treatment efficacy at one year post-131I administration. Results: The volume of thyroid gland (P 50 mL, the percentage of hyperthyroidism was lowest in group III (10%). Conclusions: The absorbed dose of 131I and the volume of the thyroid gland are two parameters that have a significant influence on the efficacy of radioiodine therapy for Graves’ disease. 150 Gy is the optimal dose for glands 50 mL requires an absorbed dose of 200 Gy in order to minimise the risk of recurrent hyperthyroidism. (Endokrynol Pol 2015; 66 (2): 126–131)

The results of formation of elongated krypton/helium plasma channels are presented. Two laser pulses were used: one to produce plasma channels and the second one for conversion to soft X rays. The soft X-ray radiation was in turn used for backlighting the channels and their visualization. The study of their formation and uniformity was performed using a combination of soft X-ray shadowgraphy and pinhole camera imaging. The plasma channels, with various lengths and various densities, were visualized and the results of their characterization are presented. Using moderate laser pulse energy quite uniform channels, up to 9 mm in length, were demonstrated.

Characterization measurements of a pulsed capillary channel gas puff target, developed for applications in laser-matter interaction experiments, are presented. The target is produced by pulsed injection of gas through a slit-shaped nozzle into a capillary channel and has been characterized by EUV radiography at 13.5 nm wavelength. Time dependent gas flow effects and flow shaping by capillary walls were visualized. Density measurements for argon were performed on axis for variable timing conditions and variable backing pressures. This target, due to its advantages, might be an interesting alternative for lower repetition rate and higher energy laser-matter interaction experiments.

In this paper, we present the first measurements of the partial spatial coherence of the EUV emission from xenon plasma in laser-plasma source, based on a double stream gas puff target. The Young double slit approach was employed to measure complex coherence factor of the EUV Xe emission at 13.5-nm wavelength in two orthogonal directions. The radius of coherence of ~60 μm was estimated at the distance of 2.1 m from the source. The number of coherently emitted photons was sufficient to demonstrate coherent imaging. Using partially coherent radiation from such source Gabor EUV holography was successfully demonstrated.

Graves' orbitopathy (GO) is characterized by orbital T cell infiltration. We evaluated the regulatory T (Treg) cell fractions induced with IGF-1 in Graves' disease (GD) with and without GO. Peripheral blood mononuclear cells (PBMCs) were obtained from 13 patients with GD without eye manifestations; 10 patients with active GO; and 12 patients with nodular goiter (NG). All the patients from GD, GO, and NG were subclinical hyperthyroid. We analyzed the expression of Treg cell markers (CD4, CD25, CD127-, Foxp3) on T cells and their ability to respond to IGF-1 stimulation. In patients with GD without GO, we found lowered percentages of CD4+ Foxp3+ cells, as compared to nodular goiter 1.77 vs. 5.42% (p=0.0276). Similarly, significantly reduced frequencies of CD4+CD25+CD127-Foxp3+ and CD4+CD25+CD127- cells were observed in GD patients as compared to nodular goiter patients with hyperthyreosis, (0.7 vs. 1.48%) (p=0.0071) and (14.5 vs. 37.2%) (p=0.0051), respectively. In GO with active GO, only the percentage of CD4+CD25+CD127- cells was found to be decreased versus nodular goiter (9.35 vs. 37.2) (p=0.0275). Stimulation of PBMC derived from GO patients with IGF-1 resulted in significant increase of frequency of both CD4+ Foxp3+ and CD4+CD25+CD127- Foxp3 cells. Decreased frequencies of peripheral blood CD4+CD25+CD127-Foxp3+ in patients with GD and GO could be an useful marker of autoimmune process and perhaps a possible target for future therapies. This is the first study demonstrating Treg-enhancing effects of IGF-1. Thus IGF-1 can be accounted for modulating Treg cell-related action in GO.

Polycarbonate Polymer Surface Modi cation by Extreme Ultraviolet (EUV) Radiation I.U. Ahada,b,∗, B. Budner, B. Korczyc, H. Fiedorowicz, A. Bartnik, J. Kostecki, S. Burdy«ska and D. Brabazon Institute of Optoelectronics, Military University of Technology, S. Kaliskiego 2, 00-908 Warszawa, Poland Advanced Processing Technology Research Centre, School of Mechanical and Manufacturing Engineering Faculty of Engineering & Computing, Dublin City University, Dublin 9, Ireland

Allergic rhinitis, also known as hay fever is a type of inflammation which occurs when the immune system overreacts to allergens in the air. It became the most common disease among people. It became important to monitor air content for the presence of a particular type of allergen. For the purposes of environmental monitoring there is a need to widen the group of traditional methods of identification of pollen for faster and more accurate research systems. The aim of the work was the characterization and classification of certain types of plant pollens by using laser optical methods, which were supported by the chemmometrics. Several species of pollen were examined, for which a database of spectral characteristics was created, using LIF, Raman scattering and FTIR methods. Spectral database contains characteristics of both common allergens and pollen of minor importance. Based on registered spectra, statistical analysis was made, which allows the classification of the tested pollen species. For the study of the emission spectra Nd:YAG laser was used with the fourth harmonic generation (266 nm) and GaN diode laser (375 nm). For Raman scattering spectra spectrometer Nicolet IS-50 with a excitation wavelength of 1064 nm was used. The FTIR spectra, recorded in the mid infrared 1 range (4000-650 cm -1 ) were collected with use of transmission mode (KBr pellet), ATR and DRIFT.

New developments in nanoscience and nanotechnology require nanometer scale resolution imaging tools and techniques such as an extreme ultraviolet (EUV) and soft X-ray (SXR) microscopy, based on Fresnel zone plates. In this paper, we report on applications of a desk-top microscopy using a laser-plasma EUV source based on a gas-puff target for studies of morphology of thin silicon membranes coated with NaCl crystals and samples composed of ZnO nanofibers.

In this work helium and neon photoionization experiments, using a laser-plasma EUV (extreme ultraviolet) source were performed. The EUV radiation was focused onto a gas stream, injected into a vacuum chamber synchronously with the EUV pulse. The most intense emission from the source spanned a relatively narrow spectral region centered at λ =11±1 nm, however, spectrally integrated intensity at longer wavelengths was also significant. Additionally Zr and Al filters were used to narrow the irradiation spectrum and to change the irradiation conditions. Irradiation of gases resulted in EUV luminescence, acquired by a toroidal grating spectrometer. The dominating spectral lines originate from singly charged ions, however, Ne III lines were also detected. Significant differences were observed between spectra obtained for different irradiation conditions. The differences were mainly due to various possibilities of photoexcitation of corresponding states depending on energy distribution of irradiating photons.

Polymeric biomaterials are being widely used for the treatment of various traumata, diseases and defects in human beings due to ease in their synthesis. As biomaterials have direct interaction with the extracellular environment in the biological world, biocompatibility is a topic of great significance. The introduction or enhancement of biocompatibility in certain polymers is still a challenge to overcome. Polymer biocompatibility can be controlled by surface modification. Various physical and chemical methods (e.g., chemical and plasma treatment, ion implantation, and ultraviolet irradiation etc.) are in use or being developed for the modification of polymer surfaces. However an important limitation in their employment is the alteration of bulk material. Different surface and bulk properties of biomaterials are often desirable for biomedical applications. Because extreme ultraviolet (EUV) radiation penetration is quite limited even in low density mediums, it could be possible to use it for surface modification without influencing the bulk material. This article reviews the degree of biocompatibility of different polymeric biomaterials being currently employed in various biomedical applications, the surface properties required to be modified for biocompatibility control, plasma and laser ablation based surface modification techniques, and research studies indicating possible use of EUV for enhancing biocompatibility.

We report for the first time on a compact, desk-top size, laboratory-type microscopy setup, based on nitrogen gas puff target soft X-ray source, which emits radiation in “water-window” spectral range. The microscope employs Wolter type-I objective and allows capturing magnified images of objects with 850 nm spatial resolution and exposure time as low as a few seconds. Details about the source and the microscope as well as imaging results for test and biological objects are presented and discussed.

Characterization measurements and modes of operation of a novel, dual-gas multi-jet target, developed for experiments on high-order harmonic generation, are presented. The target has been formed by pulsed injection of argon through a nozzle in a form of linearly oriented small orifices. The argon jets were separated with the helium jets formed by injection of helium through alternate orifices in the nozzle. The targets have been characterized by extreme ultraviolet backlighting at 13.5 nm wavelength. Density profiles for this type of targets have been obtained, to our knowledge, for the first time.

A slit-shaped elongated nozzle, capable of forming an extended gas density profile, is presented and studied in detail. Argon and xenon target density backlighting measurements revealed the elongated density profiles with gas density that can be tuned by changing valve backing pressure and valve timing. Two dimensional density maps for Ar and Xe targets, obtained at soft X-ray wavelengths around 7 A, are shown and spatially characterized. Moreover the influence of valve backing pressure and valve timing on gas puff target density is studied. This geometry of the nozzle has potential applications in high harmonic generation for an efficient conversion of femto-second duration, intense infrared pulses to extreme ultraviolet (EUV) region.

In this work results of investigations concerning nanostructuring of polymers and some other solids using a laser-plasma extreme ultraviolet source are presented. The plasma radiation was produced using a gas puff target and focused with a gold-plated grazing incidence ellipsoidal collector. Decomposition process of polymers was investigated using a quadrupole mass spectrometer. Different kinds of microand nanostructures created in near-surface layers of the materials were investigated using scanning electron microscope. Forms of the structures depend on a particular material and the extreme ultraviolet exposure. In case of some polymers even a single shot is sufficient for creation of the visible changes in surface morphology. In case of inorganic solids visible changes require usually the exposure with tens or hundreds of extreme ultraviolet pulses.

Various imaging methods and techniques capable of reaching a nanometer spatial resolution are currentlyunder development. One of them is an extreme ultraviolet microscopy, based on the Fresnel zone plates. Inthis paper a compact, high-repetition, laser-plasma EUV source, with a gas puff target, capable of emittingquasi-monochromatic radiation at 13.8 nm wavelength was used in the first demonstration of a desk-top EUVtransmissionmicroscopywithaspatial(half-pitch)resolutionof50nm. EUVmicroscopyimagesofobjectswithvariousthicknessesandthespatialresolutionmeasurementsusingtheknife-edgetestarepresented.PACS:52.38.Ph,52.50.Dg,41.50.+h,42.30.Va,42.79.Ci

In this paper an efficient micromachining of poly(vinylidene fluoride) (PVDF) by direct photo-etching with a laser-plasma EUV (extreme ultraviolet) source was demonstrated for the first time. Mass spectroscopy was employed to investigate the ablation products and revealed emission of numerous molecular species of C-containing fragments of the polymer chain. Chemical surface changes after irradiation were investigated using X-ray photoelectron spectroscopy (XPS). The XPS spectra obtained for PVDF samples, irradiated with low and high EUV fluence, indicate significant differences between chemical structures in near-surface layers. It was shown that irradiation with low fluence results in defluorination and thus carbon enrichment of the polymer in near-surface layer. In contrary, irradiation with high fluence leads to intense material ablation and hardly modifies the chemical structure of the remaining material.

In this work, a 10 Hz laser-plasma extreme ultraviolet (EUV) source built for surface processing of polymers is presented. The source is based on a double-stream gas puff target created in a vacuum chamber synchronously with the pumping laser pulse. The target is formed by pulsed injection of Kr, Xe or a KrXe gas mixture into a hollow stream of helium. The EUV radiation is focused using a grazing incidence gold-plated ellipsoidal collector. Spectrum of the reflected radiation consists of a narrow feature with intensity maximum at 10–11 nm wavelength and a long-wavelength spectral tail up to 70 nm. The exact spectral distribution depends on a gas applied for plasma creation. To avoid strong absorption of the EUV radiation in a residual gas present in the chamber during the source operation a two step differential pumping system was employed. The system allows for polymer processing under relatively high vacuum conditions (10−5 mbar) or in a reactive gas atmosphere. Polymer samples can be irradiated in a focal plane of the EUV collector or at some distance downstream the focal plane. This way fluence of the EUV beam at the polymer surface can be regulated.

In this work a laser-plasma EUV source based on a gas puff target was used for micro- and nanostructuring of polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and poly-oxydiphenylene-pyromellitimide (Kapton HN) foils. The plasma radiation was focused using a gold-plated grazing incidence ellipsoidal collector. The collector allowed for effective focusing of Kr plasma radiation from the wavelength range λ = 9–70 nm. The polymer foils were irradiated in the focal plane or at some distance downstream the focal plane of the EUV collector. The surface morphology of the irradiated polymer samples was investigated using a scanning electron microscope (SEM) and the chemical changes by X-ray photoelectron spectroscopy (XPS). Different kinds of micro- and nanostructures created in near-surface layers of the polymers were obtained. The form of the structures depends on the type of polymer and the EUV exposure. In case of PEN even a single shot was sufficient to obtain visible changes in surface morphology. In case of Kapton clearly visible surface modification requires tens of EUV pulses. To investigate the changes in the chemical structure XPS spectra, corresponding to the valence band of the polymer samples, were measured. Significant differences were revealed in the XPS spectra of irradiated and not-irradiated polymers showing decrease of functional groups containing oxygen was indicated.

In this paper a new approach to a laser-produced plasma EUV source based on a tin target is presented. A thin layer of pure tin and composite layers consisting of Sn with Si, SiO and LiF are investigated. The target composed of several thin layers produces less debris than the other targets and provides a conversion efficiency (CE) in the 13.5-nm±1% band at least comparable to the CE for the pure tin slab target. The largest CE was observed for the target composed of a mixture of Sn and LiF, due to the fact that lithium, similarly to tin, is a strong emitter at 13.5 nm.

In this work, the radiation from a laser-plasma extreme ultraviolet (EUV) source based on a double-stream gas-puff target was used for surface modification of polyethylene terephthalate (PET). The spectrum of the wide band radiation focused with a gold-coated ellipsoidal collector consisted of a narrow feature with maximum at 10 nm and a long-wavelength tail up to 70 nm. The PET samples were mounted in the focal plane of the EUV collector or at some distance downstream this plane and irradiated for 0.1 s–2 min with 10-Hz repetition rate. The polymer samples after irradiation were rinsed in acetone. Surface morphologies of the PET samples after irradiation were investigated using a scanning electron microscope and atomic force microscope. Different kinds of surface micro- and nanostructures were created as a result of irradiation depending on the EUV fluence and number of pulses. Acetone treatment of the polymer samples after irradiation resulted in formation of additional nanostructures. In this case the nanostructures were revealed even after exposure with a single EUV pulse.

In this work, a comparative study of extreme ultraviolet (EUV) induced low temperature SF6-based plasmas, created using two different irradiation systems, was performed. Both systems utilized laser-produced plasma (LPP) EUV sources. The essential difference between the systems concerned the formation of the driving EUV beam. The first one contained an efficient ellipsoidal EUV collector allowing for focusing of the EUV radiation at a large distance from the LPP source. The spectrum of focused radiation was limited to the long-wavelength part of the total LPP emission, λ > 8 nm, due to the reflective properties of the collector. The second system did not contain any EUV collector. The gas to be ionized was injected in the vicinity of the LPP, at a distance of the order of 10 mm. In both systems, energies of the driving photons were high enough for dissociative ionization of the SF6 molecules and ionization of atoms or even singly charged ions. Plasmas, created due to these processes, were investigated by spectral measurements in the EUV, ultraviolet (UV), and visible (VIS) spectral ranges. These low temperature plasmas were employed for preliminary experiments concerning surface treatment. The formation of pronounced nanostructures on the silicon surface after plasma treatment was demonstrated.

A compact, high-repetition table-top EUV source, based on a gas-puff target, is presented. This source was developed in our group and is capable of emitting quasi-monochromatic radiation at 13.8 nm wavelength with the inverse relative bandwidth of 140 and pulse energies up to ∼1.3 μJ/pulse at 10-Hz repetition rate. The source is debris-free, operates near the lithographic wavelengths and offers the energy density of ∼0.4 mJ/cm2 in each EUV pulse. These three features make the source attractive for lithographic experiments. The timing optimization of the source, its energy per pulse, spectral and spatial distributions are pointed out in detail as well as the enhancement in energy density achievable with a multi-layer collector mirror compared to a planar mirror of equal reflectivity.

We have developed compact, high repetition, table-top soft-X-ray sources, based on a gas puff target, emitting in “water window” spectral range at λ = 2.88 nm from nitrogen gas target or, in 2–4 nm range of wavelengths, from argon gas target. Double stream gas puff target was pumped optically by commercial Nd:YAG laser, energy 0.74 J, pulse time duration 4 ns. Spatial distribution of laser-produced plasma was imaged using a pinhole camera. Using transmission grating spectrometer, argon and nitrogen emission spectra were obtained, showing strong emission in the “water window” spectral range. Using AXUV100 detector the flux measurements of the soft-X-ray pulses were carried out and are presented. These debris free sources are table-top alternative for free electron lasers and synchrotron installations. They can be successfully employed in microscopy, spectroscopy and metrology experiments among others.

Extreme ultraviolet (EUV) radiation is the electromagnetic radiation ranging from vacuum ultraviolet to soft X-rays. A single EUV photon carries enough energy to ionize any atom or molecule. The penetration depth of the radiation in any material is very short, ranging from tens to hundreds nanometers. Intense EUV pulses can remove material from the surface or modify its morphology or/and chemical structure. In this work, the radiation from a laser-plasma EUV source based on a double-stream gas-puff target was used for surface modification of polyethylene terephthalate (PET). The PET samples were irradiated with the EUV pulses emitted from krypton plasma and focused with a gold-plated ellipsoidal collector. The spectrum of the focused radiation covered the wavelength range from 9 to 70 nm. The PET samples were irradiated for 1 s–2 min at a 10-Hz repetition rate. Surface morphology of polymer samples after irradiation was investigated using a scanning electron microscope. Changes in chemical surface structure of the irradiated samples were investigated using an X-ray photoelectron spectroscopy. Different kinds of surface microstructures were obtained depending on the EUV fluence in a single pulse and the total EUV fluence. XPS measurements also revealed a modification of the chemical structure.

Laser plasma with temperature of the order of tens eV can be an efficient source of extreme ultraviolet (EUV). The radiation can be focused using different kind of optics, giving sufficient fluence for some applications. In this work we present results of investigations concerning applications of a laser plasma EUV source based on a double stream gas puff target. The source was equipped with two different grazing incidence collectors. One of them was a multifoil collector, the second one was an axisymmetrical ellipsoidal collector. The multifoil mirror was used mainly in experiments concerning micromachining of organic polymers by direct photo-etching. The experiments were performed for different polymers that were irradiated through a fine metal grid as a contact mask. The smallest element of a pattern structure obtained in this way was 5 μm, while the structure height was 50 μm giving an aspect ratio about 10. The laser-plasma EUV source equipped with the axisymmetrical ellipsoidal collector was used for surface modification of organic polymers and inorganic solids. The surface morphology after irradiation was investigated. Different forms of microand nanostructures were obtained depending on material and irradiation conditions.

Surface modification of PMMA and FEP polymers using extreme ultraviolet (EUV) in two spectral ranges was investigated. A laser-plasma EUV source based on a double stream gas puff target equipped with an Au coated ellipsoidal collector was used for the experiment. The spectrum of the focused radiation from Kr plasma consisted of a narrow feature with a maximum at 10 nm and a long-wavelength tail up to 70 nm. Al and Zr filters were employed for the selection of radiation from these two spectral regions. The radiation fluences in the two cases were comparable. Polymer samples were mounted in the focal plane of the EUV collector and irradiated for 1–2 min with a 10 Hz repetition rate. Weak ablation accompanied by creation of micro- and nanostructures of different kinds was obtained in both cases. Significant differences in the surface structures after irradiation of PMMA and FEP in these two spectral regions were revealed.

In this paper a possibility of performing fluorescence experiments in extreme ultraviolet (EUV) using a laboratory EUV source was demonstrated. Usually such measurements are performed using third-generation synchrotrons because of extremely low probability of fluorescence in this wavelength range. In this work a 10 Hz laser-plasma EUV source based on a gas puff target was used. Fluorescent radiation from Al and Si was registered. Despite relatively low spectral resolution, some differences in Si spectra coming from different kind of samples were revealed.

Extreme ultraviolet (EUV) radiation is absorbed in a thin surface layer of any material. Irradiation of material samples with intense EUV pulses may cause different surface changes. Some of them, especially connected with material desorption, can be clearly visible using an optical or electron microscope. Other changes concerning crystal structure or chemical composition may not be visible under the microscope. They can however be detected using the EUV radiation itself. In this paper a new method of measurement of surface changes by irradiation with a laser-plasma EUV source is presented. The radiation was collected and focused on a material surface using a specially designed multifoil collector. Radiation scattered or excited in the material was detected with the use of a Wolter-type mirror coupled to a back-illuminated CCD camera. Depending on material samples, images with different intensity distributions were registered. For some samples, the intensity distributions of the images obtained before and after irradiation were slightly different. The intensity differences in such cases allowed us to obtain differential images. The appearance of such images was assumed to be evidence of surface changes.

The paper presents the results of investigation of ns-laser pulse interaction with Ni-TiC sample. The present study investigates the effects of the irradiation parameters on the microstructure and surface in-situ composites obtained by the high temperature solution method (HTS). The obtained ingots were irradiated with Nd:YAG laser pulses (Quantel Brio, 4ns, 70mJ@1.06μm), focused with a lens of the focal length of 10 cm in air conditions. Microstructure of the laser irradiated in-situ composites was characterized by the Hirox digital microscope systems which made possible to observe a 3D microscopic images of the composite surface and structural changes after the series of laser irradiation. The study of melted crater ratio has been done on composites to investigate the effect of irradiation on composite surface microstructure. Microstructure of the Ni–TiC composites was also characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). According to experimental results and analysis, it was shown that the observed craters on surfaces were deepened with increasing numbers of laser shot. On the other hand, heterogeneity of samples had influence on the depth of the crater.

Laser plasma sources of soft x-rays an d extreme ultraviolet (EUV) developed in our laboratory for application in various areas of technology and science are presented. The sources are based on a laser-irradiated gas puff target approach. The targets formed by pulsed injection of gas under high-pressure are irradiated with nanosecond laser pulses from Nd:YAG lasers. We use commercial lasers generating pulses with time duration from 1ns to 10ns and energies from 0.5J to 10J at 10Hz repetition rate. The gas puff targets are produced using a double valve system equipped with a special nozzle to form a double-stream gas puff target which secures high conversion efficiency without degradation of the nozzle. The use of a gas puff target instead of a solid target makes generation of laser plasmas emitting soft x-rays and EUV possible without target debris production. The sources are equipped with various optical systems, including grazing incidence axisymmetric ellipsoidal mirrors, a “lobster eye” type grazing incidence multi-foil mirror, and an ellipsoidal mirror with Mo/Si multilayer coating, to collect so ft x-ray and EUV radiation and form the radiation beams. In this paper new applications of these sources in various fields, including soft x-ray and EUV imaging in nanoscale, EUV radiography and tomography, EUV materials processing and modification of polymer surfaces, EUV photoionization of gases, radiobiology and soft x-ray contact microscopy are reviewed. Keywords: laser plasmas, soft x-rays, extreme ultraviolet (EUV), laser plasma soft x-ray and EUV sources, soft x-ray microscopy, EUV radiography and tomography, EUV processing materials, radiobiology, soft x-ray contact microscopy, EUV photo-ionized plasmas

Radiation with shorter illumination wavelength allows for extension of the diffraction limit towards nanometer scale, which is a straightforward way to significantly improve a spatial resolution in photon based microscopes. Soft X-ray (SXR) radiation, from the so called ”water window” spectral range, λ=2.3-4.4 nm, which is particularly suitable for biological imaging due to natural optical contrast, providing much better spatial resolution than one obtained with visible light microscopes. The high contrast is obtained because of selective absorption of radiation by carbon and water, being constituents of the biological samples. We present a desk-top system, capable of resolving 60 nm features in few seconds exposure time. We exploit the advantages of a compact, laser-plasma SXR source, based on a double stream nitrogen gas puff target, developed at the Institute of Optoelectronics, Military University of Technology. The source, emitting quasi-monochromatic, incoherent radiation, in the “water widow” spectral range at λ = 2.88 nm, is coupled with ellipsoidal, grazing incidence condenser and Fresnel zone plate objective. The construction of the microscope with some recent images of test and real samples will be presented and discussed.

The wavelength diffraction limit, described by the Rayleigh criterion, can be overcome if short wavelength radiations are employed, thus it is possible to resolve smaller features by the use of radiation in the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges. In particular way, radiation from the “water window” spectral range, which extends between K-absorption edges of carbon and oxygen (280÷540 eV), could be used in order to obtain high-contrast biological imaging. Laser-plasma double stream gas puff target source is suitable for SXR microscopy in the “water window” spectral range, which recently allowed to develop a system, operating at He-like nitrogen spectral line λ=2.88 nm, which permits to obtain images with half-pitch spatial resolution of ∼ 60 nm, exposure time as low as a few seconds and represents an important alternative for high resolution imaging for biomedical applications, material science and nanotechnology using a very compact laser source. The goal of measurements, presented herein, is to show SXR images of various biological samples, proving high contrast in the “water window” and characterize in more detail such compact microscopy system, based on a laser plasma source with a double stream gas puff target and a Fresnel zone plate (FZP) objective. The influence of various acquisition parameters on the quality of the obtained SXR images, expressed in terms of a signal-to-noise (SNR) will be demonstrated. Moreover, because the measurements are performed on SXR images, similar measurements might be performed as a benchmark in order to characterize different imaging systems as well.

A compact, desktop size, microscope, based on nitrogen double-stream gas puff target soft X-ray source, which emits radiation in water window spectral range at the wavelength of λ = 2.88 nm, is demonstrated. The microscope employs ellipsoidal grazing incidence condenser mirror for sample illumination and Fresnel zone plate objective. The microscope is capable of capturing magnified images of objects with 60 nm spatial resolution and exposure time as low as a few seconds. Details about the source and the microscope as well as a few examples of different applications are presented and discussed.

Design and development of the multi-foil optic (MFO) condenser for a gas puff laser plasma source for EUV lithography is presented. The MFO in general is a soft x-ray optic which consists of two perpendicular sets of very thin reflecting surfaces, where photons are reflected at grazing angles. The aim of the work was to design the condenser working for ~100 eV photons focusing from point to point ~40 cm distant. Initial design and simulations are described and compared to early experiments performed in visible light. The performance of the optic over the initial requirements is discussed. We also briefly discuss several other MFO modifications, including condensers and collimators for laboratory purposes or the wide field x-ray scanning modules for satellite astronomy.

The first results of experiments on direct photo-etching of heated PTFE using a 10 Hz X-ray source based on a laser-irradiated gas puff target are presented. X-ray radiation in the wavelength range from 6 to 20 nm was produced as a result of irradiation of a double-stream gas puff target with Nd:YAG laser pulses of energy 0.8 J and time duration 3 ns. The resulting X-ray pulses with energy of about 100–200 mJ were used to irradiate samples of PTFE to create microstructures by direct photo-etching. Strong enhancement of the photo-etching process was observed for samples heated up to 300 °C.

In this work soft X-ray (SXR) and extreme ultraviolet (EUV) laser-produced plasma (LPP) sources employing Nd:YAG laser systems of different parameters are presented. First of them is a 10-Hz EUV source, based on a double-stream gaspuff target, irradiated with the 3-ns/0.8J laser pulse. In the second one a 10 ns/10 J/10 Hz laser system is employed and the third one utilizes the laser system with the pulse shorten to approximately 1 ns. Using various gases in the gas puff targets it is possible to obtain intense radiation in different wavelength ranges. This way intense continuous radiation in a wide spectral range as well as quasi-monochromatic radiation was produced. To obtain high EUV or SXR fluence the radiation was focused using three types of grazing incidence collectors and a multilayer Mo/Si collector. First of them is a multfoil gold plated collector consisted of two orthogonal stacks of ellipsoidal mirrors forming a double-focusing device. The second one is the ellipsoidal collector being part of the axisymmetrical ellipsoidal surface. Third of the collectors is composed of two aligned axisymmetrical paraboloidal mirrors optimized for focusing of SXR radiation. The last collector is an off-axis ellipsoidal multilayer Mo/Si mirror allowing for efficient focusing of the radiation in the spectral region centered at λ = 13.5 ± 0.5 nm. In this paper spectra of unaltered EUV or SXR radiation produced in different LPP source configurations together with spectra and fluence values of focused radiation are presented. Specific configurations of the sources were assigned to various applications.

The paper presents the results of investigation of the effects of the irradiation parameters on the microstructure and surface in-situ Co-TiC composites obtained by the high temperature solution method (HTS). The obtained ingots were irradiated with Nd:YAG laser pulses (Quantel Brio, 4ns, 70mJ@1.06 m, focused with a lens of the focal length of 10 cm in air conditions. Microstructure of the la ser irradiated in-situ Co–TiC composites was characterized by the Hirox digital microscope systems which made possibl e to observe a 3D microscopic images of the composite surface and structural changes after the se ries of laser irradiation. The study of melted crater ratio has been done on Co–TiC composites to investigate the effect of irradiation on composite surface microstructure. According to experimental results and analysis, it was shown that the ob served craters on surfaces we re deepened with increasing numbers of laser shot. On the other hand, heterogeneity of samples had influence on the depth of the crater.