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Highlights • SnTe as capping layer coatings in the vacuum and extreme ultraviolet spectral regions. • Design and fabrication of VUV quarter wave plates (QWP) based on SnTe/Al bilayer. • Extreme ultraviolet (EUV) improved facility for ellipsometric measurements. • Studying the polarimetric properties of SnTe/Al sample at the wavelength of (121.6 nm). • Angle-dependence phase retarder properties of SnTe/Al also reported in this study. Abstract Vacuum ultraviolet and extreme ultraviolet polarized light plays a significant role in many applications from materials science and solar physics investigations to optical components development. In this paper, we study the optical performances and the quarter wave retarder properties of aluminum coating capped with SnTe/Al thin film. The measurements have been performed by using a reflectometer properly improved for ellipsometric characterizations. The specimen has been fully characterized at hydrogen Lyman–alpha line (121.6 nm) by deriving the reflectance and the ellipsometric parameters, i.e. the ratio r and the phase difference δ. We found that the SnTe/Al bilayer behaves as phase retarder, although the performances differ from the ideal case. In fact, the polarimetric analysis combined with the optical test at different wavelengths allowed to identify carbon contamination on the top layer and a mild oxidation of the aluminum coating that affect the optical throughput. [ABSTRACT FROM AUTHOR]

In synchrotron radiation and electron storage rings, photon-stimulated gas desorption is a major contributor to gas load, leading to vacuum degradation and compromising the stability and quality of the beamline. Therefore, it is imperative to investigate the underlying mechanisms of photon-stimulated gas desorption to enhance the reliability of the experiments. In this paper, a theoretical model for analyzing the process of photon-stimulated desorption is presented, and the equations are solved numerically by considering the evacuation, bulk diffusion, thermal outgassing, adsorption, and desorption of surface gas molecules. The modified model can predict the yield of H 2 gas desorption induced by photon stimulation when synchrotron radiation is directed vertically onto various sample surfaces, utilizing the coupled multi-physics solution. The calculated results are consistent with the experimental measurements obtained from the Shanghai Synchrotron Radiation Facility. The results show that the photodesorption yield is related to the amount of surface-adsorbed molecules, which explains the observed decrease in the photodesorption yield with increasing accumulated photon dose. Furthermore, the study provides a theoretical approach to predicting the pressure evolution of photon-stimulated desorption. • A theoretical model for the analysis of photon-stimulated desorption (PSD) process is presented. • Reveals the mechanism underlying the decrease in the PSD yield with increasing accumulated photon dose. • Methods for predicting the evolution of pressure in the vacuum chamber before and after synchrotron radiation. • Methods for reducing the error between the tested PSD yield and the intrinsic PSD yield. [ABSTRACT FROM AUTHOR]

This paper describes a method for transferring a nanoscale pattern from a cyclic olefin polymer (COP) mold to the surface of UV curable polydimetylsiloxane (PDMS) on a glass substrate. The PDMS is first deposited on the patterned mold by spin-coating and photocuring. Vacuum ultraviolet (VUV) radiation is then used to activate the surface of both the PDMS and the glass substrate before bringing them into contact. Once a bond has been formed, the COP mold is peeled away, leaving the patterned PDMS on the glass substrate. Bonding tests were first carried out to determine the optimum VUV irradiation dose to form a permanent bond. The effectiveness of the proposed method was then demonstrated by transferring a periodic nanoscale pattern. Microscopic examination of the original and transferred patterns revealed that successful reproduction was achieved. A spectroscopic analysis was also performed to clarify the mechanism involved in the bonding process. The results suggested that VUV irradiation caused oxidation of the PDMS surface and the formation of OH groups. When the PDMS and the glass substrate were brought into contact, a dehydration reaction took place which caused the formation of siloxane ( O Si O ) bonds between the two materials. The proposed method offers the advantages of being simple and allowing deformation-free transfer of very fine patterns. It can also be applied to a wide range of nanoscale fabrication tasks. [ABSTRACT FROM AUTHOR]

The present paper is focused on the use of a vacuum ultraviolet absorption spectrometer (VUV) for gas chromatography (GC), within the context of flow modulated comprehensive two-dimensional gas chromatography (FM GC × GC). The features of the VUV detector were evaluated through the analysis of petrochemical and fatty acids samples. Besides responding in a predictable fashion via Beer’s law principles, the detector provides additional spectroscopic information for qualitative analysis. Virtually all chemical species absorb and have unique gas phase absorption features in the 120–240 nm wavelength range monitored. The VUV detector can acquire up to 90 full range absorption spectra per second, allowing its coupling with comprehensive two-dimensional gas chromatography. This recent form of detection can address specific limitations related to mass spectrometry ( e.g., identification of isobaric and isomeric species with very similar mass spectra or labile chemical compounds), and it is also able to deconvolute co-eluting peaks. Moreover, it is possible to exploit a pseudo-absolute quantitation of analytes based on pre-recorded absorption cross-sections for target analytes, without the need for traditional calibration. Using this and the other features of the detector, particular attention was devoted to the suitability of the FM GC × GC-VUV system toward qualitative and quantitative analysis of bio-diesel fuel and different kinds of fatty acids. Satisfactory results were obtained in terms of tailing factor (1.1), asymmetry factor (1.1), and similarity (average value 97%), for the FAMEs mixtures analysis. [ABSTRACT FROM AUTHOR]

The luminescent properties of LSO:Ce (1 mol%) scintillators were characterized systematically under vacuum ultraviolet (VUV)–UV excitation. Under 185 nm VUV excitation, a broad emission band was detected in the wavelength range from 350 nm to 600 nm at different temperatures, which is ascribed to the 5d→4f electron transitions of Ce 3+ . Excitation wavelength and temperature effects on luminescent properties of LSO:Ce ceramic scintillators were investigated in this paper. At 50 K, the emission intensity of Ce1 (Ce 3+ locating in seven-oxygen-coordinated site) was much stronger than that of Ce2 (Ce 3+ locating in six-oxygen-coordinated site), and the total emission intensity excited by 355 nm (Ce1) was higher than that excited by 185 nm (host). The total luminescence intensity increases as the rising temperature in the temperature range of 150–300 K, which is originated from thermal enhancement of transportation of free carriers dominating Ce1 emission. [ABSTRACT FROM AUTHOR]

A high resolution vacuum ultraviolet (HRVUV) beamline based on a 6.65 m off-plane Eagle spectrometer is in operation at the Indus-1 synchrotron radiation source, RRCAT, Indore, India. To facilitate position sensitive detection and fast spectral recording, a new BaFBr:Eu 2+ phosphor based image plate (IP) detection system interchangeable with the existing photomultiplier (PMT) scanning system has been installed on this beamline. VUV photoabsorption studies on Xe, O 2 , N 2 O and SO 2 are carried out to evaluate the performance of the IP detection system. An FWHM of ~0.5 Å is achieved for the Xe atomic line at 1469.6 Å. Reproducibility of spectra is found to be within the experimental resolution. Compared to the PMT scanning system, the IP shows several advantages in terms of sensitivity, recording time and S / N ratio, which are highlighted in the paper. This is the first report of incorporation of an IP detection system in a VUV beamline using synchrotron radiation. Commissioning of the new detection system is expected to greatly enhance the utilization of the HRVUV beamline as a number of spectroscopic experiments which require fast recording times combined with a good signal to noise ratio are now feasible. [ABSTRACT FROM AUTHOR]

• First systematic experimental study of OME oxidation with different chain lengths. • Species pool is dominated by oxygenates and nearly independent of the chain length. • Highest oxygenated intermediate of OME 1-5 combustion is methyl formate. • Reactivity: shift of the intermediate's peak for longer OMEs to lower temperatures. • Significant fractions of ethanol detected using photoionization spectroscopy. This paper presents a systematic study of oxymethylene ethers (OMEs) oxidation in an atmospheric laminar flow reactor setup. Oxymethylene ethers with different number of oxymethylene ether groups (n = 0–5) have been investigated under lean and rich conditions (750–1250 K). The flow reactor is coupled to an electron ionization molecular-beam mass spectrometer (EI-MBMS) with high mass resolution to measure speciation data. Additional isomer-selective speciation analysis was performed using a novel atmospheric laminar flow reactor combined with double-imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy at the vacuum ultraviolet radiation (VUV) beamline of the Swiss Light Source. The results show a dominance of oxygenated intermediates during the combustion of all OMEs in the investigated temperature regime. The observed species pool is thereby nearly independent of the OME's chain length. In particular the presence of significant fractions of ethanol is remarkable and indicates unknown or underestimated reaction pathways to form C–C bonds from OME structures. Formation of combustion intermediates during oxidation of longer OMEs occurs at lower temperatures and correlates with the ignition delay time. No hydrocarbons with more than four carbon atoms are detected. The combination of high mass resolution provided by EI-MBMS detection and isomer-selective analysis by i2PEPICO enables a complete overview of all intermediates. This allows for in-depth discussion and analysis of systematic trends for several intermediate species. [ABSTRACT FROM AUTHOR]

Abstract: Gas phase photoabsorption studies of sulphur dioxide are carried out in the vacuum ultraviolet region using synchrotron radiation. Vibronic Analysis of the system lying in the region 1400–1600Å is reported for the first time. A larger number of spectral features are resolved compared to earlier reports. While most of the observed bands can be arranged into four series with successive band spacing of 500–620cm−1 in agreement with previous work, we observe two additional series with average separation of ∼1750 and ∼1000cm−1. Results of the ab initio calculations suggest that at least three dominant excitations are involved in the system viz. , and . The observed vibrational features are found to be mainly due to excitation of the combination modes (ν 1+ν 2) and (ν 2+ν 3) with some contributions from ν 1 and ν 3. Details of the experiment and analysis are discussed in this paper. [Copyright &y& Elsevier]

Abstract: In this paper, we demonstrate that vacuum ultraviolet (VUV) irradiation was effective to promote the wet etch resistance of perhydro-polysilazane-based inorganic spin-on-glass (PSZ-SOG) film inside the gap. The baking condition of VUV irradiation was chosen at 150°C in 0.2Pa before furnace curing process. Observed the densification characteristics of various trench sizes (aspect ratio (AR)=3.1–0.13), all densification coefficient (Deff ) of the samples with VUV irradiation were larger than 0.90. On the contrary, for the sample without VUV irradiation, a remarkable reduction of Deff values from 0.99 to 0.58 was found while the AR increasing from 0.13 to 3.1. The better densification characteristics of PSZ-SOG films were mainly contributed to the VUV photon. Compared with the reaction mechanisms during VUV irradiation and furnace curing, VUV photon is responsible for triggering the Si–N bond dissociation and accelerating the conversion rate of PSZ. Finally, the new reaction mechanism makes SOG films denser at STI region without additional thermal budget. [Copyright &y& Elsevier]

Abstract: FLASH, the free electron laser at DESY in Hamburg, is the first facility of its kind providing intense, femtosecond radiation pulses in the vacuum ultraviolet and soft X-ray range for user experiments. A broad science program has been started in summer 2005 with applications in atomic and molecular physics, cluster physics, the study of warm dense matter and surface dynamics, and diffraction imaging of small structures and biological samples with nanometer resolution. A selection of first experimental results is highlighted in this paper. [Copyright &y& Elsevier]

Abstract: (Y0.99Bi0.01)BO3 phosphor was prepared and its luminescent properties were investigated using the synchrotron radiation instrument in this paper. Site-selective luminescence of Bi3+ in the YBO3 host was demonstrated by exciting/monitoring with different wavelengths at low temperature in this research. At the same time, the energy transfer between the centers of Bi3+ ions occupying different symmetric sites was observed. The excited energy levels of Bi3+ were identified through assigning the emission and excitation spectra. The paths and mechanism of energy transfer between the centers of Bi3+ occupying different symmetric sites were discussed finally. [Copyright &y& Elsevier]

Abstract: Phosphors play a key role in the performances of display and lighting systems, their quantum efficiency needs to be investigated and improved. That is particularly true in plasma display panels (PDP) because of vacuum ultra violet (VUV) nature of the excitation. It is well established now that a good phosphor for electronic or ultraviolet excitation, is not necessarily a good choice for excitation in VUV. In order to study the behaviour of phosphors, it is necessary to record excitation and absorption spectra and to know precisely the spectral repartition of the excitation source. In the VUV energy range, sodium salicylate is very often used as a reference because of its constant quantum efficiency. In this paper we analyse this quantum efficiency in the near VUV energy range (below 10eV) and its evolution over time. We show that it is far from being constant at these energies and that it decreases in a non-homogeneous manner over time. We also determined the quantum efficiency, in the VUV range, of several NBS standard phosphors and BaMgAl10O17:Eu2+. [Copyright &y& Elsevier]

Abstract: This paper presented a new hybrid process of vacuum ultraviolet (VUV) and TiO2/UV for the decomposition of gaseous formaldehyde (HCHO) at a typical indoor concentration level. The performance was assessed by a preliminary technical and economic analysis. Concentration, flow velocity, relative humidity and light intensity were investigated as process variables. The synergistic or combination effect between VUV and TiO2/UV was attained by comparing the experimental conversions with the calculated ones based on the purifier-in-series efficiency model. The results showed that the proposed hybrid process can be technically feasible and economically attractive for the decomposition of gaseous HCHO. The outstanding merit of the hybrid process is the complementation of advantages of VUV and TiO2/UV. VUV improved the conversion of HCHO markedly on the basis of TiO2/UV. Ozone produced by VUV could be decomposed by TiO2/UV and its concentration was less than the maximum recommended by the WHO at the flow velocity of 0.75m/s or more. There was weak combination effect between VUV and TiO2/UV and the behavior was analyzed in terms of the actions of ozone. The hybrid process was more economical than the TiO2/UV process with a cost reduction of 60% for removing per kg HCHO. [Copyright &y& Elsevier]

Thin films of MgF2 deposited by evaporation is a material widely used for its transparency in the far ultraviolet (FUV) down to ∼115 nm. In this paper the optical properties of ion-beam sputtered (IBS) MgF2 in the FUV are investigated and compared with MgF2 films deposited by evaporation. A slightly higher transparency at the 121.6-nm, H Lyman α line was obtained for IBS MgF2 films compared to films deposited by evaporation, which makes IBS MgF2 a promising protective material for Al reflective coatings. Experimental work on Al films that were protected with a thin evaporated MgF2 film followed by an IBS MgF2 film to produce a protective coating with optimum thickness showed a reflectance at 121.6 nm that was higher by about 3% compared to an Al film protected with an all-evaporated MgF2 film. [Copyright &y& Elsevier]

Photostability of polymers is an important issue since most polymers tend to loose their original properties upon exposure to light, especially to ultraviolet radiation. Polycarbonates are widely used industrial materials because of their excellent properties, which includes transparency, high tensile strength, impact resistance and rigidity. In this paper, we present results on 172 nm photodegradation of polycarbonate (PC) films. PC films of 50 μm thickness were irradiated for up to 20 min using a Xe2* excimer lamp system. Ex situ UV visible spectroscopic investigation of the treated films revealed the appearance of two strong absorption bands at 279 and 317 nm and a third broad band centred around 380 nm whose intensity increased linearly with illumination time. The morphological changes were characterised by atomic force microscopy and resulted in a gradually increasing roughness, being a linear function of irradiation time. The interpretation of the observed chemical degradation is based on attenuated total reflection IR and X-ray photoelectron spectroscopic measurements which show cleavage of the aromatic C–C and carboxylic CO–O bonds together with some nitrogen incorporation into the surface layer of the irradiated films. [Copyright &y& Elsevier]

• Vacuum UV photoabsorption spectrum of trans-1,2-C 2 H 2 Cl 2 for the first time between 5.0 eV and 20.0 eV. • Analysis of electronic and vibrational Rydberg transitions. • Detailed analysis for the first time of the valence transitions. • Interpretation and assignments based on quantum chemical calculations. This paper investigates in detail the vacuum UV photoabsorption spectrum of trans-1,2-C 2 H 2 Cl 2 in the 5–20 eV range using synchrotron radiation. Quantum chemical calculations are applied to the electronic transitions. Particular attention has been paid to the 2a u (π)→2b g (π*) transition included in the broad band observed at 6.30 eV. The Rydberg 2a u (π)→R3s transition is presumably observed at 6.27 eV. Below 6.0 eV the structure(s) are assigned to π→σ* transition(s). The abundantly structured spectrum observed between 7.0 eV and 12.0 eV has been analyzed in terms of vibronic transitions to ns- (δ ¯ =0.844) and nd/4f- (δ ¯ =0.03/0.011) Rydberg states, converging to the 2a u −1 ionization continuum, to two series of np- (δ ¯ = 0.66 and 0.40) states converging to the 5a g −1 continuum, to ns- (δ ¯ =0.983) and nd- (δ ¯ = –0.06) states converging to the 4b u −1 continuum and to two np-type (δ ¯ = 0.51 and 0.26) series converging to the 1b g −1 continuum. These data are complemented by an analysis of the vibrational structure of the individual Rydberg states. Comparisons with previously reported values are provided. Several other spectral features Table S2 (see Supplementary Material) in the 12–20 eV range are tentatively assigned to transitions to Rydberg states converging to higher ionic excited states of trans-1,2-C 2 H 2 Cl 2. Assignments of the vibrational structure of some of these transitions are also proposed. [ABSTRACT FROM AUTHOR]

Highlights: [•] VUV-assisted ultrasonic defluorination of PFOS was firstly demonstrated. [•] VUV had a positive effect on ultrasonic defluorination of PFOS at a certain range. [•] VUV-assisted US system had a lower level of intermediates than US. [ABSTRACT FROM AUTHOR]