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This work report on the results obtained using the Langmuir probe (LP) measurements in high-power dc magnetron sputtering discharges. Data show clear evidence of two electron components, such as warm and bulk electrons, in the sputtering plasma in a magnetic trap. We have also used optical emission spectroscopy diagnostic method along with LP to investigate the plasma production. Data show that there is a presence of low-frequency oscillations in the 2-3MHz range, which are expected to be generated by high-frequency waves. Analysis also suggests that the warm electrons, in the plasmas, can be formed due to the collisionless Landau damping of the bulk electrons. [ABSTRACT FROM AUTHOR]

Polycyclic heteroaromatic compounds are potentially interesting materials for organic electronic applications. While most of those compounds contain nitrogen or sulfur, oxygen-based structures are much rarer, especially those including annulated pyrane rings. By the utilization of a cascade of Pictet--Spengler reactions and thermally induced ipso-substitutions, a series of peri-benzopyrano-fused nitrogen containing polycyclic aromatic compounds was synthesized and their optoelectronic properties investigated by UV/Vis and emission spectroscopy as well as cyclic voltammetry and DFT-calculations. [ABSTRACT FROM AUTHOR]

Two kinds of biomimetic membranes labelled with chlorophyllaand chlorophyllideawere obtained through hydration of a phosphatidylcholine thin film. These artificial membranes were subjected to UVC irradiation (253.7 nm) for different times and were characterized by spectral methods (Vis absorption and emission spectroscopy, Dynamic Light Scattering). The stability of the samples was checked by zeta potential measurements. A photo-bleaching effect occurred depending on the exposure time. The two types of membranes exhibited different photo-responses. Both bioporphyrins proved to be excellent sensors for detection of changes occurred in artificial lipid bilayers, at molecular level. [ABSTRACT FROM PUBLISHER]

A novel naphthalene benzimidazole (NBI)-based chemosensor ( D2 ) was developed for fluoride ion (F − ) detection. The absorption spectrum of D2 changed dramatically from yellow to blue in the visible region accompanied with a 225 nm red shift of its absorption maximum upon the addition of F − in DMSO. D2 also exhibited a fluorescence turn-off response towards the fluoride ion. The emission intensity of D2 decreased drastically along the increasing F − concentration and the detection limit for F − was as low as 3.2 × 10 − 9 mol/L. 1 H NMR and HRMS-ESI results indicated that the formation of NBI-O − through the desilylation reaction of F − with NBI-OSi was responsible for the spectral changes. Overall, this kind of NBI-type molecules represent a new type chemosensor for the spectral detection of fluoride ion in solution. [ABSTRACT FROM AUTHOR]

Valence and spin states of Fe were investigated in a glass of almandine (Fe3Al2Si3O12) composition to 91 GPa by X-ray emission spectroscopy and energy- and time-domain synchrotron Mössbauer spectroscopy in the diamond-anvil cell. Changes in optical properties, total spin moment and Mössbauer parameters all occur predominantly between 1 bar and ~30 GPa. Over this pressure range, the glass changes from translucent brown to opaque and black. The total spin moment of the glass derived from X-ray emission spectroscopy decreases by ~20%. The complementary Mössbauer spectroscopy approaches reveal consistent changes in sites corresponding to 80–90% Fe2+ and 10–20% Fe3+. The high-spin Fe2+ doublet exhibits a continuous decrease in isomer shift and increase in line width and asymmetry. A high-spin Fe3+ doublet with quadrupole splitting of ~1.2 mm/s is replaced by a doublet with quadrupole splitting of ~1.9 mm/s, a value higher than all previous measurements of high-spin Fe3+ and consistent with low-spin Fe3+. These observations suggest that Fe3+ in the glass undergoes a continual transition from a high-spin to a low-spin state between 1 bar and ~30 GPa. Almandine glass is not expected to undergo any abrupt transitions in electronic state at deep mantle pressures. [ABSTRACT FROM AUTHOR]

In this study, hydrogen production from water splitting in N using an atmospheric pressure rotating gliding arc plasma was investigated. The effect of input HO concentration and total flow rate on the performance of the plasma water splitting process (e.g., H and O yield, H production rate, and energy yield of H) was investigated. N showed a pronouncedly facilitating effect on the HO splitting and H production process due to the reactions of the excited N species [e.g., electronically excited metastable N(A)] with the HO molecules. The maximum H production rate reached up to 41.3 μmols, which is much higher than that of other typical non-thermal plasmas (e.g., ~0.2 μmols for a dielectric barrier discharge). Optical emission diagnostics has shown that in addition to the NO, N, and N that were observed in the pure N spectra, strong OH and NH emission lines also appeared in the HO/N spectra. OH radical is considered as a key intermediate species that could contribute to the formation of H, O, and HO. The increase of the HO concentration could lead to a continuous enhancement of the OH intensity. The rotational temperature of N dropped drastically from 2875 ± 125 to 1725 ± 25 K with the addition of 1 % (mol/mol) HO into the N plasma. [ABSTRACT FROM AUTHOR]

The slurry nebulization ICP-AES method for simultaneous determination of selected elements in dolomite and magnesia was proposed. Based on the investigation results the optimal conditions for this analysis were as follows: particle size < 40 μm, the nitric acid concentration 10%, the RF power 1.0 kW, aqueous solutions (no dispersing agents) and mixing on magnetic stirrer, during the sample introduction into plasma, as homogenization method. The certified reference materials Dolomite CRM 782-1 and High Purity Magnesia BCS-CRM 389/1 were analyzed. Student's t -test proved that there were no statistically significant differences between determined values and the certified ones. This proves that the slurry sample introduction into plasma in ICP-AES technique can be applied for simultaneous determination of elements in dolomite and magnesia. [ABSTRACT FROM AUTHOR]

The minimum laser fluence needed for plasma ignition on a sample during single-shot femtosecond laser ablation has been determined for a set of metals and alloys. Threshold fluence values ranged between 4 and 9 J cm−2 for ablation craters with a diameter of 40 μm. The craters exhibited similar size and shape regardless of the sample type, energy range (for energies per pulse ＜400 μJ) and accumulated energy dosage (＜500 laser shots on the same sample position). The results obtained for the metals (Pb, Ag, Zn, Sn, Cr, Cu, W, Ni and Fe) show a clear trend of the fluence threshold with the work function, evidencing the importance of the surface electron excitation in femtosecond laser–matter interactions. Experiments with the alloyed samples reveal that fluence thresholds for femtosecond plasma ignition are matrix independent. [ABSTRACT FROM AUTHOR]

For laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) imaging experiments – as well as other techniques used for elemental or molecular mapping – the accordance of the measured distribution with the actual distribution is of utmost importance to guarantee reliability of the obtained images. In most experiments reported in the past, the experimental conditions have been chosen so that washout effects and signal carry-over are minimized by scanning the sample surface very slowly. Therefore, measurement times become very long and decently resolved images will require acquisition times of several hours up to more than one day. To increase the application range of LA-ICP-MS for imaging it is important to decrease the measurement times, which is best accomplished by increasing the scanning rates. However, depending on the instrumentation, this can lead to blurring and compromised image quality. In this work, we present a metric to compare the measured elemental distribution with their actual distribution based on a sample with visually distinguishable features. This approach allows quantitative determination of the image quality and enables comparison of multiple measurement conditions. This information can be used for method optimization, to get a reasonable tradeoff between image quality and measurement time. [ABSTRACT FROM AUTHOR]

In this paper, we present a new method for detecting in-plane displacements in microelectromechanical systems (MEMS) with an unprecedented sub-ångström accuracy. We use a curve-fitting method that is commonly employed in spectroscopy to find peak positions in a spectrum. We fit a function to the intensity profile of the image of a silicon beam that was captured with a CCD camera on an optical microscope. The position resolution depends on the amount of pixel noise and on how the moving feature is spread across the detector pixels. The resolution is usually limited by photon shot noise, which can be controlled and lowered in several ways. To demonstrate the technique we measure the adhesion snap-off of two silicon surfaces. We assess the accuracy of the technique using two different silicon MEMS devices and an experimental ultrananocrystalline diamond device. The lowest position noise that we report is obtained by summing 1 577 image lines and is as low as 60 pm root mean square. [2014-0040] [ABSTRACT FROM AUTHOR]

Extreme ultraviolet spectra of highly charged gold were produced with an electron beam ion trap at the University of Electro-Communications, Tokyo. The X-ray spectra (3240–3360 eV) of Au with well-defined maximum charge states ranging from Cu- to Se-like ions were recorded. Guided by configuration interaction calculations, the strongest 3d–5ftransitions have been well defined. [ABSTRACT FROM PUBLISHER]

In this work, different methods employed for the analysis of emission spectra are presented. The proposal is to calculate the excitation temperature (Texc), electronic temperature (Te) and electron density (ne) for several plasma techniques used in the growth of thin films. Some of these techniques include magnetron sputtering and arc discharges. Initially, some fundamental physical principles that support the Optical Emission Spectroscopy (OES) technique are described; then, some rules to consider during the spectral analysis to avoid ambiguities are listed. Finally, some of the more frequently used spectroscopic methods for determining the physical properties of plasma are described. [ABSTRACT FROM AUTHOR]

The emission colors of transparent suspensions of SrMoO4 :Eu3+,Tb3+ nanophosphors in hexane could be finely tuned for use in multicolor transparent displays. The emission color in the green-red spectral region was tuned by changing the concentrations of the Eu3+ and Tb3+ activator ions. SrMoO4 :Eu3+,Tb3+ nanophosphors with diameters of 5 nm were synthesized via solvothermal reactions in a hexane-water bilayer system consisting of Sr-oleate, Eu-oleate, and Tb-oleate complexes in hexane and an aqueous ( NH4 )6 Mo7O24 solution. A simple phase-transfer method was used to prepare the Sr-oleate, Eu-oleate, and Tb-oleate complexes in hexane from aqueous Sr( NO3 )2, Eu( NO3 )3, and Tb( NO3 )3 solutions with the assistance of sodium oleate, oleic acid, and oleylamine. [ABSTRACT FROM AUTHOR]

In comparison with other biological detection technologies, fluorescence bioimaging technology has become a powerful supporting tool for intracellular detection, and can provide attractive facilities for investigating physiological and pathological processes of interest with high spatial and temporal resolution, less invasiveness, and a rapid response. Due to the versatile roles of hydrogen sulfide (H2S) in cellular signal transduction and intracellular redox status regulation, fluorescent probes for the detection of this third signalling gasotransmitter have rapidly increased in number in recent years. These probes can offer powerful means to investigate the physiological actions of H2S in its native environments without disturbing its endogenous distribution. In this feature article, we address the synthesis and design strategies for the development of fluorescent probes for H2S based on the reaction type between H2S and the probes. Moreover, we also highlight fluorescent probes for other reactive sulfur species, such as sulfane sulfurs and SO2 derivatives. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) hot spots occur when molecules are positioned near regions of strongly enhanced electromagnetic fields on the surface of nano-featured plasmonic substrates. The emission from the molecule is coupled out into the far field by the plasmon modes of the substrate, but due to the diffraction-limit of light, the properties of this coupled molecule-plasmon emitter cannot be resolved using typical far-field optical microscopy techniques. However, by fitting the emission to a model function such as 2-dimensional Gaussian, the relative position of the emitter can be determined with precision better than 5 nm in a process known as super-resolution imaging. This tutorial review describes the basic principles of super-resolution imaging of SERS hot spots using single molecules to probe local electromagnetic field enhancements. New advances using dipole-based fitting functions and spectrally- and spatially-resolved measurements are described, providing new insight into SERS hot spots and the important roles of both the molecule and the substrate in defining their properties. [ABSTRACT FROM AUTHOR]

Vertically aligned graphene was grown by plasma-enhanced chemical vapor deposition using methane feedstock. Optical emission spectroscopy (OES) was used to monitor the plasma species, and Raman spectroscopy was used for characterizing the properties of as-grown vertically aligned graphene. OES-derived information on plasma species, such as C, C2, CH, and H, are correlated with the properties of the vertically aligned graphene. Graphene grown at 250 W and 15 sccm exhibited the lowest amount of defects. Although OES peak intensities occurred at the highest power and lowest flow conditions, the OES peak ratios of plasma species had a greater dependence on flow rate and exhibited a saddle point in the atomic C/H ratio corresponding to optimal growth involving the lowest amount of overall defects. Plasma diagnostics provides a valuable approach to optimize growth characteristics and material properties. [ABSTRACT FROM AUTHOR]

The interactions between Sm3+ and oxygen vacancies in CeO2 are probed by the use of tuneable laser excited time-resolved photoluminescence and Raman spectroscopies. It is found that Sm3+ (with doping concentrations of 0.1, 0.3, 1 and 5 wt%) substitutes largely for Ce4+ in sites with cubic symmetry and the corresponding emission is sensitized via the Ce4+-O2- charge-transfer band of CeO2. It is established from the photoluminescence spectra measured at long delay after the laser pulse that the local environment around cubic Sm3+ centres is not changed with concentration and ceria size. In addition to cubic symmetry Sm3+ centres, low-symmetry Sm3+ centres tentatively assigned to the Sm3+-oxygen vacancy associates of nearest-neighbour type are also observed. Their emission is preferentially excited via the weak f-f absorption transitions of Sm3+. A relatively strong concentration-induced quenching of Sm3+ emission was inferred from the decrease in the average emission lifetimes from 2.1 ms (0.1 wt%) to 0.87 ms (5 wt%). The local environments of Sm3+ and Eu3+ in CeO2 are also compared on the basis of their emission spectra and decays. [ABSTRACT FROM AUTHOR]

The immobilization of technetium-99 (99Tc) in a suitable host matrix has proven to be a challenging task for researchers in the nuclear waste community around the world. In this context, the present work reports on the solubility and retention of rhenium, a nonradioactive surrogate for 99Tc, in a sodium borosilicate glass. Glasses containing target Re concentrations from 0 to 10?000 ppm [by mass, added as KReO4 (Re7+)] were synthesized in vacuum-sealed quartz ampules to minimize the loss of Re from volatilization during melting at 1000 °C. The rhenium was found as Re7+ in all of the glasses as observed by X-ray absorption near-edge structure. The solubility of Re in borosilicate glasses was determined to be ∼3000 ppm (by mass) using inductively coupled plasma optical emission spectroscopy. At higher rhenium concentrations, additional rhenium was retained in the glasses as crystalline inclusions of alkali perrhenates detected with X-ray diffraction. Since 99Tc concentrations in a glass waste form are predicted to be <10 ppm (by mass), these Re results implied that the solubility should not be a limiting factor in processing radioactive wastes, assuming Tc as Tc7+ and similarities between Re7+ and Tc7+ behavior in this glass system. [ABSTRACT FROM AUTHOR]

The present research demonstrates a novel microhollow cathode discharge based on the dielectric barrier discharge principle (DB-MHCD) for application as an analytical microplasma gas detector. The plasma is formed inside a microfabricated multilayer structure and is mainly confined in a bore with a diameter of 100–250 μm. The DB-MHCD operates with alternating rectangular voltages of 1–2 kVpp and a frequency of 50 kHz. The insulation of the electrodes by the dielectric layer prevents deterioration of the electrodes and eliminates contamination of the gaseous analyte with electrode material. This enables long-term operation of the DB-MHCD device over several days. The analytical performance of the DB-MHCD is demonstrated with halogenated hydrocarbons leading to an excellent detection limit of 27 ppb for gaseous Cl in He. [ABSTRACT FROM AUTHOR]