IR Wavelengths Research Articles

Active tuning of hybrid plasmonics in graphene-covered metallic nanotrench-=SUP=-*-=/SUP=-

Abstract Graphene has recently emerged as a possible platform for integrated optoelectronics and hybrid photonic devices because of its promising electronic and optical characteristics. Here, we propose the active tuning of hybrid plasmonics in intrinsic graphene-based gold rectangle nanotrench by modifying the graphene electron system. We found that the plasmonics response in graphene thicknesses can be unprecedentedly tuned by altering the thickness of thick graphene covering nanotrench geometry. It is explained as the active plasmonics hybridization leading to the tunability of the enhanced e -field localized within the graphene-covered metallic nanotrench. This study can be useful for optoelectronic devices based on hybrid graphene structures at IR wavelengths.

The influence of femtosecond laser produced periodic surface textures on cutting tool friction

The performance thresholds of cutting tool geometries, tool materials and machining systems are often restricted by surface friction from work material engagement and flow across the tool surfaces. This study investigates the influences of geometrically defined surface textures of the tool rake face on forces encountered during two dimensional orthogonal turning. Regular textures featuring highly uniform profiles and inter-surface blending, exhibiting no measurable recast material were produced using a multi-scanning strategy of a femtosecond pulsed laser of near IR wavelength, in specially profiled flat rake faces of cemented carbide cutting tool inserts. A series of complementary tests were carried out on open ended grooved and equivalently sized closed dimpled surface textures of defined area ratios in the presence of a cutting fluid to investigate their effects on cutting and frictional forces when machining a Chromium steel material exhibiting ductile long chip behaviour. Data captured from a purpose designed in-situ lathe based friction test to simulate chip flow during machining, orthogonal turning experiments using a zero degree rake angle setup and laboratory tribometer oscillatory tests using an identical cutting tool and workpiece material tribo-pair and lubrication fluid, highlight the influences of closed and open structured textures on surface lubrication regimes and the consequent friction forces. The results of the study reveal that surface texturing of uncoated cemented carbide tool surfaces can reduce friction when employed with coolant within the tools’ typical operating range. It has also been shown that textures having closed dimple structures produce the lowest friction forces under these conditions and reduced surface wear. The reduction of the measured surface friction produced by the dimpled textures also suggest desirable shifts in the boundary and hydrodynamic lubrication regimes towards the tools’ cutting edge.

Development of a hybrid photoacoustic and optical monitoring system for the study of laser ablation processes upon the removal of encrustation from stonework

In the context of this work, a prototype hybrid photoacoustic (PA) and optical system for the on-line monitoring of laser cleaning procedures is presented. The developed apparatus has enabled the detection of MHz frequency range acoustic waves generated during the laser ablation process. The intrinsically generated PA signals combined with high resolution optical images provide the opportunity to follow the cleaning process accurately and in real time. Technical mock-ups have been used to demonstrate the potential of this novel technique with emphasis given to applications that refer to the restoration of Cultural Heritage (CH) surfaces. Towards this purpose, the real time monitoring of the laser assisted removal of unwanted encrustation from stonework has been achieved using IR and UV wavelengths. This novel approach has allowed for the precise determination of the critical number of laser pulses required for the elimination of the encrustation layer, while highlighting the dominant ablation mechanisms according to the irradiation wavelength. The promising results obtained using the prototype hybrid PA and optical system can open up new perspectives in the monitoring of laser cleaning interventions, promoting an improved restoration outcome.

Narrow‐Band QD‐Enhanced PIN Metal‐Oxide Heterostructure Phototransistor with the Assistance of Printing Processes

AbstractInfrared (IR) phototransistors are important building blocks for the true integration of flat‐panel optoelectronic detectors. Although significant progress is made in obtaining an InGaZnO active layer with IR response, the utilization of a high‐performance detector still has many challenges due to low efficiency, high power consumption, and lagging detection speed. Herein, a positive‐intrinsic‐negative (PIN) heterostructure phototransistor directly modulating the charges' transfer barrier with low power consumption (1 nW), high efficiency (EQE > 700%), a 200 Hz detecting bandwidth, and high detectivity (1 × 1011 cm Hz1/2 W−1) at an IR wavelength (1.5 µm in the high‐frequency circumstance) is demonstrated. These excellent sensing properties of the PIN phototransistor, together with its advantages of low power consumption and versatility, make the use of a heterostructure a powerful strategy for the development of on‐chip optoelectronic detectors.

Optimization of the response time measuring method for liquid crystal variable retarders

Liquid crystal variable retarders (LCVRs) have been extensively used as light polarization modulators for ground-based polarimetric applications. Shortly, LCVRs will be used as polarization state analyzers in two instruments onboard the Solar Orbiter mission of the European Space Agency. Both ground- and space-based polarimeters require LCVR response time values that fulfill the required image acquisition rate of the polarimetric measurements. Therefore, it is necessary to have a reliable method to measure the LCVR optical retardance response times. Response times are usually estimated via optical methods using crossed or parallel polarizers. Nevertheless, these methods measure light intensity transitions to infer the response time instead of directly measuring the changes in the optical retardance. In this work, an experimental setup that uses a Soleil-Babinet variable compensator is proposed. On one hand, this allows one to study the effect of the nonlinear dependence of the light intensity on the optical retardance in the response time determination, which is neglected in most works. On the other hand, the use of the variable compensator allows one to measure the LCVR response times in the highest sensitivity areas of the system that minimizes the uncertainty of the measurement. The six transitions for the Polarimetric and Helioseismic Imager instrument modulation scheme of a representative LCVR have been measured. Based on the results, the optimized conditions to measure response times are found, which can be achieved by using the variable compensator and an IR wavelength (λ = 987.7 nm) as proposed in the experimental setup.

2 mm GISMO Observations of the Galactic Center. II. A Nonthermal Filament in the Radio Arc and Compact Sources*

Abstract We have used the Goddard IRAM 2 Millimeter Observer (GISMO) with the 30 m IRAM telescope to carry out a 2 mm survey of the Galaxy’s central molecular zone. These observations detect thermal emission from cold interstellar medium dust, thermal free–free emission from ionized gas, and nonthermal synchrotron emission from relatively flat-spectrum sources. Archival data sets spanning 3.6 μm–90 cm are used to distinguish different emission mechanisms. After the thermal emission of dust is modeled and subtracted, the remaining 2 mm emission is dominated by free–free emission, with the exception of the brightest nonthermal filament (NTF) that runs through the middle of the bundle of filaments known as the Radio Arc. This is the shortest wavelength at which any NTF has been detected. The GISMO observations clearly trace this NTF over a length of ∼0.°2, with a mean 2 mm spectral index that is steeper than at longer wavelengths. The 2 mm–6 cm (or 20 cm) spectral index steepens from α ≈ −0.2 to −0.7 as a function distance from the Sickle H ii region, suggesting that this region is directly related to the NTF. A number of unresolved (at 21″) 2 mm sources are found nearby. One appears to be thermal dust emission from a molecular cloud that is associated with an enigmatic radio point source whose connection to the Radio Arc is still debated. The morphology and colors at shorter IR wavelengths indicate other 2 mm unresolved sources are likely to be compact H ii regions.

Analysis of Some Parameters and of Possible Types of Shocks in a New Sample of Spitzer/GLIMPSE/EGO Regions of Formation of Massive Stars

A comparative analysis is presented for the physical parameters of gas in various types of molecular clouds, derived from observations and theoretical calculations. Cool, dense fragments of infrared dense clouds (IRDCs)—rare star-forming regions with OH radical emission in the 1720-MHz satellite line, extended green objects (EGOs)— diffuse bipolar outflows discovered by the Spitzer mission at short IR wavelengths, and gas-dust condensations hosting class I and II methanol masers (class I MM and class II MM) are considered. The magnetic fields of these regions are calculated using the empirical criterion of Crutcher (ApJ, 520, 706, 1999) and the equation for numerical modeling of cold turbulent clouds of Ostriker et al. (ApJ, 546, 980, 2001). This modeling is done for three values of the parameter β = (cs/cA)2 relating the sound and Alfven speeds, which describes the effect of the magnetic field: strong (β = 0.01), intermediate (β = 0.1), and weak (β = 1). In 69 EGOs with densities of 104–105.6 cm−3, derived earlier from observations, and with an acceptable temperature range, from Tk ≈ 30 K to Tk ≈ 100 K, the results of the calculations are most consistent with β = 0.1 (|B|= 0.26 mG) and β = 1 (|B|= 0.15 mG) for intermediate and weak magnetic fields, respectively. For class I methanol masers, with gas densities not exceeding 106 cm−3 and a temperature Tk = 80 K, the most plausible value is β = 1 (|B < 0.4 mG), i.e., the expected effect of the magnetic field is weak. Comparison of the sound and Alfven speeds suggests that very faint, low-velocity C-type shocks may exist in these objcts, with the magnetic field exerting little control over the chaotic motions of the material. The shocks are continuous, and do not affect the parameters in the maser condensations. The magnetic intensities found for class I MMs and OH (1720 MHz) regions differ only slightly; according to this parameter, which is related to the density of the medium and the kinetic temperature of the gas, they may be observed in either different or the same gas-dust condensations.

Extra pure tellurium oxide for the growth of high quality paratellurite crystals

Tellurium oxide (IV) single crystals are in demand materials for manufacturing acousto-optical devices optical fibers for IR wavelength range. The initial material for production of active and passive optical materials must have purity better than 99.999 wt% and extremely low concentration of the residual water. The main method of synthesis of TeO2 is oxidation in nitric acid followed by recrystallization from HCl is complicated, also amount of used high purity acids and waste are very high. Besides the residual water content is no less than 10 ppm. In the research we have developed the procedure for the synthesis of high-purity tellurium (IV) oxide without the usage of liquid oxidants. The process of oxidation of elementary Te was carried out in a flowing quartz glass reactor. Air oxygen was used as an oxidizing agent. The oxidation was conducted at 600-670°C during 24 hours. The produced material was a fine crystalline powder of acicular dendritic crystals of bright white color, identified as β-TeO2 due to X-ray. It was as pure as 5N7 due to ICP-MS. The β-TeO2 crystal grown form the synthesized water-free preparation has demonstrated better optical properties towards the crystals grown from commercial TeO2, produced by the «wet» technology.

A Survey of Transparent Conducting Films and Optoelectrical Materials for High Optical Power Applications

The lifetime laser damage performance of a wide range of transparent conductive materials is assessed, including ultrathin metal films, doped metal oxides, doped compound semiconductors, and graphene whose carrier densities span five orders of magnitude from 1018 to 1023 cm−3. Lifetime laser damage thresholds are determined by exposing material surfaces to repeated nanosecond laser pulses at near IR wavelengths (1064 nm). Near threshold fluences, two distinct damage modes, i.e., bulk and discrete, emerge depending on carrier density. These bulk and discrete damage modes are attributed to free carrier‐induced bulk and localized, defect‐driven absorption processes, respectively. For polycrystalline films with free carrier densities greater than ≈1020 cm−3, laser damage thresholds are less than 5 J cm−2. In contrast, bulk absorption is not apparent at thresholds substantially higher than ≈10 J cm−2 in single‐crystal films with free carrier concentrations lower than ≈1019 cm−3. By increasing thickness, films with lower carrier densities can deliver relevant levels of sheet conductance (&lt;200 Ω sq−1) while remaining transparent. These lifetime laser damage threshold measurements offer systematic criteria to select materials aimed at handling high optical powers in optoelectronics devices and emerging plasmonic and metamaterials for lasers.

Terahertz generation and optical characteristics of P-BI.

We present the structural and THz generation characteristics of the molecular salt crystal (E)-2-(4-(dimethylamino)styryl)-1,1,3-trimethyl-1H-benzo[e]indol-3-ium iodide (P-BI) using optical rectification with IR pump wavelengths. P-BI shows a peak-to-peak field ∼6 times greater than inorganic crystal GaP, and a broader THz spectrum. Data were obtained from 0-6THz showing a significant dip in generation at 1.8THz, similar to what has been observed with the THz generation crystal DAST at 1THz. We characterized the power dependence of P-BI at different IR wavelengths, with optimal THz generation at the 1550-nm pump wavelength. To model THz generation as a function of P-BI crystal thickness, we measured the THz complex refractive index and the IR group index; modeling shows that imperfect phase matching leads to spectral narrowing centered at ∼2.5 THz as the crystal thickness is increased. P-BI could provide a useful alternative to inorganic THz generation crystals such a GaP.

Spatio-kinematical model of the collimated molecular outflow in the water-fountain nebula IRAS 16342–3814

Context. Water-fountain nebulae are asymptotic giant branch (AGB) and post-AGB objects that exhibit high-velocity outflows traced by water-maser emission. Their study is important for understanding the interaction between collimated jets and the circumstellar material that leads to the formation of bipolar and/or multi-polar morphologies in evolved stars. Aims. The aim of this paper is to describe the three-dimensional morphology and kinematics of the molecular gas of the water-fountain nebula IRAS 16342−3814. Methods. Data was retrieved from the ALMA archive for analysis using a simple spatio-kinematical model. The software SHAPE was employed to construct a three-dimensional, spatio-kinematical model of the molecular gas in IRAS 16342−3814, and to then reproduce the intensity distribution and position-velocity diagram of the CO emission from the ALMA observations to derive the morphology and velocity field of the gas. Data from CO(J = 1 → 0) supported the physical interpretation of the model. Results. A spatio-kinematical model that includes a high-velocity collimated outflow embedded within material expanding at relatively lower velocity reproduces the images and position-velocity diagrams from the observations. The derived morphology is in good agreement with previous results from IR and water-maser emission observations. The high-velocity collimated outflow exhibits deceleration across its length, while the velocity of the surrounding component increases with distance. The morphology of the emitting region, the velocity field, and the mass of the gas as function of velocity are in excellent agreement with the properties predicted for a molecular outflow driven by a jet. The timescale of the molecular outflow is estimated to be ~70–100 yr. The scalar momentum carried by the outflow is much larger than it can be provided by the radiation of the central star. An oscillating pattern was found associated with the high-velocity collimated outflow. The oscillation period of the pattern is T ≈ 60–90 yr and its opening angle is θop ≈ 2°. Conclusions. The CO (J = 3 → 2) emission in IRAS 16342−3814 is interpreted in terms of a jet-driven molecular outflow expanding along an elongated region. The position-velocity diagram and the mass spectrum reveal a feature due to entrained material that is associated with the driving jet. This feature is not seen in other more evolved objects that exhibit more developed bipolar morphologies. It is likely that the jet in those objects has already disappeared since it is expected to last only for a couple hundred years. This strengthens the idea that water fountain nebulae are undergoing a very short transition during which they develop the collimated outflows that shape the circumstellar envelopes. The oscillating pattern seen in the CO high-velocity outflow is interpreted as due to precession with a relatively small opening angle. The precession period is compatible with the period of the corkscrew pattern seen at IR wavelengths. We propose that the high-velocity molecular outflow traces the underlying primary jet that produces such a pattern.

Design of a Four-Branch Optical Power Splitter Based on Gallium-Nitride Using Rectangular Waveguide Coupling for Telecommunication Links

This paper reports design of a simple four-branch optical power splitter using five parallel rectangular waveguides coupling in a gallium-nitride (GaN) semiconductor/sapphire for telecommunication links. The optimisation was conducted using the 3D FD-BPM method for long wavelength optical communication. The result shows that, at propagation length of 925 μm, the optical power input was successfully split into four uniform output beams, each with 24% of total input power. It is also shown that the relative output power distribution is almost stable through the C-band range. At the operating wavelength of 1.55 μm, the proposed power splitter has an excess loss lower than 0.2 dB. This study demonstrates the opportunity to develop optical interconnections from UV-Visible to near IR wavelengths.

Analysis of vibronic–mode coupling structure in vibrational spectra of fuzeon as a 36 amino acid peptide for hiv therapy beyond the multi–dimensional franck condon integrals approximation

Parameters such as FT¬–IR and Raman vibrational wavelengths and intensities for single crystal Fuzeon are calculated using density functional theory and were compared with empirical results. The investigation about vibrational spectrum of cycle dimers in crystal with carboxyl groups from each molecule of acid was shown that it leads to create Hydrogen bonds for adjacent molecules. The current study aimed to investigate the possibility of simulating the empirical values. Analysis of vibrational spectrum of Fuzeon is performed based on theoretical simulation and FT–IR empirical spectrum and Raman empirical spectrum using density functional theory in levels of HF/6–31G*, HF/6–31++G**, MP2/6–31G, MP2/6–31++G**, BLYP/6–31G, BLYP/6–31++G**, B3LYP/6–31G and B3LYP6–31–HEG**. Vibration modes of methylene, carboxyl acid and phenyl cycle are separately investigated. The obtained values confirm high accuracy and validity of results obtained from calculations.  Molecular Structure of Fuzeon [1–42].Â

On Venus' cloud top chemistry, convective activity and topography: A perspective from HST

Hubble Space Telescope Imaging Spectrograph (HST/STIS) observations were obtained on 3 dates in December 2010 and January 2011 recording the cloud top properties over Aphrodite Terra and a low elevation region downwind of Aphrodite through LSTs extending from 7 to 11 a.m. From these data we trace the cloud top sulfur-oxide chemistry and UV albedo sensitivity to LST, latitude and topography. Above regions co-located in LST and latitude, albedo variations observed at 245 nm parallel those observed at 365 nm-following the pattern expected from Hadley cell circulation. However, darkening of the cloud top albedo at LSTs between 9.5 and 11 h beyond that expected from simple Hadley circulation was also observed. Above the plains the albedo darkening intensified rapidly with LST and was observed at latitudes extending as high as ~30 N; however, above the mountains the darkening was either entirely absent or evident only at 0 N at an intensity 2× lower than that observed over the plains. Because the observed 245 nm albedo LST variations were inconsistent with that expected from multiple scattering of the coincidently retrieved SO2 gas abundance, we conclude that the 245 nm albedo is diagnostic of the vertical and spatial distribution, abundance (and potentially the identity) of Venus' unidentified UV absorber—rather than SO2 gas. The LST albedo trends are best explained by the onset of subsolar convective activity that intensifies with LST expanding vertically from the boundary between the middle and upper clouds to the cloud tops and increasing the detectability of the unknown absorbing species at the cloud tops. The terrain dependence in the observed intensity implies the time at which the expansion reaches the cloud tops is later above the mountains than over the plains. Additionally, at the time of observation, the low-latitude large-scale vertical mixing rates that control the latitudinal gradients of the SO2 and unknown absorber abundances above and within the cloud top region were lower over Aphrodite Terra than the plains, to the extent that photochemical processing destroyed the spatial correlation between those absorbing species. These observations show the power of UV spectroscopy to diagnose the distinct influences of deep (Hadley-cell type) and shallow convective mixing processes on the vertical and horizontal distribution of Venus' unknown absorbing species, and the sensitivity of these processes to LST and topography, relative to the sulfur oxide chemistry. These results are essential for accurate climate modeling—and when compared to recent Venus missions motivate a need for additional follow-on observing campaigns that simultaneously trace key cloud top chemistry and dynamic processes including the LST dependent evolution of planetary scale gravity waves (GWs). With the inevitable aging of the Hubble Telescope, follow-on observations providing temporally coincident traces of the cloud top albedo, sulfur-oxide chemistry and GW features will require a new age of space-based telescopes and Venus orbiting mission with sensitivity to UV, visible and IR wavelengths.

Theoretical Design of an Antireflection Coating for near Infrared Region (800-1500 nm) for glass substrate

The main purpose of this research is to design multilayer filter that can permit the IR wavelength (800-1500 nm), to make the aim of the research comes true, the equations of multilayer system have been derived and developed, and then a program code has been made using FORTRAN language. The films thicknesses of the multilayer could be even quarter wavelength or unlimited The research results illustrated that the best design when the stack number equals to(6).

Investigation of bond oscillation assisted olfactory perception by exciting the molecular chemical bonds using specific IR wavelengths

The principle of olfactory perception had been widely studied. The core of the olfactory theory is based on two different mechanisms or the combination of the two. The first is the shape (weak shape) theory that the olfactory receptor only accepts the molecule with a complementary shape (lock to the key). The second is the vibrational theory that electrons on an odor molecule will be able to tunnel to the olfactory receptors quantum mechanically only when they are assisted by the specific bond vibrational energy of the molecules. Previous studies indicated that human subjects can distinguish the difference between the musk odorant molecules and its deuterated counterparts as evidence to advocate the theory. Scientists who refuted the vibration theory studied “musk-recognizing receptor”, OR5AN1 and discovered that these receptors responded strongly and identically to the deuterated and normal musk odorants in the vitro environmental condition albeit they have different vibrational energies. In this paper, a new method is adopted to investigate the bond vibration-assisted olfactory theory. Narrow bandwidth infrared light sources with specific wavelengths were utilized to illuminate and excite molecular bond oscillation of the odorant molecules. By analyzing the experimental results of 23 human subjects. This study also supported the hypothesis of the “spin residual information theory” that the olfactory perception is aroused by the “residual spin information” of infrared photons left near the odor and receptor molecular bonding sites which absorbed or emitted the infrared photons.

IR irradiation to remove a sub-aerial biofilm from granitic stones using two different laser systems: An Nd: YAG (1064 nm) and an Er:YAG (2940 nm)

A sub-aerial biofilm (SAB) developed on a granite commonly found in the built cultural heritage of the NW Iberian Peninsula was extracted with 2 different IR irradiations using an Nd:YAG laser at 1064 nm and an Er:YAG laser at 2940 nm. The methodology was based on the application of only one scan in order to evaluate the effect of the laser cleaning operated by applying different consecutive laser scanning and the suitability of these lasers as quick tools. The aim of this comparative study was twofold. The first goal was to find the most satisfactory level of extraction by comparing the results obtained by the different laser sources (IR wavelengths). The other aim was to investigate the by-effects induced by both lasers on each granite-forming mineral. Evaluations were made using stereomicroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy with energy-dispersive x-ray spectroscopy. The results were interpreted in terms of SAB extraction and damage induced on the granite. The results showed that the Nd:YAG laser achieved the most successful level of cleaning, because it extracted the most SAB, while causing the least amount of damage to the surfaces. Regardless of the fluence applied, the Er:YAG laser did not completely extract the SAB in only one scan; in addition, a more intense melting of biotite grains was found, producing amorphous fusion crusts and losing the distinction of the cleavage planes.

Tetrodotoxin (TTX) Time–Resolved Absorption and Resonance FT–IR and Raman Biospectroscopy and Density Functional Theory (DFT) Investigation of Vibronic–Mode Coupling Structure in Vibrational Spectra Analysis

Abstract Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish and found in several other aquatic animals (e.g., in blue–ringed octopuses, rough–skinned newts, and moon snails), it is actually produced by certain infecting or symbiotic bacteria like Pseudoalteromonas, Pseudomonas, and Vibrio as well as other species found in animals. Parameters such as FT–IR and Raman vibrational wavelengths and intensities for single crystal Tetrodotoxin (TTX)are calculated using density functional theory and were compared with empirical results. The investigation about vibrational spectrum of cycle dimers in crystal with carboxyl groups from each molecule of acid was shown that it leads to create Hydrogen bounds for adjacent molecules. The current study aimed to investigate the possibility of simulating the empirical values. Analysis of vibrational spectrum of Tetrodotoxin (TTX) is performed based on theoretical simulation and FT–IR empirical spectrum and Raman empirical spectrum using density functional theory in levels of F/6–31G*, HF/6–31++G**, MP2/6–31G, MP2/6–31++G**, BLYP/6–31G, BLYP/6–31++G**, B3LYP/6–31G and B3LYP6–31–HEG**. Vibration modes of methylene, carboxyl acid and phenyl cycle are separately investigated. The obtained values confirm high accuracy and validity of results obtained from calculations. Molecular structure of Tetrodotoxin (TTX) 1–42.

The evolution of brightest cluster galaxies in the nearby Universe – I. Colours and stellar masses from the Sloan Digital Sky Survey and Wide Infrared Survey Explorer

We present a study of the evolution of brightest cluster galaxies (BCGs) in a sample of clusters at $0.05 \leq z<0.35$ from the SDSS and WISE with halo masses in the range $6 \times 10^{13}M_\odot$ (massive groups) - $10^{15.5}M_\odot$ (Coma-like clusters). We analyse optical and infrared colours and stellar masses of BCGs as a function of the mass of their host haloes. We find that BCGs are mostly red and quiescent galaxies and that a minority ($\sim 9$\%) of them are star-forming. We find that the optical $g-r$ colours are consistent with those of red sequence galaxies at the same redshifts; however, we detect the presence of a tail of blue and mostly star-forming BCGs preferentially located in low-mass clusters and groups. Although the blue tail is dominated by star-forming galaxies, we find that star-forming BCGs may also have red $g-r$ colours, indicating dust-enshrouded star formation. The fraction of star-forming BCGs increases with redshift and decreases with cluster mass and BCG stellar mass. We find that cool-core clusters host both star-forming and quiescent BCGs; however, non cool-core clusters are dominated by quiescent BCGs. Star formation appears thus as the result of processes that depend on stellar mass, cluster mass and cooling state of the intra-cluster medium. Our results suggest no significant stellar mass growth at $z<0.35$, supporting the notion that BCGs had accreted most of their mass by $z = 0.35$. Overall we find a low (1\%) AGN fraction detected at IR wavelengths.

Selection of pulsed laser deposition conditions for preparation of perfect thin-film MoSx hydrogen evolution catalysts

The influence of pulsed laser deposition conditions in the geometry “off-axis” on the catalytic properties of MoSx films in the hydrogen evolution reaction is investigated. For the deposition of MoSx films from MoS2 target, pulsed laser radiation from the IR and UV wavelength ranges was used. The angle of incidence of the laser-induced plume on the surface of the substrate in a buffer gas was varied to check the influence of large in-size Mo-enriched particles. The efficiency of the catalyst was estimated from the results of the turnover frequency (TOF) measurement, which made it possible to minimize the influence of the “loading” of the catalyst on its characteristics. The effects of the chemical composition, local structure, and properties of the catalyst–substrate interface on the efficiency of the hydrogen evolution reaction are analysed. The regime of pulsed laser deposition of more effective thin-film MoSx catalysts is determined.