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Disinfection eliminates pathogenic microorganisms and ensures a biosafe environment for human beings. The rapid spread of COVID-19 is challenging traditional disinfection methods in terms of reducing harmful side effects and conducting faster processes. Spraying large-scale chemical disinfectants is harmful to individuals and the environment, while UV lamp and light-emitting diode (LED) disinfection still requires a long exposure time due to the low irradiance and highly divergent beam characteristics. Given that a laser maintains a high irradiance over a long distance, we studied the effectiveness of lasers as a new disinfection method, and the results show the capability for ultrafast inactivation of SARS-CoV-2 virus with a 266 nm laser. This work confirms UV lasers as a good candidate for disinfection. [ABSTRACT FROM AUTHOR]

In this work, 193 nm ultraviolet photodissociation-mass spectrometry (UVPD-MS) was applied to investigate supercharging reagent sulfolane in protein sequence and structure characterization. All datasets were collected by using an Orbitrap MS system equipped with an ArF 193 nm EX50 excimer Laser. The 193 nm UV laser has the advantages of high brightness, good stability, and propagate in air, which can directly excite and dissociate the protein backbone within 5 ns (single pulse). Previous reports demonstrated that the partial protein high-order structures and non-covalent interactions could be retained in the UVPD fragments and the site-specific fragmentation yields (FYs) revealed the dynamic protein structure alterations under different conditions. Therefore, the combination of UVPD with nMS provides a new research paradigm for the characterization of protein structure changes. In this work, we further demonstrated 193 nm UVPD was superior to high-energy collision induced dissociation (HCD) in fragmenting and sequencing the non-denatured carbonic anhydrase II (CA) generated in native electrospray ionization (ESI). UVPD could efficiently activate and fragmentate the non-denatured CA with different charge states in just 5 ns, achieving cleavage sequence coverage 79.8% for CA Z10. Then, 0.25% supercharging reagent sulfolane was added into the protein solution and the CA charge distribution was significantly moved to higher charge states under identical native ESI conditions. However, higher-order structures (HOS) and non-covalent interactions could be obtained as the CA charge distribution was still concentrated and significantly different from the spectra features of denatured CA. The UVPD cleavage sequence coverage of the CA was increased to 87.2%, including the regions that were difficult to be dissociated and characterized without sulfolane addition. In addition, the non-covalent of CA and Zn2+ remained stable, indicating that the addition of sulfoxide had little influence on the Zn2+ binding region. The UVPD sequence coverage of CA Z11 was increased by 7.4% after the addition of sulfoxide, but the site FYs were almost not changed, demonstrating the corresponding local structures were nearly not changed. However, the higher charge states introduced by sulfolane also exhibited the risk of inducing specific structure alteration of part of protein regions. In conclusion, it was infered that supercharging reagent is efficient in modulating the charge state distribution of proteins in native ESI-MS characterization and can expand the MS detection mass range. The introduction of supercharging reagent can further improve the UVPD sequence coverage, including the structure-compact regions hard to be fragmented. Although part of the protein HOS and non-covalent interactions seems retained, the influence of higher charge states on protein structures should be considered in dynamic protein structure investigation. [ABSTRACT FROM AUTHOR]

An electron blocking layer (EBL) is often utilized in the p-type region of AlGaN-based deep ultraviolet laser diodes (DUV LDs) to control electron overflow. However, Al-rich semiconductor DUV LD EBLs can be difficult to p-doping and have a highly-complicated structure. Furthermore, the composition of Al in quantum barriers (QBs) of multiple quantum wells (MQWs) affects the performance of AlGaN-based DUV laser diodes. Omitting the EBL and reducing the Al content of the QBs can enhance the optical confinement and optical output power. Observing the performance parameters, such as the optical confinement factor (OCF), emitted power, band diagram, carrier concentration, and stimulated recombination, may be an effective way to monitor these changes. In this paper, using the crosslight software LASTIP, we simulate and compare three DUV LD devices with a nominal wavelength of 267.5 nm. In contrast to the reference DUV LD with a p-type EBL, the proposed EBL-free DUV LD with reduced Al-composition QBs is applied in MQWs; this results in a 21% improvement in the OCF and an increase in the output power. [ABSTRACT FROM AUTHOR]

Nonresonant multiphoton ionization by femtosecond laser pulses can be applied to any molecule virtually, thereby greatly enhancing the scope of Stark decelerated molecules. For comparison, we detect decelerated and trapped ammonia molecules using two different schemes: (i) nonresonant multiphoton ionization using intense femtosecond (fs) pulses in the near infrared, and (ii) resonance-enhanced multiphoton ionization using nanosecond (ns) pulses from a tunable UV laser. The observed number of ions per shot for both schemes is similar. The fs laser detection scheme suffers from an increased background, which can be effectively eliminated by subsequent mass and velocity selection. To determine the detection volume of the ns laser detection scheme, we present measurements in which the decelerated ammonia molecules are bunched to a packet with a longitudinal spread well below ∼100 ÎĽm. It is concluded that the detection volume for the ns laser detection scheme is 1.5â€"2 times larger than that of the fs laser detection scheme. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) composites are widely used in the aerospace field because of their outstanding performance. Laser is an effective method for CFRP composite processing. However, there are corner errors and obvious thermal damage in laser corner cutting, which affect the cutting quality. This article mainly describes the corner error and thermal damage behavior, and the effect of anisotropy of nanosecond UV laser when cutting different corners of CFRP plates. Select six corner angles to perform a full factorial experiment with a right-angled triangle hole cutting under the horizontal and vertical baselines and different laser repetition rates. The results show that there are obvious corner errors and heat affected zone (HAZ) and matrix recession (MR) in laser corner cutting. The corner error always shows that the cut-in error is smaller than the cut-out error (28.06% on average), and the cut-in error and HAZ decrease with the increase of the corner angle, but the difference between the cut-in and the cut-out error increases with the increase of the corner angle. In vertical baseline cutting, the corner error can be reduced to a certain extent, but the HAZ (average 38.42%) is seriously increased, and the thermal damage of linear cutting under a large pulse repetition rate is increased. The large laser repetition rate increases the thermal damage due to the increase of the overlap rate of adjacent pulses but has less effect on the corner error, especially the cut-in error. [ABSTRACT FROM AUTHOR]

This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in nitrogen (N2) to target the NO–N2 rates relevant to high-temperature air, thereby building off the argon (Ar) experiments investigated in Part I. [J. W. Streicher et al., "High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. I. Argon dilution from 2200 to 8700 K," Phys. Fluids 34, 116122 (2022)] Again, two continuous-wave ultraviolet laser diagnostics were used to obtain quantum-state-specific time histories of NO in high-temperature shock-tube experiments, including absorbance (α) in the ground vibrational state of NO, translational/rotational temperature (Ttr), and number density of NO (nNO). The experiments probed mixtures of 2% and 0.4% NO diluted in either pure N2 (NO/N2) or an equal parts N2/Ar mixture (NO/N2/Ar). The NO/N2 experiments spanned initial post-reflected-shock conditions from 1900–7000 K and 0.05–1.14 atm, while the NO/N2/Ar experiments spanned from 1900–8200 K and 0.11–1.52 atm. This work leveraged two vibrational relaxation times from Part I ( τ V T N O − A r and τ V T N O − N O ) and extended measurements to include the vibrational–translational and vibrational–vibrational relaxation times with N2 ( τ V T N O − N 2 and τ V V N O − N 2 ). Similarly, this work leveraged the four rate coefficients from Part I ( k d N O − A r , k d N O − N O , k f N 2 O , and k z N O − O ) and extended measurements to include NO dissociation with N2 ( k d N O − N 2 ). A few studies have directly inferred these rates from experiments, and the current data differ from common model values. In particular, τ V T N O − N 2 differs slightly from the Millikan and White correlation, τ V V N O − N 2 is four times slower than Taylor et al.'s inference, and k d N O − N 2 is four times slower than the Park two-temperature model. The unique experimental measurements and dilution in N2 in this study significantly improve the understanding of the vibrational relaxation and decomposition of NO in high-temperature air. [ABSTRACT FROM AUTHOR]

This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in argon (Ar) to target NO–Ar and NO–NO interactions and to augment the subsequent inference of rates for NO diluted in nitrogen (N2). [J. W. Streicher et al., "High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. II. Nitrogen dilution from 1900 to 8200 K," Phys. Fluids (submitted)]. In both Part I and Part II, two continuous-wave ultraviolet laser diagnostics were used to probe quantum-state-specific time-histories of NO behind reflected shocks in high-temperature shock-tube experiments, enabling inferences of multiple vibrational relaxation times and reaction rate constants for NO decomposition reactions. These diagnostics both probed absorbance (α) in the ground vibrational state of NO but in multiple rotational states utilizing light at 224.8150 and 226.1025 nm. The absorbance was subsequently used to infer quantum-state-specific time-histories for translational/rotational temperature (Ttr) via the absorbance ratio and number density of NO (nNO) via α, Ttr, and the absorbance cross sections (σ). The experiments for Ar dilution probed mixtures of 2% NO/Ar, 1% NO/Ar, and 0.4% NO/Ar for initial post-reflected-shock conditions from 2200–8700 K and 0.12–0.97 atm. Further analysis of the absorbance, temperature, and number density time-histories yielded two vibrational relaxation times ( τ V T N O − A r and τ V T N O − N O ) and four rate coefficients for multiple NO decomposition reactions ( k d N O − A r , k d N O − N O , k f N 2 O , and k z N O − O )—each of which is extended to higher temperatures than any previous study and with reduced scatter and uncertainty. Generally, these rate data are consistent with data from the literature, although τ V T N O − A r and τ V T N O − N O are observed to differ strongly from both the Millikan and White correlation and Park two-temperature model. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D)-printed electronic technology is considered to have great potential as it can be utilized to make electronic products with complex 3D shapes. In this study, based on a 3D printer with single UV laser equipment, we continuously performed photo-polymerization (PP) and selective metal powder sintering to fabricate a conductive pattern. For this, 3D structures were printed at a low energy using a 355 nm DPSS laser with a galvanometer scanner, which are widely used in PP-type 3D printing, and then the selective sintering of metal powders was performed with a high energy. In order to obtain a high-conductivity pattern by laser sintering, a circuit pattern that could actually be operated was fabricated by experimenting with various condition changes from mixing the metal composite resin to the laser process. As a result, it was found that the optimal result was to irradiate a 0.8 W UV laser with a beam spot size of 50 µm to 50 vol% aluminum composite resin. At this time, an optimal conductive pattern with a resistance of 0.33 Ω∙cm−1 was obtained by setting the pulse repetition rate, scan path interval, and scanning speed to 90 kHz, 10 μm, and 50 mm/s, respectively. This suggested process may be of great help in the manufacturing of practical 3D sensors or functional products in the future. [ABSTRACT FROM AUTHOR]

Ferrite composites composed of brittle ferrite ceramic, soft polymers and rubber pose a challenge for low-damage cutting. In this paper, nanosecond UV (Ultra Violet) laser was used to cut the ferrite composite flake with thickness of 0.3 mm. The HAZ (Heat Affected Zone) of nanosecond UV laser cutting composite sheet is studied, and an improved "Scanning-Cooling" strategy for reducing HAZ width is proposed. The results demonstrate that the improved scanning strategy suppresses the expansion of HAZ significantly, and its width is only 147.6 µm (reduced by 7.15 times). Furthermore, parameters are optimized on the basis of the improved strategy, and the narrowest HAZ width of 45.3 µm is obtained under high-laser frequency (120 kHz) and scanning speed (1400 mm/s). Improved scanning strategy and optimized parameters are used to cut and pattern the surface of the electromagnetic shielding patch, with edges of low thermal damage and uniform depth. [ABSTRACT FROM AUTHOR]

To enhance the performance of OLED Micro‐display, we developed the ultra‐high resolution RGB direct patterning of OLED Micro‐display. 3,000ppi FMM by UV Laser process was used and this FMM is manufactured by our unique Laser Patterning process. To improve the luminous efficiency of the OLED Micro‐display device, the RGB dual stack structure was implemented and RGB color filter was applied to improve the color purity. [ABSTRACT FROM AUTHOR]

Short‐wave infrared (SWIR) information is critical for material analysis, imaging sensing, and other fields. To acquire SWIR spectrum with compact devices, strategies for reconstructive microspectrometer have emerged, such as photonic crystal and quantum dot filter. However, the current SWIR microspectrometer needs many filters with insufficient resolution. In this work, the authors develop a SWIR chip‐spectrometer based on Fabry–Perot microcavities array which can be fabricated by using fast and low‐cost UV laser direct‐writing grayscale lithography. The ultra‐compact chip‐spectrometer can work in a very wide range from 900 to 1700 nm with only 20 detector pixels and a reconstruction algorithm. The spectral resolution achieves 2 nm by 50 pixels set and 5 nm by 20 pixels set at SWIR range, which is 3 times higher, with 3.9 times less units number, than for recently reported SWIR quantum dot spectrometers. To the best of our knowledge, this is a minimum high‐resolution SWIR InGaAs detector based chip‐spectrometer which can work in the whole SWIR band with only 20 detector pixels. It has great potential for applications in smart‐phone or other miniature portable spectrometers. [ABSTRACT FROM AUTHOR]

Ultrafast laser processing has recently emerged as a new tool for processing fiber-reinforced polymer (FRP) composites. In the astronautic industry, the modified epoxy resin (named 4211) and the modified cyanate ester resin (known as BS-4) are two of the most widely used polymers for polymer-based composites. To study the removal mechanism and ablation process of different material components during the ultrafast laser processing of FRPs, we isolated the role of the two important polymers from their composites by studying their femtosecond UV laser (260 fs, 343 nm) ablation characteristics for controllable machining and understanding the related mechanisms. Intrinsic properties for the materials' transmission spectrum, the absorption coefficient and the optical bandgap (Eg), were measured, derived, and compared. Key parameters for controllable laser processing, including the ablation threshold (Fth), energy penetration depth (δeff), and absorbed energy density (Eabs) at the ablation threshold, as well as their respective "incubation" effect under multiple pulse excitations, were deduced analytically. The ablation thresholds for the two resins, derived from both the diameter-regression and depth-regression techniques, were compared between resins and between techniques. An optical bandgap of 3.1 eV and 2.8 eV for the 4211 and BS-4 resins, respectively, were obtained. A detectable but insignificant-to-ablation difference in intrinsic properties and ablation characteristics between the two resins was found. A systematic discrepancy, by a factor of 30~50%, between the two techniques for deriving ablation thresholds was shown and discussed. For the 4211 resin ablated by a single UV laser pulse, a Fth of 0.42 J/cm2, a δeff of 219 nm, and an Eabs of 18.4 kJ/cm3 was suggested, and they are 0.45 J/cm2, 183 nm, and 23.2 kJ/cm3, respectively, for the BS-4 resin. The study may shed light on the materials' UV laser processing, further the theoretical modeling of ultrafast laser ablation, and provide a reference for the femtosecond UV laser processing characteristics of FRPs for the future. [ABSTRACT FROM AUTHOR]

A close-packed micro-lens array (MLA) is widely used not only in novel optical systems but also in various engineering fields, such as semiconductors and display devices. In this paper, we present a simple and efficient method for fabricating MLAs on a glass substrate via laser ablation with a single femtosecond laser pulse and chemical wet etching in a hydrofluoric acid solution. The shapes of concave micro-lenses were optimized for laser pulse energy and etching time, and ∼70 000 micro-lenses with 15 µm diameter were formed. The shape of the micro-lens varies significantly with respect to the etching time in accordance with an initial ablated area (or laser energy), which is a key feature in fabricating micro-lenses of several tens of μm. Using the glass MLA as a mold, a polydimethylsiloxane convex-plano lens array was replicated, and the performance of the optical imaging and beam integrator was then examined. [ABSTRACT FROM AUTHOR]

The micromachining of sapphire by laser has dominated research in resent years. This paper provided theoretical and experimental studies of the micromachining of sapphire based on the UV nanosecond laser. The results indicate that the ablation is dominated by the photochemical and photo-thermal through a finite element analysis. The single-pulse ablation threshold of UV nanosecond on sapphire is 15.58 J/cm2, and the ablation threshold gradually decreases and tends to stable finally with the increase of pulse number. Furthermore, the experiment proves that the ablation morphology with a smooth surface and little molten sediment can be realized by optimizing laser processing parameters. [ABSTRACT FROM AUTHOR]

We report the absolute frequency of the v ′ = 1 , N ′ = 2 ← v ″ = 0 , N ″ = 0 vibrational transition in the X 1 Σ + electronic ground state of D 2 . Deuterium molecules in the v ″ = 0 , N ″ = 0 state in a molecular beam are excited to v ′ = 1 , N ′ = 2 using a narrow-linewidth continuous-wave laser stabilised to an optical frequency comb; a strong static electric field in the excitation region induces a transition dipole moment, greatly enhancing the transition strength. Molecules excited to v ′ = 1 , N ′ = 2 are state-selectively ionised using a pulsed ultraviolet laser and mass-selectively detected. Spectra recorded by scanning the infrared laser frequency are fit with a multi-Gaussian model that accounts for the intensities and relative frequencies of all hyperfine components at the static electric field strength used in the measurement. Zero-field absolute transition frequencies were determined from fits of 28 spectra recorded at nine different field strengths. Statistical uncertainty and systematic uncertainties due to the field plate spacing and relative intensities of the hyperfine components comprise the bulk of the overall uncertainty. We determine an absolute S 1 (0) transition frequency of 94,925,100,487(17) kHz after correcting for the photon recoil and second-order Doppler shifts. This value agrees with other recent experimental measurements and a theoretical prediction, but with a lower fractional uncertainty of only 0.2 ppb. [ABSTRACT FROM AUTHOR]

Ultraviolet nonlinear optical (NLO) crystals are the key materials to realize the development of ultraviolet solid-state lasers. At present, NLO crystals mainly rely on borate crystals, but the existing NLO crystals could not meet the applications fully. While it is increasingly difficult to find new NLO crystals, so it is particularly urgent to develop new material systems. From the relationship between borate structures and optical and nonlinear optical properties, it can be known that borates which containing planar conjugated groups have the characteristics of large frequency doubling coefficient, suitable birefringence and short UV cut-off edge. Group with planar conjugated configuration is the core functional unit of borate NLO crystals. The study of expanding planar conjugated groups based on geometric configuration is an important idea for exploring new systems of UV nonlinear optical materials. Based on these, our team proposes to expand the exploration scope of UV NLO crystals by studying CO3, NO3, C(NH2)3 groups with planar triangular conjugated structures and HC3N3O3, H2C4N2O3 groups with planar six-member ring conjuated structures. The research results obtained by our team in the exploration of UV crystals of carbonate, nitrate, guanidine, cyanurate and barbiturate in recent years are mainly introduced in this paper. [ABSTRACT FROM AUTHOR]

Wearable electronics have showed their profound impact in military, sports, medical and other fields, but their large-scale applications are still limited due to high manufacturing costs. As an advanced micro-fabrication process, laser processing technology has the advantages of high speed, high flexibility, strong controllability, environmental protection and non-contact in preparing micro-nano structures of wearable electronics. In this paper, a 355 nm ultraviolet laser was used to pattern the copper foil pasted on the flexible substrate, and the interconnection electrodes and wires were constructed. A processing method of multi-parallel line laser cutting and high-speed laser scanning is proposed to separate and assist in peeling off excess copper foil. The process parameters are optimized. A stretchable 3 × 3 light-emitting diode (LED) array was prepared and its performance was tested. The results showed that the LED array can work normally under the conditions of folding, bending and stretching, and the stretch rate can reach more than 50%. A stretchable temperature measurement circuit that can be attached to a curved surface was further fabricated, which proves the feasibility of this process in the fabrication of small-scale flexible wearable electronic devices. Requiring no wet etching or masking process, the proposed process is an efficient, simple and low-cost method for the fabrication of stretchable circuits. [ABSTRACT FROM AUTHOR]

• Screen-printing Ag paste technology plays an important role in n-TOPCon solar cell. • The energy density threshold of UV pulse laser ablate SiN x were investigated. • The mechanism of Al paste and n+-poly-Si contacts was revealed. • The best efficiency was 22.56% with Al paste (25 wt%-29 wt% silicon). Screen-printing Ag paste on the rear side of the Tunnel Oxide Passivated Contact solar cells (TOPCon) is still the mainstream method to form electrodes. However, the high price of precious metals increases the cost of TOPCon cells. Al is a cheap and high-performance conductor, and its work function is compatible with the rear side of TOPCon cells. In this study, we used a UV pulse laser (355 nm, 10 ps) to ablate the rear side SiN x passivation layer of TOPCon cells and then printed Al paste with different weight percentages of silicon (Si-wt.%) on the phosphorus-doped polycrystalline silicon (n+-poly-Si) layer to reduce the cost. We investigated the damage mechanism of laser on SiO x /n+-poly-Si/SiN x passivation structure and the contact mechanism between Al paste and n+-poly-Si layer. The results show that the V oc of SiO x /n+-poly-Si/SiN x passivation structure reduced about 6–7 mV when the laser energy density was 0.431 J/cm2. We got the best electrical performance of TOPCon cells printed with Al paste (25 wt%-29 wt% silicon). The open-circuit voltage (V oc) and the conversion efficiency (E ff), have reached 663.60 mV and 22.56 % respectively. Although the efficiency was 9.40 % relative lower than that of TOPCon cells printed with Ag paste, but the cost of Al paste only accounted for 10 % of Ag paste. In the future, the highest E ff of TOPCon solar cells printed with Al paste on the rear side are expected to reach the commercial TOPCon based on Ag paste, which applies laser doping selective emitter technology (SE) and bifacial poly-Si passivation structure. [ABSTRACT FROM AUTHOR]

In this study, deep UV resonance Raman spectroscopy (DUV-RRS) was coupled with high performance liquid chromatography (HPLC) to be applied in the field of pharmaceutical analysis. Naproxen, Metformin and Epirubicin were employed as active pharmaceutical ingredients (APIs) covering different areas of the pharmacological spectrum. Raman signals were successfully generated and attributed to the test substances, even in the presence of the dominant solvent bands of the mobile phase. To increase sensitivity, a low-flow method was developed to extend the exposure time of the sample. This approach enabled the use of a deep UV pulse laser with a low average power of 0.5 mW. Compared to previous studies, where energy-intensive argon ion lasers were commonly used, we were able to achieve similar detection limits with our setup. Using affordable lasers with low operating costs may facilitate the transfer of the results of this study into practical applications. [Display omitted] • HPLC-coupled deep UV resonance Raman detector. • Increasing sensitivity using a low-flow method. • Ecologically friendly due to low laser power. [ABSTRACT FROM AUTHOR]

[Display omitted] • Irradiation of crystalline Si and Ge with single 400 nm, 100 fs laser pulses. • fs-resolved optical microscopy over a wide temporal window, up to 15 ns. • Unravel dynamics of free-electron plasma formation, non-thermal melting, ablation. • At high fluences, anomalous transient high-reflectivity state. • Indicative of recoil pressure-induced liquid–liquid phase transition. Femtosecond laser processing of semiconductors has evolved into a mature, high-precision fabrication technique, enabling a wide range of applications. While initially most studies have employed pulses at near infrared wavelengths, the interest in using UV laser pulses is constantly increasing due to the different excitation conditions as a consequence of the much shorter optical penetration depth, leading to an improved resolution. In this context, fundamental studies on the temporal dynamics of phase transformations triggered by such pulses are necessary in order to comprehend and eventually control the complex phase transformation pathways. Here, we report a detailed time-resolved study on the phase transformation dynamics of crystalline silicon and germanium upon irradiation with single 400 nm, 100 fs laser pulses in the moderate and high excitation regime. To this end, we have employed fs-resolved optical microscopy with a probe wavelength of 800 nm to study the reflectivity evolution of the irradiated surface over a temporal window ranging from 100 fs up to 20 ns. At moderate excitation fluence, the data reveals the entire sequence of laser-induced processes, starting from the generation of a free-electron plasma, non-thermal melting, ablation onset and expansion of a semi-transparent ablation layer with sharp interfaces. At excitation with peak fluences more than 30 times the ablation threshold, an anomalous transient high-reflectivity state is observed, which might be indicative of a recoil pressure-induced liquid–liquid phase transition. Moreover, 70 nm-thick amorphous surface layers are formed in both materials after irradiation at moderate fluences. Overall, our results provide relevant information on both, transformation dynamics and final state of both materials for fs-pulse excitation in the near-UV wavelength range. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fast and sensitive multi-elemental mapping of laser-deposited Hastelloy coating using UV-fs-LA-ICP-TOFMS. • Spatial distributions of major, minor and trace elements in the Hastelloy coating, interface and carbon steel substrate. • Detection of elements from external corrosive agents with heterogenous spatial distributions within the Hastelloy coating. • Quantification approach to determine the elemental concentrations in the Hastelloy coated carbon steel. Ultraviolet Femtosecond Laser Ablation-Inductively Coupled Plasma-Time of Flight Mass Spectrometry (UV-fs-LA-ICP-TOFMS) is critically evaluated for fast multi-elemental mapping of Hastelloy coated carbon steel that was immersed in a liquid corrosive environment for two months. The Hastelloy coating, which is a multi-elemental Cr-Fe-Ni-Mo-W matrix, is produced using laser cladding technology. A UV-fs laser is employed to reduce the ablation thermal effects improving the spatial resolution in the elemental analysis of the coating, interface and substrate. Moreover, the TOFMS is equipped with ion beam attenuation grids to expand its linear dynamic range, allowing the determination of major, minor and trace elements. In particular, spatial distribution of major (e.g., Co, Ni, Fe), minor (e.g., Mn, Si) and trace (e.g., Cu, In, Zn) elements from two sequential mapping analysis were determined. Quantification is achieved through Relative Sensitivity Factors calculated using matrix-matched external reference materials and making use of measurements carried out by SEM-EDX to determine the concentration of internal standard elements. Qualitative and quantitative elemental maps highlight diffusion processes at the coating-substrate interface. Moreover, correlated spatial distributions of ion signals from external corrosive elements (e.g., 32S, 138Ba, 202Hg, 205Tl, and 209Bi) were detected in localized regions within the material and on the external surface. [ABSTRACT FROM AUTHOR]

The Modulation Transfer Function (MTF) offers an objective measure to assess the imaging performance of streak cameras. This study aims to enhance the diagnostic precision of streak camera used in laser-driven inertial confinement fusion research. We introduce a novel method for evaluating the MTF of a recently developed large imaging area streak tube. This method integrates the electron optical MTF theory and the production of a reticle plate-type photocathode. Using ultraviolet and femtosecond lasers, we established two calibration platforms for the streak camera in both static and dynamic modes. We measured the radius of the electrons reaching fluorescent screen and obtained MTFs. Our findings reveal that the ultimate spatial resolutions at off-axis distances of 1.2, 4.7, 8.2, and 11.7mm are 28.5, 27.2, 26.4, 24.9 lp/mm (static) and 25.0, 22.8, 23.0, 21.2 lp/mm (dynamic). Notably, we successfully charted the ultimate spatial resolution distributions across the streak camera's full imaging area in both modes. • A novel method for calibrating the MTF of a large imaging area streak tube is reported. • The radius of the electrons reaching fluorescent screen and the static and dynamic MTFs are measured. • The ultimate spatial resolution distributions across the streak camera's full imaging area in both image modes are obtained. [ABSTRACT FROM AUTHOR]

Proper customization in size and shape is essential in implantable bioelectronics for stable bio-signal recording. Over the past decades, many researchers have heavily relied on conventional photolithography processes to fabricate implantable bioelectronics. Therefore, they could not avoid the critical limitation of high cost and complex processing steps to optimize bioelectronic devices for target organs with various sizes and shapes. Here, we propose rapid prototyping using all laser processes to fabricate customized bioelectronics. PEDOT:PSS is selectively irradiated by an ultraviolet (UV) pulse laser to form wet-stable conductive hydrogels that can softly interact with biological tissues (50 μm line width). The encapsulation layer is selectively patterned using the same laser source by UV-curing polymer networks (110 μm line width). For high stretchability (over 100%), mesh structures are made by the selective laser cutting process. Our rapid prototyping strategy minimizes the use of high-cost equipment, using only a single UV laser source to process the electrodes, encapsulation, and substrates that constitute bioelectronics without a photomask, enabling the prototyping stretchable microelectrode array with an area of 1 cm2 less than 10 min. We fabricated an optimized stretchable microelectrode array with low impedances (∼1.1 kΩ at 1 kHz) that can effectively record rat's cardiac signals with various health states. • Rapid prototyping and customization of implantable bioelectronics by all laser fabrication systems. • Water-stable hydrogel electrode patterning by UV laser-induced phase separation of PEDOT:PSS. • Selective patterning of encapsulation layer by UV laser-induced photo-crosslinking and subsequent cutting process. • Highly stretchable and conformal bioelectronics capable of monitoring In vivo epicardial signals in various conditions. [ABSTRACT FROM AUTHOR]

In recent years, Photodynamic therapy (PDT) has shown great potential in clinics to treat cancer. Due to the limited depth range of UV or visible laser light penetration, the eradication of solid tumors using traditional photosensitizer is difficult. Here, we report the development of a new NIR active photosensitizer covalently conjugated to nanoscale metal-organic frameworks (NMOFs) for the eradication of deep-seated tumors. This photosensitizer can generate reactive oxygen species (ROS) in the presence of near-infrared light irradiation (980 nm) for PDT. Therefore, we use a strategy to develop two-photon absorbing carbon dots with a fluorescence quantum yield of 13%. The NMOFs are fabricated in the presence of folic acid, which enables them to target cancer cells that overexpress the folate receptor. NMOFs are used as a nanocarrier for CDs and are employed to achieve targeted PDT. This study is the first to observe that carbon dots embedded in NMOF composite could generate singlet oxygen (1O 2) under the 980 nm laser light irradiation and also specifically target cancer cells. At a concentration of 100 μg/ml, the nanocomposite demonstrated a 73% rate of cell inhibition. The primary results reported here will show great potential in the future to develop multifunctional carbon dots for targeted two-photon PDT in the presence of higher wavelength light irradiation. [Display omitted] • Herein, we designed a novel metal-organic framework and Carbon dots-based nanocomposite for NIR-responsive targeted PDT. • The ability of CDs to produce 1O 2 under NIR light was confirmed by 1O 2 quenchers like DPBF, and DCFH-DA assay. • MIL-FA was employed as a CDs nanocarrier to achieve high CDs loading, which increased 1O 2 production. • Under a 980 nm light source, a desired in vitro cell death was achieved. [ABSTRACT FROM AUTHOR]

• Finite element level - set (FELS) method was used to simulate the CO 2 laser irradiating process of fused silica optics. • High - resolution morphology detection et al. were conducted to investigate the secondary laser damage characteristics of fused silica optics. • The material migration and re deposition in CO 2 repairing process was verified to be factors that induced laser damage. Fused silica optics, as key components in high - power laser systems, are prone to be damaged under short - pulse ultraviolet (UV) laser irradiation. CO 2 laser is usually used to repair the laser damage and extend the service life of optics. However, the anti - laser damage characteristics of repaired substrates sometimes can't meet the expectation. To facilitate better application of CO 2 laser repairing method, this work studied the CO 2 laser irradiating mechanism of fused silica in detail and investigated the damage characteristics of repaired optical surface through experiments. Firstly, finite element level - set (FELS) method is adopted to simulate CO 2 laser irradiating process. The simulation showed that CO 2 laser irradiation would cause molten material migration, vapor material deposition and affect the formation of residual stress. Various tests of morphology, residual stress, and photo - thermal absorption were conducted to study the changes of laser damage characteristics of repaired craters. The experimental results presented that molten materials migration and vapor materials re deposition occurred in CO 2 laser irradiation, which would promote the formation of residual stress, cause stronger laser absorption, or even induce laser damage. Through the experiment, accuracy of simulation was verified further. In this work, the CO 2 laser repairing mechanism of fused silica and laser damage characteristics of repaired optics are clarified through FELS simulation and experiments. Relative results can provide a certain technical support for the performance improvement of repaired fused silica optics. [ABSTRACT FROM AUTHOR]

• Enhanced efficiency of AlGaN-based Deep-UV-LD through composition grading of quantum barriers and EBL. • Utilized PICS3D software for simulation and analysis of optical properties. • Achieved a significant increase in output power (up to 60 mW) and conduction band barrier height (570 meV). • Improved device intensity, gain, and stimulated recombination rate. • Reduced valence band barrier height, threshold voltage, threshold current, and electron current density. • Demonstrated that increase composition grading in AlGaN-based DUV-LD enhances device performance. • Proposed asymmetric composition-graded QB and EBL structures to boost DUV-laser efficiency. • Conducted an in-depth numerical study showing • reduced threshold current, voltage, and carrier leakage. • Highlighted the potential of the proposed laser structure for improving Deep-UV-laser performance. A deep ultraviolet (DUV) laser diode is a compact and efficient semiconductor device that emits laser light in the deep ultraviolet range. Its unique properties make it suitable for a wide range of applications in fields such as manufacturing, research, and healthcare. In this research we propose two Al-graded Electron Blocking Layer (EBL) and quantum barriers (QBs) to improve the performance of AlGaN-based Deep UV-LDs. The electrical properties and optical properties of three structures containing conventional EBL, composition graded increased EBL, and liner graded increased of EBL and QBs were numerically investigated. It was found that the structure-C with linear graded increased EBL and QBs significantly improved the Optical Confinement Factor (OCF) 21%, gain 1600 cm-1, emission power 0.060 W, raised the carrier concentration in the MQWs region, enhanced the stimulated recombination rate and reduced the carrier leakage, of the laser diode (LDs). But at a 100-mA injection current, the threshold current and voltage were reduced to 43 mA and 5.00 V, valance barrier height 270 meV respectively. In compare to the conventional structure, introducing a graded design for both EBL and Quantum Barriers (QBs) with increased aluminum content significantly enhanced the performance of the laser diode (LD). This improvement is essential for advancing Deep Ultraviolet Laser Diodes (DUV-LD) technology. [ABSTRACT FROM AUTHOR]

The use of an excimer benchtop pulsed UV laser as the energy source for the photochemical modification of the surface of diamond films is reported. Boron-doped nanocrystalline diamond (NCD) films were deposited on Si wafers via plasma-enhanced chemical vapour deposition (PECVD). The as-deposited films were characterised by scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). Following characterisation, the surfaces of the films were subjected to a photochemical reaction with 2,2,2-trifluoroethyl undec-10-enoate using two different sources of radiation: a benchtop UV lamp (254 nm) and a KrF excimer pulsed UV laser (248 nm). The photochemically treated films were characterised by contact angle measurements and X-ray photoelectric spectroscopy (XPS) using non-treated films as a control. The use of a pulsed UV laser source was shown to reduce the photochemical reaction time from several hours to a few minutes. [Display omitted] • Successful photochemical functionalisation of a diamond surface using a pulsed UV laser is reported for the first time. • Time required to functionalise diamond surfaces decreases to tens of seconds with the pulsed UV laser. • A mechanism such as thermal activation may be responsible for the establishment of the chemical bounds. [ABSTRACT FROM AUTHOR]

Energy bands modulations in thin films heterostructure has offered exceptional leads towards the development of photosensing material. In this work, nanostructured metal oxides interfacial electrode structure has been employed to fabricate a highly sensitive ultraviolet (UV) sensor with high responsivity and detectivity. A unique, simple and cost-effective electrodeposition approach was adopted for the growth of the film samples. The interfacial structural effect and optical energy band modulations on the photo-electronic structure and UV detector performance of the structure have been examined. The films had fair transmissions of the visible light spectrum with Cu x O dominance in the resulting bilayer structure and a high absorption peak in the ultraviolet (UV) region. The energy band gap redshifted towards the bilayer structure from 3.74 to 2.67 eV. Charge carriers trapping through surface recombination has been found to reduce from the assistance of ohmic contact formation of the heterostructure. The bilayer film-based photodetector demonstrated enhanced performance with photodetectivity (1.6⨯1011 Jones at 0.068 mWcm−2 power density), attributable to the existence of lower recombination state in the structure, according to the UV sensing study. The study showed that tailoring dissimilar metal oxide semiconducting films to the bilayer (Cu x O/NiO) structure can provide excellent UV photodetector performance over single-layer of NiO and Cu x O. [ABSTRACT FROM AUTHOR]

This study presents the first high-temperature measurements of cyclopentene + OH → k 1 Products reaction over 856 – 1258 K and 1.03 – 4.33 bar. The determined rate coefficients of k 1 exhibited Arrhenius temperature dependence with an activation energy ∼ 3.3 k cal mol−1 and negligible pressure dependence. Rate coefficients of OH + cyclopentene are faster than OH + 1-pentene but comparable to OH + 2-pentene, highlighting the significance of allylic C H bonds in these reactions. At 1258 K, our rate coefficient is ∼ 30 % slower than the average room-temperature measurement, indicating the role of OH-addition pathways at low temperatures. Site-specific rate coefficients and branching ratios are determined, with H-abstraction at the allylic C H site accounting for ∼68 % of the reaction and alkylic C H bond contributing ∼22 %. Our measured k 1 may be given as (unit: cm3molecule−1s−1): k 1 = 1.64 × 10 − 10 e (− 1660 T) Cyclopentene decomposition reaction (cyclopentene → k 2 cyclopentadiene + H 2) is studied over 1186–1472 K and 1.17 – 1.38 bar. Time-resolved yields of the product, cyclopentadiene, are monitored using a sensitive UV laser diagnostic near 220 nm. Absorption cross-sections of cyclopentadiene, measured in two separate mixtures, showed weak positive temperature dependence (8.7 – 9.8 × 10−18 cm2molecule−1) over 961 – 1326 K. Our rate coefficients of k 2 exhibited a positive Arrhenius temperature dependence with an activation energy of ∼ 54.7 k cal mol−1. At 1300 K, the decomposition of cyclopentene proceeds 5.5 and 28 times faster than that of cyclopentadiene and cyclopentane, respectively. Our measured k 2 may be expressed as (unit: s−1): k 2 = 2.55 × 10 12 e (− 27 , 527.6 T) The pentagonal structure of cyclopentene influences its H-abstraction and decomposition reactions distinctively. While H-abstraction by OH follows a mechanism akin to cyclohexene and linear alkenes, with comparable rate coefficients at allylic C H bonds, the penta-ring structure significantly impacts the decomposition mechanism. Cyclopentene decomposition predominantly produces cyclopentadiene and H 2 in a ring-conserving manner, differing from the cleavage of allylic-alkylic C C bonds in the decompositions of 1-alkenes and cyclohexene. [Display omitted] [ABSTRACT FROM AUTHOR]

• Combined atmospheric plasma/UV exposure of polyester fabrics activate fibre surfaces. • Pre- and/or post-exposure of fabrics to which non-durable flame retardants have been applied have improved durability to cleansing treatments. • After cleansing, retained levels of flame retardants have been identified by EDX and XPS surface analyses. • The effect of plasma/UV process sequence (pre-exposure and/or post exposure with respect to FR impregnation) influences retained flame retardant levels. • Retained levels are sufficient to modify thermal degradative properties of polyester. Following application of three commercially available, flame retardants (FR) to polyester and exposure to an atmospheric plasma in the presence or absence of simultaneous UV 308 nm excimer laser radiation, the retentions to a 30 min 40 °C water-soak for the mono- and dimeric cyclophosphonate (PE-CONC and PCO 900 respectively) and a 30 min methanol-soak treatment for the resorcinol bis(diphenyl phosphate) (RDP) agents were generally enhanced with respect to unexposed controls. These results suggested that the formation of PET-FR bonding had occurred as a consequence of plasma/UV exposure. The effect of plasma/UV process sequence (pre-exposure and/or post exposure with respect to FR impregnation) as well as plasma gas type, showed that maximum post-soaking FR retentions occurred when both pre- and post-exposure conditions operated. Plasma/UV exposed fabrics both before and after soaking treatments were examined for morphological changes by SEM and surface phosphorus retention by EDX, FTIR-ATR, XPS as well as TGA/DTG/DTA, each of which showed evidence on the surface of changes in surface topography, increased phosphorus levels and modified thermal behaviour. When subjected to vertical fabric strip flammability testing, these changes were insufficient to generate significant changes in the burning rate apart from in post-methanol soaked, RDP-containing fabrics where almost all plasma/UV process sequences reduced specimen burning rates. During all experiments, the presence or absence of the UV laser radiation appeared to have no obvious effect on post-soaking FR retentions, suggesting that its presence is not required since plasma activation alone appears to be the key to improving PET-FR bonding. [ABSTRACT FROM AUTHOR]

Wavelength-dependent measurements of the RNA base uracil, undertaken with nanosecond ultraviolet laser pulses, have previously identified a fragment at m/z = 84 (corresponding to the C3H4N2O+ ion) at excitation wavelengths ≤232 nm. This has been interpreted as a possible signature of a theoretically predicted ultrafast ring-opening occurring on a neutral excited state potential energy surface. To further investigate the dynamics of this mechanism, and also the non-adiabatic dynamics operating more generally in uracil, we have used a newly built ultra-high vacuum spectrometer incorporating a laser-based thermal desorption source to perform time-resolved ion-yield measurements at pump wavelengths of 267 nm, 220 nm, and 200 nm. We also report complementary data obtained for the related species 2-thiouracil following 267 nm excitation. Where direct comparisons can be made (267 nm), our findings are in good agreement with the previously reported measurements conducted on these systems using cold molecular beams, demonstrating that the role of initial internal energy on the excited state dynamics is negligible. Our 220 nm and 200 nm data also represent the first reported ultrafast study of uracil at pump wavelengths <250 nm, revealing extremely rapid (<200 fs) relaxation of the bright S3(1ππ*) state. These measurements do not, however, provide any evidence for the appearance of the m/z = 84 fragment within the first few hundred picoseconds following excitation. This key finding indicates that the detection of this specific species in previous nanosecond work is not directly related to an ultrafast ring-opening process. An alternative excited state process, operating on a more extended time scale, remains an open possibility. [ABSTRACT FROM AUTHOR]

The separation and detection of isomers remains a challenge for many areas of mass spectrometry. This article highlights laser photodissociation and ion mobility strategies that have been recently deployed to meet this challenge with focus on small molecule isomers including protonation isomers, structural isomers, conformation isomers and new studies emerging on chiral isomers. Laser techniques span UV and visible laser photodissociation, time-resolved pump–probe schemes and application of laser hole-burning arrangements to assign isomers within selected ion populations. Also surveyed are applications of ion mobility strategies to separate isomers followed by laser spectroscopic techniques to assign the separated ions. Ultimately, with ongoing refinement in hardware and methods, there are clear pathways forward for laser and mass spectrometry techniques to make decisive breakthroughs in understanding how isomeric details affect biological processes, physiology and disease. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) lasers with dynamic wavelength‐tunability and high monochromaticity are crucial in a multitude of practical applications yet still remarkable challenges. Here, we show wide wavelength‐tuning of single‐mode UV lasing based on lanthanide‐doped upconversion nanoparticles (UCNPs). The rationally designed Yb3+/Er3+/Tm3+/Gd3+/Ce3+ co‐doped multilayer UCNPs, which exhibits a broad gain spectrum with the full width of half maximum of around 57 nm in the UV regime, are developed. More importantly, by taking advantages of a diffraction grating as the tuning component, stable single‐mode emission can be achieved in the UCNPs‐based external‐cavity‐extended Fabry–Pérot laser at room temperature. Specifically, the lasing threshold is around 137 µJ cm–2, which is two orders of magnitude lower than that in the previously reported articles. Precise wavelength‐tuning from 310 to 363 nm can be realized by adjusting the Littrow angle. This achievement highlights a portable alternative to continuously wideband‐tunable UV lasers and opens up new opportunities for constructing compact solid‐state UV photon sources. [ABSTRACT FROM AUTHOR]

There exists an extensive research interest in the performance improvement of AlGaN-based deep-ultraviolet (DUV) laser diodes (LDs). Herein, to reduce the carrier leakage problem of LDs, we propose a convex waveguide (WG) layer for improving the optoelectronic properties. Numerical analyses are carried out to compare the proposed convex WG layer with traditional and stepped WG layers. For LDs with seven different WG layers, parameters used for comparison are P – I and V – I characteristic curves, carrier concentrations, stimulated recombination rates, slope efficiencies, and electro-optical conversion efficiencies. We show that the application of the convex WG layer considerably enhances the carrier confinement ability of LDs and reduces carrier leakage, improving the performance of the LDs. The overall performance of LDs with only a convex lower WG (LWG) layer or a stepped LWG layer is stronger than that of LDs with only a convex upper WG (UWG) layer or a stepped UWG layer. [ABSTRACT FROM AUTHOR]

Extreme ultraviolet laser ablation and ionization time-of-flight mass spectrometry (EUV TOF), using a laser that operates at a wavelength of 46.9 nm (26.4 eV photon energy), is a relatively new analytical technique with many unexplored performance characteristics. In this work, we use the EUV TOF to directly measure the 206Pb/238U and 232Th/238U isotope ratios in different geological materials to investigate if the EUV laser is a good candidate for reducing matrix effects in geological analyses. We use the EUV TOF to analyze synthetic glasses of silicate, basalt, and phosphate as well as mineral samples ranging from iron manganese to zircons and monazites to uraninites and a thorite at a spatial scale of approximately 8 μm and at depths ≤500 nm. The results show that the EUV TOF measures 206Pb/238U ratios that have a systematically low bias in glass, iron manganese, zircon, and monazite matrices. This bias can be calibrated using NIST 610 as a non-matrix matched external calibration sample, resulting in 206Pb/238U ratios that are within analytical uncertainty (±2σ) of the expected values. Unlike 206Pb/238U, the 232Th/238U ratios measured in the glass, zircon, and monazite matrices do not show a systematic bias and are within ±2σ of the expected values from direct measurements. The 206Pb/238U and 232Th/238U ratios measured in the uraninite and thorite samples are not within analytical uncertainty of the expected values. The uncertainty in the uraninite and thorite measurements are likely a result of the high amounts of Pb, Th, and U in these samples relative to the other analyzed samples and their effect on the instrument's performance. Overall, this study shows that the EUV ionization mechanisms for Pb, Th, and U are similar in glass, iron manganese, zircon, and monazite matrices, resulting in inter-element ratios that are within analytical uncertainty. EUV laser ablation and ionization is therefore a good candidate for directly measuring the isotopic content in select geological materials at spatial scales of <10 μm. [ABSTRACT FROM AUTHOR]

Adhesive bonding of CFRP is one major approach to join this class of compound materials with other components, e.g., metals. The necessity to clean CFRP parts after fabrication and generate a bond-ready interface without damaging the implemented fibers demands a gentle and highly reproducible surface treatment. Lasers operating in the UV region are one promising technique for that topic. Yet, the factors influencing the adhesion properties of laser-treated CFRP are not sufficiently understood. The present paper describes the influence of nanosecond-pulsed laser parameters on CFRP treatment effects in context of adhesive bonding properties. A special focus was given on the distribution and avoidance of re-deposition effects by laser parameter selection. Furthermore, the effect of laser-induced fiber exposure was analyzed. Re-deposition and fiber exposure were complementarily discussed with chemical analyses of the surface composition after laser treatment in the context of bond strength studies under Mode I loading. It was found that both effects, i.e., re-deposition on the treated surface and laser-induced fiber exposure by overtreatment, result in lower strength values compared to an "optimized" treatment exhibiting none of the descripted conditions. [ABSTRACT FROM AUTHOR]

The increasing demand for rare earth elements (REE) requires faster analysis techniques for their rapid exploration. Laser-induced breakdown spectroscopy (LIBS) has on-site and real time analysis capability. However, interference and the weaker emission of minor REEs are key challenges for the complex REE emission spectra. Using simulations and experimental results, we presented essential principles for improved line identification in the transient spectra of complicated samples, such as those of REE ores (e.g., monazite). Knowledge of plasma conditions, spectral collection setup, and capability of the spectral system are key parameters to consider for the identification of an emission line in such spectra. Furthermore, emission intensity dependence on laser wavelength was analyzed for major and minor REEs using IR (1064 nm), visible (532 nm) and UV (266 nm) irradiation. A higher plasma temperature was found with the IR laser, while stronger material ablation was observed by UV irradiation. Higher particle density by UV laser ablation was the key factor in the higher signal intensity of the minor elements, and this laser can improve the emission signals for LIBS use as an REE analyzer. [ABSTRACT FROM AUTHOR]

The state-of-the-art CMOS technology has started to adopt three-dimensional (3D) integration approaches, enabling continuous chip density increment and performance improvement, while alleviating difficulties encountered in traditional planar scaling. This new device architecture, in addition to the efforts required for extracting the best material properties, imposes a challenge of reducing the thermal budget of processes to be applied everywhere in CMOS devices, so that conventional processes must be replaced without any compromise to device performance. Ultra-violet laser annealing (UV-LA) is then of prime importance to address such a requirement. First, the strongly limited absorption of UV light into materials allows surface-localized heat source generation. Second, the process timescale typically ranging from nanoseconds (ns) to microseconds (μs) efficiently restricts the heat diffusion in the vertical direction. In a given 3D stack, these specific features allow the actual process temperature to be elevated in the top-tier layer without introducing any drawback in the bottom-tier one. In addition, short-timescale UV-LA may have some advantages in materials engineering, enabling the nonequilibrium control of certain phenomenon such as crystallization, dopant activation, and diffusion. This paper reviews recent progress reported about the application of short-timescale UV-LA to different stages of CMOS integration, highlighting its potential of being a key enabler for next generation 3D-integrated CMOS devices. [ABSTRACT FROM AUTHOR]

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The CO2 methanation is an important component of the "power to gas" strategy, and the Ru‐Al2O3 catalyst is considered to be a state‐of‐the‐art catalyst for this reaction. Conventional Ru‐Al2O3 is prepared by wet impregnation. Due to weak interactions between Ru and the Al2O3, construction of a controllable interface between the metal and the substrate is still challenging. In this work, a UV pulse laser is used to controllably construct ultra‐small Ru nanoparticles on defects‐rich Al2O3‐x‐L in situ grown on Al foil (Ru‐Al2O3‐x‐L) for effective photothermal CO2 methanation. The catkin‐like fluff Al2O3‐x‐L efficiently traps light to ensure the light adsorption of Ru‐Al2O3‐x‐L. The defects in Al2O3‐x‐L efficiently anchors Ru. A Strong‐Metal‐Support‐Interaction (SMSI) effect is constructed between the ultra‐small Ru nanoparticles and the Al2O3‐x‐L. The Ru‐Al2O3‐x‐L exhibits remarkable photothermal catalytic performance (CH4 yield of 12.35 mol gRu−1 h−1) in the closed batch system. Then an innovative flow reactor is established based on the one‐piece Ru‐Al2O3‐x‐L microchannel catalyst. Thanks to local pressure on the edge of the microchannels, the CH4 yield is further enhanced to 14.04 mol gRu−1 h−1. Finally, an outdoor setup demonstrates the feasibility of photothermal CO2 methanation (CH4 yield of 18.00 mmol min−1). This work provides novel perspectives for the construction of multi‐level micro/nanostructures integrated catalysts for photothermal CO2 methanation. [ABSTRACT FROM AUTHOR]

Atmospheric plasma treatment can modify fabric surfaces without affecting their bulk properties. One recently developed, novel variant combines both plasma and UV laser energy sources as a means of energising fibre surfaces. Using this system, the two most commonly used fibres, cotton and polyester, have been studied to assess how respective fabric surfaces were influenced by plasma power dosage, atmosphere composition and the effects of the presence or absence of UV laser (308 nm XeCl) energy. Plasma/UV exposures caused physical and chemical changes on both fabric surfaces, which were characterised using a number of techniques including scanning electron microscopy (SEM), radical scavenging (using 2,2-diphenyl-1-picrylhydrazyl (DPPH)), thermal analysis (TGA/DTG, DSC and DMA), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). Other properties studied included wettability and dye uptake. Intermediate radical formation, influenced by plasma power and presence or absence of UV, was key in determining surface changes, especially in the presence of low concentrations of oxygen or carbon dioxide (20%) mixed with either nitrogen or argon. Increased dyeability with methylene blue indicated the formation of carboxyl groups in both exposed cotton and polyester fabrics. In the case of polyester, thermal analysis suggested increased cross-linking had occurred under all conditions. [ABSTRACT FROM AUTHOR]

In this work, we show the integration of polysilicon‐based passivating contacts in plated bifacial n‐type PERT (passivated emitter and rear totally diffused) solar cells. We show the viability of n‐PERT cells using two‐side passivating contacts with two‐side plated nickel/silver metallization. Compared with commercially available "TOPCon" cells with rear side passivated contacts only, n‐PERT cells with both side passivated contacts should enable the exploitation of the full potential of passivated contacts. We show that both n‐poly and p‐poly were applied and co‐plated successfully on both sides of n‐PERT solar cells. Considering the potential parasitic absorption losses on the front side of the device originating from p‐poly, we applied selective p‐poly by patterning. We compared two patterning methods for front side polysilicon: the masking and etch approach using inkjet printing and a simple and cost‐effective patterning method using UV laser oxidation. A best efficiency of 22.7% has been achieved with these cells so far on large area (244.3 cm2) n‐type Cz, with a potential efficiency above 24%. Some of these co‐plated bifacial cells have been processed into one‐cell laminates using smart wire interconnection (SWCT) technology. These have passed thermal cycling (TC) tests as defined in IEC61215. [ABSTRACT FROM AUTHOR]

Typically, a 355 nm laser is not sufficient for inducing photochemical ablation and leads to photothermal effects such as melting and recasting. Consequently, most previous studies on the irradiation of polyimide (PI) with such lasers have focused on temperature distribution on the surface and variations in the absorption properties of PI depending on the temperature and time. Herein, the authors demonstrate ablation without thermal effects on the surface of PI using a 355 nm pulse nanosecond laser near the threshold fluence. For ablation without thermal effects, the ablated and nonablated areas can be clearly distinguished in the area exposed to the laser. The interface between these areas, that is, the ablation shape, became wider with increasing laser fluence, even when the spot size remained unchanged; also, the shape of the ablated area was related to the laser intensity distribution. Ablation with thermal effects began to appear in the nonablated areas at higher laser fluence. This study shows that PI, which is physically stable and relatively inexpensive, can be used to develop cation exchange membranes, which can be applied to organic flow cells as well as microbial fuel cells. [ABSTRACT FROM AUTHOR]

Single cell RNA sequencing has the potential to elucidate transcriptional programs underlying key cellular phenotypes and behaviors. However, many cell phenotypes are incompatible with indiscriminate single cell sequencing because they are rare, transient, or can only be identified by imaging. Existing methods for isolating cells based on imaging for single cell sequencing are technically challenging, time-consuming, and prone to loss because of the need to physically transport single cells. Here, we developed See-N-Seq, a method to rapidly screen cells in microwell plates in order to isolate RNA from specific single cells without needing to physically extract each cell. Our approach involves encapsulating the cell sample in a micropatterned hydrogel with spatially varying porosity to selectively expose specific cells for targeted RNA extraction. Extracted RNA can then be captured, barcoded, reverse transcribed, amplified, and sequenced at high-depth. We used See-N-Seq to isolate and sequence RNA from cell-cell conjugates forming an immunological synapse between T-cells and antigen presenting cells. In the hours after synapsing, we found time-dependent bifurcation of single cell transcriptomic profiles towards Type 1 and Type 2 helper T-cells lineages. Our results demonstrate how See-N-Seq can be used to associate transcriptomic data with specific functions and behaviors in single cells. A selective sequencing method, termed SeeN-Seq, is presented to link morphological phenotypes to single-cell RNAseq using UV laser patterning of hydrogel porosity. [ABSTRACT FROM AUTHOR]

Cesium lead halide perovskite nanocrystals (NCs) have gained enormous attention as promising light‐emitting and light‐converting materials. Most of their applications require embedding NCs in various matrices, which is a challenging task due to their low stability, especially in the case of red‐emitting CsPbI3 NCs. In this work, a new approach is proposed allowing the formation of red‐emitting perovskite NCs by anion exchange induced directly inside a solid polymer matrix using green‐emitting CsPbBr3 NCs as templates and iodododecane as an iodine source. Moreover, a simple and efficient route to photo‐assisted termination of the anion exchange reaction in the polymer composite after reaching desired optical properties is demonstrated. The findings allow the authors to pattern a thin composite film with an ultrashort UV laser resulting in a selective generation of green‐ and red‐emitting features with a 15 µm resolution. [ABSTRACT FROM AUTHOR]

This Letter describes the development and implementation of an ultraviolet and broadband ultrafast-laser-absorption-imaging (UV-ULAI) diagnostic for one dimensional (1D) imaging of temperature and CN via its B 2 Σ + ← X 2 Σ + absorption bands near 385 nm. The diagnostic was demonstrated by acquiring single-shot measurements of 1D temperature and CN profiles in HMX flames at a repetition rate of 25 Hz. Ultrashort pulses (55 fs) at 800 nm were generated using a Ti:Sapphire oscillator and then amplification and wavelength conversion to the ultraviolet were carried out using an optical parametric amplifier and frequency doubling crystals. The broadband pulses were spectrally resolved using a 1200 l/mm grating and imaged on an EMCCD camera to obtain CN absorbance spectra with a resolution of ≈ 0.065 nm and a bandwidth of ≈ 4 nm (i.e., 260 cm–1). Simulated absorbance spectra of CN were fit to the measured absorbance spectra using non-linear curve fitting to determine the gas properties. The spatial evolution of gas temperature and CN concentration near the burning surface of an HMX flame was measured with a spatial resolution of ≈ 10 μm. 1D profiles of temperature and CN concentration were obtained with a 1-σ spatial precision of 49.3 K and 4 ppm. This work demonstrates the ability of UV-ULAI to acquire high-precision, spatially resolved absorption measurements with unprecedented temporal and spatial resolution. Furthermore, this work lays the foundation for ultraviolet imaging of numerous atomic and molecular species with ultrafast time resolution. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) irradiation-based methods used for viral inactivation have provided an important avenue targeting severe acute respiratory-syndrome coronavirus-2 (SARS-CoV-2) virus. A major problem with state-of-the-art UV inactivation technology is that it is based on UV lamps, which have limited efficiency, require high power, large doses, and long irradiation times. These drawbacks limit the use of UV lamps in air filtering systems and other applications. To address these limitations, herein we report on the fabrication of a device comprising a pulsed nanosecond 266 nm UV laser coupled to an integrating cavity (LIC) composed of a UV reflective material, polytetrafluoroethylene. Previous UV lamp inactivation cavities were based on polished walls with specular reflections, but the diffuse reflective UV ICs were not thoroughly explored for virus inactivation. Our results show that LIC device can inactivate several respiratory viruses including SARS-CoV-2, at ~ 1 ms effective irradiation time, with > 2 orders of magnitude higher efficiency compared to UV lamps. The demonstrated 3 orders of magnitude cavity enhancement relative to direct exposure is crucial for the development of efficient real-time UV air and water purification systems. To the best of our knowledge this is the first demonstration of LIC application for broad viral inactivation with high efficiency. [ABSTRACT FROM AUTHOR]

We report on the development of a novel direct-detection Doppler wind lidar (DD-DWL) within the strong requirements of an aeronautic feed-forward control application for gust load alleviation (GLA). This DD-DWL is based on fringe imaging of the Doppler-shifted backscatter of ultraviolet laser pulses in a field-widened Michelson interferometer (FW-FIMI) using a fast linear photodetector. The double approach of detailed simulation and demonstrator development is validated by field measurements with reference wind sensing instrumentation. These experiments allow us to establish wind determination precision at a high repeat rate, short range resolution and close distance of approximately 0.5 m/s, which is in accordance with the dedicated simulations. These findings lead us to the conclusion that this FW-FIMI-based Doppler wind lidar is a pertinent development meeting the special requirements of this aeronautics application. Second, the developed simulators are well suited (given their validation) to be used in the overall and full analysis as well as the optimization of the lidar-based GLA control scheme. [ABSTRACT FROM AUTHOR]