Measurements Of Optical Properties Research Articles

Optical characterization of liquid phantoms in 500–1000 nm using an improved single integrating sphere system

This paper reports on optical characterization (absorption coefficient μa and reduced scattering coefficient μs′) of liquid phantoms in the wavelength range of 500–1000 nm using an improved single integrating sphere system. 54 liquid optical phantoms (18 pure absorption, pure scattering and mixed samples each) with known optical properties were first prepared. The overall performance of a laboratory-established single integrating sphere system was then evaluated, and the results indicated that the system has perfect stability, repeatability, and accuracy in optical property measurement. After that, effect of cuvette size (i.e., optical path and wall thickness) on optical property measurement was investigated. The experimental results showed that the discrepancies of the measured optical properties for the pure absorption and scattering phantoms held by different cuvettes with varying optical paths and wall thicknesses were within 8.76 %. Finally, the effect of different concentrations of absorber and scatterer on optical property determination of mixed liquid phantoms were explored. It was found the measured optical properties of the mixed liquid phantoms had a considerable difference from those of the pure absorption and pure scattering phantoms. We guessed that the addition of the absorber (scatterer) would dilute the concentration level of scatterer (absorber), and also brought about interaction between the two particles, and thus resulting in an offset for the measured optical properties. Future work needs to test our conjecture from the micro level, like monitoring the dynamic change of the absorption and scattering particle distribution and interaction, when optically characterizing the mixed liquid phantoms.

Experimental and numerical investigation of magneto-plasma optical properties toward measurements of opacity relevant for compact binary objects

Electromagnetic transients known as kilonovae (KN), are among the photonic messengers released in the post-merger phase of compact binary objects, for example, binary neutron stars, and they have been recently observed as the electromagnetic counterpart of related gravitational-wave (GW) events. Detection of the KN signal plays a fundamental role in the multi-messenger astronomy entering in a sophisticated GW-detecting network. The KN light curve also delivers precious information on the composition and dynamics of the neutron-rich post-merger plasma ejecta (relying on r-process nucleosynthesis yields). In this sense, studying KN becomes of great relevance for nuclear astrophysics. Because of the highly heterogeneous composition, plasma opacity has a great impact both on radiative transport and spectroscopic observation of KN. Theoretical models attempting in encoding the opacity of this system often fail, due to the complexity of blending plethora of both light- and heavy-r nuclei transition lines, requesting for more complete atomic database. Trapped magneto-plasmas conceived in PANDORA could answer to these requests, allowing experimental in-laboratory measurements of optical properties and opacities, at plasma electron densities and temperatures resembling early-stage plasma ejecta’s conditions, contributing to shed light on r-process metallic species abundance at the blue-KN diffusion time. A numerical study has been recently performed, supporting the choice of first physics cases to be investigated and the design of the experimental setup. In this article, we report on the feasibility of metallic plasmas on the basis of the results from the systematic numerical survey on optical spectra computed under non-local thermodynamic equilibrium (NLTE) for several light-r nuclei. Results show the great impact of the NLTE regime of laboratory magneto-plasmas on the gray opacity contribution contrasted with those under the astrophysical LTE assumption. A first experimental attempt of reproducing ejecta plasma conditions has been performed on the operative Flexible Plasma Trap (FPT) at the INFN-LNS and here presented, together with first plasma characterization of density and temperature, via non-invasive optical emission spectroscopy (OES). The measured plasma parameters have supported numerical simulations to explore optical properties of NLTE gaseous and metallic plasmas, in view of the near-future plasma opacity measurements through spectroscopic techniques. The novel work so far performed on these under-dense and low-temperature magneto-plasmas, opens the route for the first-time to future in-laboratory plasma opacity measurements of metallic plasma species relevant for KN light curve studies.

Measurement and Modeling of the Optical Properties of Adipose Tissue in the Terahertz Range: Aspects of Disease Diagnosis.

In this paper, the measurement and modeling of optical properties in the terahertz (THz) range of adipose tissue and its components with temperature changes were performed. Spectral measurements were made in the frequency range 0.25–1 THz. The structural models of main triglycerides of fatty acids are constructed using the B3LYP/6-31G(d) method and the Gaussian03, Revision B.03 program. The optical density (OD) of adipose tissue samples decreases as temperature increases, which can be associated mostly with the dehydration of the sample. Some inclusion of THz wave scattering suppression into the OD decrease can also be expected due to refractive index matching provided by free fatty acids released from adipocytes at thermally induced cell lipolysis. It was shown that the difference between the THz absorption spectra of water and fat makes it possible to estimate the water content in adipose tissue. The proposed model was verified on the basis of molecular modeling and a comparison with experimental data for terahertz spectra of adipose tissue during its heating. Knowing the exact percentage of free and bound water in adipose tissue can help diagnose and monitor diseases, such as diabetes, obesity, and cancer.

Observation of room temperature d0 ferromagnetism, bandgap narrowing, zero dielectric loss, dielectric enhancement in highly transparent p-type Na-doped rutile TiO2 compounds for spintronics applications

The Na-doped TiO2 compounds, i.e Ti1−xNaxO20≤x≤0.12 were synthesized via the solid-state synthesis method. The formation of single rutile phase with tetragonal structure was identified through the structural study by recording the XRD patterns. The analyses of the XRD patterns further indicate that Na+ ions are likely being substituted at the interstitial site of Ti4+ ions. The microstructural study using SEM revealed the homogeneous morphology of all compounds, with the particle size in the range of 1–2 μm. The room temperature magnetization versus field measurement reveals a ferromagnetic behavior for all Na-doped compounds with coercivity values ranging from 100 to 930 Oe. The saturation magnetization was observed to be maximum for Ti0.97Na0.03O2 compound but thereafter it decreases. According to optical property measurements, the bandgap reduces from 2.94 to 2.71 eV as the concentration of Na doping increases. The maximum transmittance value 91% was noted for Ti0.97Na0.03O2 compound. The Hall effect measurements indicate that the carrier concentration of all Na-doped TiO2 ranged from 1.077×1015 to 7.579×1015/cm3, and it grew monotonically with the increase of Na-doping concentration. The value of the ac conductivity and dielectric constant were observed to enhance with increasing Na-doping concentration; indicating that transport occurs via hopping of the charge carrier. Further, the dielectric properties observation reveals lossless nature in the produced sample, which suggests that this material could be employed in high-frequency optoelectronic devices.

Measurements from inside a Thunderstorm Driven by Wildfire: The 2019 FIREX-AQ Field Experiment

Abstract The 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field experiment obtained a diverse set of in situ and remotely sensed measurements before and during a pyrocumulonimbus (pyroCb) event over the Williams Flats fire in Washington State. This unique dataset confirms that pyroCb activity is an efficient vertical smoke transport pathway into the upper troposphere and lower stratosphere (UTLS). The magnitude of smoke plumes observed in the UTLS has increased significantly in recent years, following unprecedented wildfire and pyroCb activity observed worldwide. The FIREX-AQ pyroCb dataset is therefore extremely relevant to a broad community, providing the first measurements of fresh smoke exhaust in the upper troposphere, including from within active pyroCb cloud tops. High-resolution remote sensing reveals that three plume cores linked to localized fire fronts, burning primarily in dense forest fuels, contributed to four total pyroCb “pulses.” Rapid changes in fire geometry and spatial extent dramatically influenced the magnitude, behavior, and duration of pyroCb activity. Cloud probe measurements and weather radar identify the presence of large ice particles within the pyroCb and hydrometers below cloud base, indicating precipitation development. The resulting feedbacks suggest that vertical smoke transport efficiency was reduced slightly when compared with intense pyroCb events reaching the lower stratosphere. Physical and optical aerosol property measurements in pyroCb exhaust are compared with previous assumptions. A large suite of aerosol and gas-phase chemistry measurements sets a foundation for future studies aimed at understanding the composition of smoke plumes lifted by pyroconvection into the UTLS and their role in the climate system.

Pengaruh Penambahan Minyak Zaitun Terhadap Karakteristik dan Reologi Edible Film Berbahan Dasar Gluten

Gluten vegetable protein can be used as an alternative source of biopolymer as the basic material for edible film other than polysaccharides. Gluten-based edible films have a poor water vapor barrier and high cohesive and viscoelastic properties, therefore the addition of lipids and plasticizers is required. In this study, olive oil was added to reduce its permeability to water vapor, while glycerin was added to produce a more flexible edible film. The results showed that the addition of 1% olive oil could reduce the lowest water vapor transmission rate of 9.14 g/m2/24 hours with a thickness of 0.248 mm, tensile strength of 16.64 mPa, and elongation of 419.5%. The four characteristics are in accordance with the Japanese Industrial Standard. The antimicrobial testing on edible films showed that the addition of 0-2% olive oil could inhibit the growth of E. coli, while A. niger and R. oryzae 0-2% olive oil could not inhibit the growth of the two fungi. The measurement of optical properties showed that the transparency of the edible film was highest at the addition of 0% olive oil at 55%. The highest opacity value was with the addition of 1% olive oil, which is 2.96. The Fourier Transform Infrared (FTIR) identification showed that the edible film added with 1% olive oil had three characteristic absorption bands from gluten, olive oil, and an absorption band from glycerin. These bands indicate that olive oil, glycerin, and gluten do not react but only physically interact. The measurement using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) showed that the microstructure of gluten-based edible film produces a varied structure where the gluten structure network can be clearly observed and contains elements of C, O, N where the intensity of C and O elements of 160-400 cps and 30-100 cps, respectively.

Transparent Heat Shielding Properties of Core-Shell Structured Nanocrystalline CsxWO3@TiO2.

Nanocrystalline tungsten bronze is an excellent near-infrared absorbing material, which has a good potential application in the field of transparent heat shielding materials on windows of automobiles or buildings, but it exhibits serious instability in the actual environment, which hinders its further application. In this paper, we coated the CsxWO3 nanoparticles with TiO2 to prepare core-shell structured CsxWO3@TiO2, and its crystal structure and optical properties were studied. The results show that the surface of CsxWO3 nanoparticles is coated with a layer of TiO2 particles with the size of several nanometers, and the shell thickness can be adjusted by the amount of Ti source. The measurement of optical properties illustrates that TiO2-coated CsxWO3 exhibits good stability in actual environment, and its transparent heat shielding performance will decrease with the increase in TiO2 shell thickness. This work provides a new route to promote the applications of tungsten bronze as heat shielding materials.

Tunable optical nonlinearity of indium tin oxide for optical switching in epsilon-near-zero region.

The propagation of light in the epsilon-near-zero (ENZ) region of materials exhibits intriguing linear and nonlinear optical phenomenon that have been extensively exploited for a plethora of applications. Here, we show that the optical properties as well as the ENZ wavelength of magnetron-sputtered indium tin oxide (ITO) thin films could be judiciously engineered. The measurement of nonlinear optical properties reveals that the control of deposition conditions allows for the tuning of absorptive optical nonlinearity between saturable absorption and reverse saturable absorption. The ENZ wavelength for the ITO film is deduced as around 1553nm. We obtain the highest third-order nonlinear absorption coefficient and imaginary part of third-order nonlinear susceptibility for the ITO thin film through Z-scan method as -50.56 cm/GW and ∼38 × 10-14 e.s.u. at 1050nm, and -64.50 cm/GW and ∼45 × 10-14 e.s.u. at 1550nm, respectively. We demonstrate further that the strong saturable absorption of the ITO thin film enables Q-switched pulse laser generation in ∼1050 and ∼1550nm regions with tunable repetition rates and pulse energies. The present results suggest the great application potential of the ITO thin film in the field of nonlinear optical devices.

Optical Property Measurement and Temperature Monitoring in High-Intensity Focused Ultrasound Therapy by Diffuse Optical Tomography: A Correlation Study

In this article, we propose a new approach utilizing diffuse optical tomography (DOT) to monitoring the changes in tissues’ optical properties and temperature in high-intensity focused ultrasound (HIFU) therapy. By correlating the tissue reduced scattering coefficient (μs’) reconstructed by DOT and the temperature measured by a thermocouple, the quantitative relationship between μs’ and temperature in HIFU treatment was explored. The experiments were conducted using porcine and chicken breast muscle tissues during HIFU; the temperature of each tissue sample was recorded using a thermocouple. To incorporate the temperature dependency of tissue optical properties, both polynomial and exponential models were utilized to fit the experimental data. The results show that the change of μs’ during HIFU treatment could be detected in real-time using DOT and that this change of μs’ is quantitatively correlated with tissue temperature. Furthermore, while the tissue-type-dependent relationship between μs’ and temperature is non-linear in nature, it is stable and repeatable. Therefore, our approach has the potential to be used to predict temperature of tissue during HIFU treatment.

Shortwave infrared spatial frequency domain imaging for non-invasive measurement of tissue and blood optical properties.

.SignificanceThe shortwave infrared (SWIR) optical window (∼900 to 2000 nm) has attracted interest for deep tissue imaging due to the lower scattering of light. SWIR spatial frequency domain imaging (SWIR SFDI) provides wide-field tissue optical property measurements in this wavelength band. Key design and performance characteristics, such as portability, wavelength selection, measurement resolution, and the effect of skin have not yet been addressed for SWIR SFDI.AimTo fabricate and characterize a SWIR SFDI system for clinical use.ApproachThe optimal choice of wavelengths was identified based on optical property uncertainty estimates and imaging depth. A compact light-emitting diode-based dual wavelength SWIR SFDI system was fabricated. A two-layer inverse model was developed to account for the layered structure of skin. Performance was validated using tissue-simulating phantoms and in-vivo measurements from three healthy subjects.ResultsThe SWIR SFDI system had a resolution of at least at 880 nm and at 1100 nm. The two-layer inverse model reduced the error in deeper layer extractions by at least 24% in the phantom study. The two-layer model also increased the contrast between superficial vessels and the surrounding tissue for in-vivo measurements.ConclusionThe clinic-ready SWIR SFDI device is sensitive to small optical property alterations in diffuse media, provides enhanced accuracy in quantifying optical properties in the deeper layers in phantoms, and provided enhanced contrast of subcutaneous blood vessels.

Vertically Resolved Aerosol Chemistry in the Low Boundary Layer of Beijing in Summer.

Air quality in Beijing has been improved significantly in recent years; however, our knowledge of the vertically resolved aerosol chemistry in summer remains poor. Here, we carried out comprehensive measurements of aerosol composition, gaseous species, and aerosol optical properties on a meteorological tower in Beijing in summer and compared with those measured in winter. Our results showed that aerosol liquid water (ALW) contributing approximately 50% of the total mass with higher values aloft played a crucial role in aerosol formation. Particularly, the higher nitrate concentration in city aloft than at the ground level during daytime was mainly due to the enhanced gas-particle partitioning driven by ALW and particle acidity. The vertical profiles of organic aerosol (OA) factors varied more differently in the urban boundary layer. Although the ubiquitous decreases in primary OA with the increase in height were mainly due to the influences of local emissions and vertical convection, the vertical differences in oxygenated OA between summer and winter may be related to the photochemical processing of different biogenic and anthropogenic volatile organic compounds. The single-scattering albedo, brown carbon, and absorption Ångstrom exponent of aerosol particles also presented different vertical profiles between day and night due to the vertical changes in aerosol chemistry.

Investigating the effects of intermolecular interactions on nonlinear optical properties of binary mixtures with high repetition rate femtosecond laser pulses

Measurements of nonlinear optical (NLO) properties of different binary mixtures having carbon disulfide (CS2) as the common component, namely CS2-acetone, CS2-cyclopentanone, CS2-toluene, and CS2-carbon tetrachloride (CCl4), are carried out by using the z-scan technique. Open-aperture z-scan (OAZS) and close-aperture z-scan (CAZS) experiments are performed to determine the nonlinear absorption coefficient (β) and nonlinear refractive index (n2) of all binary liquid mixtures at various compositions of the components by employing a pulsed, high repetition rate (HRR) femtosecond laser. Also, we were able to use the flowing liquid to measure NLO properties in the CS2-acetone binary mixture to remove the cumulative thermal effects produced due to the pulsed HRR laser light. Nonlinear refractive index (n2) values are found to be influenced by the weak dipole-induced dipole intermolecular interactions between the nonpolar CS2 and polar acetone as well as cyclopentanone of the respective binary mixtures. On the contrary n2 values are not found to be affected by the intermolecular interactions in CS2-toluene and CS2-CCl4 binary mixtures. In comparison, the nonlinear absorption coefficient (β) values are not found to be affected by the same in all different sets of binary mixtures.

Structural and optical properties of Ba0.5Sr0.5TiO3 thin films on single crystalline substrates

The present investigation reports on structural and microstructural information of the Ba0.5Sr0.5TiO3 (BST-0.5) film deposited over single crystalline Si (100), MgO (100), and LaAlO3 (100) substrate using pulsed laser deposition (PLD) method. In this study, initial experiments were carried out by depositing BST-0.5 films at 1023 K and with oxygen partial pressures of 0.13 Pa and 13.33 Pa on Si (100) substrates. X-ray diffraction (XRD) analysis indicated the formation of a highly crystalline perovskite cubic phase for film deposited at substrate temperature 1023 K. Another set of depositions were carried out at the substrate temperature of 873 K and 1023 K and with oxygen partial pressure of 13.33 Pa. The XRD analysis indicated that deposition at 13.33 Pa has produced BST-0.5 films of increased crystallinity at the substrate temperature of 1023 K. Raman spectra obtained for BST thin film deposited on these three substrates confirmed the formation of the cubic phase. BST thin films were also prepared on LaAlO3 (100) and MgO (100) to investigate the optical properties of film prepared under the best deposition conditions such as 1023 K and 13.33 Pa. The bandgap energies were found to be in the range of 3.93–3.97 eV for these substrates. The measurements of optical properties of the BST-0.5 film coated on LaAlO3 substrate showed about ∼75% transmittance compared to MgO substrate. Higher extinction coefficient for the BST-0.5 thin film was observed for the film coated on MgO substrate in the UV and visible region compared to that of the film coated on LaAlO3 substrate. The refractive index as a function of wavelength was found to be 1.945 and 2.023 for BST-0.5 thin film coated on MgO and LaAlO3, respectively. The enhanced optical properties of the BST film coated on LaAlO3 substrate are discussed in relation to higher crystallinity and epitaxial growth of thin films obtained because of lower lattice mismatch.

Experience in the Application of Hydrocarbon Optical Studies in Oil Field Development

This article reviews the results of measurement of optical properties of oil, such as polarimetry, refractometric, luminescent-bituminological research, IR-spectrometry and UV-visible-NIR spectrometry used to solve geo-bituminology development of hydrocarbon deposits. The authors pay special attention to optical research in the field of UV-visible-NIR electromagnetic radiation, the results of which allow us to estimate the residual oil reserves, separate production for each formation during the operation of multi-layer objects, determine the producing gas-oil ratio, density and content of hydrocarbons, efficiency of hydraulic fracturing, flow-reducing technologies, and injection of solvents of heavy oil sediments, etc. The published approaches to methods of optical research, which are carried out by laboratories or in-well devices, have been analyzed. This article analyzes the main advantages and disadvantages of current technologies for determining the optical properties of oil. The authors propose wellhead devices for determining the optical properties of oil in UV-visible-NIR radiation (190–1100 nm) and their functional schemes, with a description of the operating principle.

Sustainable removal of 17α-ethynylestradiol from aqueous environment using rare earth doped lanthanum manganite nanomaterials

The pure water scarcity is a serious, emerging issue and this affects roughly the 40% of the world’s population thus new efficient wastewater treatment techniques are required. Lanthanum manganite (LaMnO3), is one of the most promising and efficient photocatalysts for the degradation of organic pollutants. In this work, undoped and Eu, Ho, Tb doped LaMnO3materials were successfully synthesized via sol–gel process using citric acid as chelating agent. The as-obtained samples are well crystallized within the perovskite structure and from the optical properties measurements it is determined that the value for the band gap energy is not influenced by the doping, i.e.Eg ~ 3.4 eV for all samples. In the photocatalytic studies,the potential water purification possibility is proved for the newly synthesized perovskite nanomaterials, and the best removal efficiency was reached in the presence of LMO:Ho, when 77% of endocrine disruptors EE2 (e.g. 17α-ethynilestradiol) was degraded after 30 min of UV irradiation. In addition, there usability of the LMO:Ho nanomaterials was also investigated. Based on the reutilization findings, it can be concluded that the mentioned photocatalyst has not lost its efficiency after three successive runs for photodegradation. Furthermore, the possible mechanism of the photocatalytic degradation of EE2, using different scavengers was also determined, and among the applied scavengers, the most important role had EDTA × 2Na, NaF and p-benzoquinone. According to our findings, the EE2 degradation mechanism mostly took place via positively charged holes,●OHadsradicals, as well as throughO2•−radicals, however they had a weaker effect on the degradation efficiency.

Preferential Location of Dopants in the Amorphous Phase of Oriented Regioregular Poly(3‐hexylthiophene‐2,5‐diyl) Films Helps Reach Charge Conductivities of 3000 S cm−1

AbstractDoping polymer semiconductors is a central topic in plastic electronics and especially in the design of novel thermoelectric (TE) materials. In this contribution, it has been demonstrated that doping of oriented semicrystalline P3HT thin films with the dopant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate), known as magic blue (MB), helps reach charge conductivities of 3000 S cm−1 and TE power factors of 170 ± 30 μW mK−2 along the polymer chain direction. A combination of transmission electron microscopy, polarized optical absorption spectroscopy, Rutherford backscattering, and TE property measurements helps clarify the conditions necessary to achieve such high charge conductivities. A comparative study with different dopants demonstrates that the doping mechanism is intimately related to the semicrystalline structure of the polymer and whether crystalline, amorphous or both phases are doped. The highest charge mobilities are observed when the dopant MB is preferentially located in the amorphous phase of P3HT, leaving the structure of P3HT nanocrystals almost unaltered. In this case, the P3HT nanocrystals are doped from their interface with the surrounding amorphous phase. These results indicate that doping preferentially the amorphous phase of semicrystalline polymer semiconductors is an effective strategy to reduce polaron localization, enhance charge mobilities, and improve TE power factors.

RbLiZn5(PO4)4 and BaLiZn3(PO4)3: two new zinc orthophosphates with all tetrahedra-based anion frameworks

Inorganic functional materials based on phosphates have attracted heavy attention due to diverse structures and ravishing properties. Two new zinc orthophosphates, RbLiZn5(PO4)4 and BaLiZn3(PO4)3, have been obtained through hydrothermal and high temperature solid reaction respectively. RbLiZn5(PO4)4, which is the first rubidium lithium zinc phosphate, crystallizes in a monoclinic space group of C2/c featuring a three-dimensional (3D) [LiZn5(PO4)4]– anion framework composed of parallel 2D [(Zn2(PO4)2]∞ slab and [ZnLi(PO4)4]∞ chains, which are formed by the ZnO4 and LiO4 groups connected with isolated PO4 groups. BaLiZn3(PO4)3, which is the first barium lithium zinc phosphate, crystallizes in an orthorhombic space group of Pccn with the 3D [(LiZn)Zn2PO7]4– anion skeleton created by two mirror-symmetric zigzag [Zn(ZnLi)O7]∞ chains connected with isolated PO4 groups through corner-sharing. The Rb+ and Ba2+ are located in the empty space of the structure as the counter cations. Besides crystal structures analysis, thermal stability and optical properties measurements as well as theoretical studies of the title phosphates were conducted.

Comments on “Experimental Measurement of Physical, Transport, and Optical Properties of Binary Mixtures of n‑Hexyl Pyridinium Nitrate [HPy][NO3] Ionic Liquid with Water, Ethanol, and Acetonitrile at 298.15 K and 101 kPa”

Comments on “Experimental Measurement of Physical, Transport, and Optical Properties of Binary Mixtures of n‑Hexyl Pyridinium Nitrate [HPy][NO3] Ionic Liquid with Water, Ethanol, and Acetonitrile at 298.15 K and 101 kPa”

Small Organic Molecular-Based Hybrid Halides with High Photoluminescence Quenching Temperature.

Organic-inorganic metal halides (OIMHs) exhibit excellent photoelectric properties; however, their high-temperature light-emission stability requires further improvement. Here, we report three isostructural OIMHs (C2H8N)4InCl7, (C2H8N)4SbCl7, and (C2H8N)4SbBr7 (C2H8N+ = dimethylammonium). They are all crystallized in the P21212 space group with a zero-dimensional (0D) structure, with orange-red photoluminescence (PL) under 365 nm UV excitation. Among them, (C2H8N)4InCl7 exhibits the strongest PL with a photoluminescence quantum yield (PLQY) of 13.9% at room temperature. Optical property measurements and density functional theory unveil that the luminescence of (C2H8N)4InCl7 at 405 and 620 nm is due to free exciton and self-trapped exciton emission, respectively. It is worth noting that (C2H8N)4InCl7 shows a high PL quenching temperature, maintaining 50% of its room-temperature PL intensity at 425 K, which is rare in OIHMs. This is much higher than the application temperature of phosphors in practical solid-state lighting applications (363-383 K). In this temperature range, the luminous intensity of (C2H8N)4InCl7 exceeds 60% of that at room temperature. The high PL quenching temperature observed in (C2H8N)4InCl7 indicates the potential of OIMHs for applications in phosphor-converted light-emitting diodes.

Direct measurement of optical properties of glacier ice using a photon-counting diffuse LiDAR

AbstractThe production of meltwater from glacier ice, which is exposed at the margins of land ice during the summer, is responsible for a large proportion of glacier mass loss. The rate of meltwater production from glacier ice is especially sensitive to its physical structure and chemical composition which combine to determine the albedo of glacier ice. However, the optical properties of near-surface glacier ice are not well known since most prior work has focused on laboratory-grown ice or deep cores. Here, we demonstrate a measurement technique based on diffuse propagation of nanosecond-duration laser pulses in near-surface glacier ice that enables the independent measurement of the scattering and absorption coefficients, allowing for a complete description of the processes governing radiative transfer. We employ a photon-counting detector to overcome the high losses associated with diffuse optics. The instrument is highly portable and rugged, making it optimally suited for deployment in remote regions. A set of measurements taken on Crook and Collier Glaciers, Oregon, serves as a demonstration of the technique. These measurements provide insight into both physical structure and composition of near-surface glacier ice and open new avenues for the analysis of light-absorbing impurities and remote sensing of the cryosphere.