Assessing the impact of polarization on soil moisture retrieval using C-band SAR data across diverse crop structures

This study aims to compare the therapeutic effects of hematoporphyrin monomethyl ether (HMME) and meta-tetrahydroxyphenylchlorin (m-THPC) under single-wavelength and dual-wavelength light irradiation in photodynamic therapy (PDT), and aims to optimize light source matching strategies to enhance targeted treatment of vascular lesions. This study employed the ABDA probe assay to evaluate the in vitro reactive oxygen species (ROS) generation efficiency of two photosensitizers (HMME and m-THPC) under 410, 532, 653 nm, and dual-wavelength (410 + 653 nm) irradiation. Using Leghorn chicken comb as a vascular malformation model, we further assessed in vivo vascular damage effects, thermal responses, tissue-level ROS production, and apoptosis rates. This study demonstrated that HMME exhibited optimal photodynamic efficacy at 410 nm, while m-THPC maintained substantial photodynamic efficacy at both 410 and 653 nm, with the dual-wavelength combination (410 + 653 nm) showing complementary activation for m-THPC but reduced efficacy for HMME. The 532 nm wavelength, though effective for vascular damage, caused significant thermal injury and non-specific apoptosis of non-target cells, highlighting its clinical limitations. Histopathological analysis confirmed that 410 and 653 nm irradiation selectively targeted vasculature with minimal epidermal damage, whereas 532 nm led to widespread tissue necrosis. ROS generation and apoptotic assays revealed that HMME's cytotoxicity was strongest at 410 nm, while m-THPC performed well across multiple wavelengths, and particularly benefited from dual-wavelength activation. Photosensitizer activation efficiency is highly wavelength-dependent, with HMME performing best at shorter wavelengths (410 nm) while m-THPC maintains considerable efficacy at longer wavelengths (653 nm). The dual-wavelength combination (410 + 653 nm) can partially overcome limitations of single wavelengths, providing references for clinical light source optimization.

The luminescence properties of N2,3-etheno-2-aminopurine (N2,3-ε2APu) have been studied using steady-state and time-resolved spectroscopy. N2,3-ε2APu was embedded in poly(vinyl alcohol) (PVA) polymer, which is known for effective immobilization of dissolved fluorophore molecules. Upon UV excitation, N2,3-ε2APu shows a bright dark-blue fluorescence with high fluorescence anisotropy, indicating efficient immobilization. Time-resolved fluorescence measurements show a somewhat heterogeneous lifetime, requiring a lifetime distribution model to fit the data. The fit reveals a central lifetime of about 5 ns and a half-width of the Lorentzian distribution of about 2 ns. We attribute this lifetime spread to the varying surroundings of fluorophore molecules in the polymer matrix. The N2,3-ε2APu-doped PVA films exhibit strong room-temperature phosphorescence (RTP) centered at 500 nm, with a lifetime of approximately 0.15 s. The excitation at 330 nm results in negative phosphorescence anisotropy. Interestingly, N2,3-ε2APu-doped PVA films can be directly excited to a triplet state at longer wavelengths (above 400 nm). This excitation results in a high positive phosphorescence anisotropy, reaching a value of 0.3 at about 450 nm. The ability to excite a molecule at longer wavelengths may find applications in the biomedical sciences, particularly in the study of photo-chemically labile proteins and their complexes with emitting ligands.

Hydrogen (H2) detection has become extremely important in recent years due to the increasing need for sustainable alternative energy sources. In this field, optical sensors can contribute significantly due to remote interrogation capabilities and the absence of ignition sources. Among the different H2 optical sensors, plasmonic sensors appear to be a very sensitive technology; however, they require expensive plasmonic materials like gold or silver, which, together with a palladium-sensitive layer, can increase the sensor cost. In addition, plasmonic bands are usually outside the ideal infrared range for remote interrogation, between 1500 and 1600 nm. This work presents a polymer-protected Tamm Plasmon Resonance (TPR) sensor with a well-defined resonance band at 1572 nm composed of SiO2, TiO2 layers, and palladium as a sensitive layer. This architecture can reduce the production cost of sensing structures, replacing plasmonic films with dielectric materials, while offering improved resonance definition at longer wavelengths. First, numerical calculations were carried out using the Transfer-Matrix Method to study the impact of the thickness of each layer, incidence angle, and light polarization on the resonance band wavelength and H2 sensitivity. The optimized structure was then fabricated, exhibiting a wavelength shift of 9.5 nm to 4 vol % of H2, a response time of 30 s, and no cross-sensitivity to methane or ammonia. The sensor also demonstrated high stability and resistance to environmental degradation up to eight days. These results emphasize the advantages of TPR structures for gas sensing in the infrared spectral range, opening new avenues for remote plasmonic sensing.

The under-coordinated Se80-xTe20Sbx (0 ≤ x ≤ 10) glasses were synthesized by melt quenching, and their optical and thermal properties were studied. Modulated Differential Scanning Calorimetry (MDSC) was performed to understand the glass transition (Tg), reversing and non-reversing heat flows, the specific heat jump at Tg (ΔCp), the strong and fragile nature of the melt, viscosity, and excess configurational entropy. Tg shows a continuous increase with the addition of antimony, suggesting that the structural network of Se80-xTe20Sbx glasses becomes more polymerized. Notably, the Se2Te6 rings in the structural network open up with the incorporation of Sb. A change in slope in Tg at x = 5 may indicate a transformation of the structural network comprising rings and chains to a complete chain-like structure. The glass forming ability, thermal stability, ΔCp, fragility, viscosity, and excess configurational entropy also exhibit a distinct change around x = 5. The near Arrhenius behavior of the viscosity with temperature indicates that the glass forming ability of Se80-xTe20Sbx melts is strong. The band gap shifted toward lower energy with an increase in Sb, and the FTIR cutoff also shifted toward longer wavelengths with an increase in lower-energy Sb-Te bonds. Under-coordinated yet with a strong nature of melts, these glasses can be studied for different optoelectronic and infrared applications.

Variability monitoring provides unparalleled insights into the atmospheric processes of brown dwarfs and directly imaged exoplanets. Inhomogeneous clouds, aurora e , and magnetic spots have all been postulated as potential drivers of variability. While objects at the L/T transition have had their variability studied extensively, the variability of early L dwarfs remain s an understudied region of the parameter space. We used observations from the Hubble Space Telescope in the near-infrared, using WFC3/G141 to disentangle the drivers of variability in three known variable early L dwarfs: 2MASS J1721039+334415, 2MASS J00361617+1821104, and 2MASS J19064801+4011089. We find that all three objects exhibit significant variability at all wavelengths, with white-light amplitudes of 0.53--1.41 $%$. We find that their colour variations are brighter and bluer compared to later spectral types, except for 2MASS J19064801+4011089, which exhibits largely grey variations. We report a new period for 2MASS J1721039+334415 of 4.9^ +0.4 _ -0.2 hours. We find evidence of long-term light curve stability in each object, which may indicate the presence of long-lived features on their surfaces. We created a flexible modelling framework to model three potential drivers of variability: clouds, aurorae, and magnetic spots. We fit our models to the spectral variability amplitude from 1.1-1.67 ̆pmum of each object. We find that changing cloud properties or magnetic spots are the most likely drivers of variability in each object. Auroral models do not reproduce the variability within the HST wavelengths; however, future observations at longer wavelengths that probe higher in the atmosphere may be more sensitive to auroral effects. This work provides a foundation for future variability studies of early L dwarfs and directly imaged exoplanets to disentangle auroral, cloud, and magnetic spot driven variability.

Abstract Dusty star-forming galaxies (DSFGs) have long been suspected to serve as the missing evolutionary bridge between the star-forming and quiescent phases of massive galaxy evolution. With the combined power of JWST and the Atacama Large Millimeter/submillimeter Array (ALMA), it is now possible to use high-resolution imaging at rest-frame ultraviolet (UV), optical, near-infrared (NIR), and submillimeter wavelengths to study the multiwavelength morphologies tracing both the stellar populations and dust during this key phase. We present the joint analysis of JWST/NIRCam imaging in GOODS-S and millimeter dust emission traced by ALMA for a sample of 33 galaxies at z = 1.5–5.5 selected from the 1.1 mm GOODS-ALMA 2.0 survey, and compare the morphologies of this population to mass- and redshift-selected samples of field star-forming and quiescent galaxies. The 1.1 mm selected sample is morphologically distinct from other similarly massive star-forming galaxies; we find a steeper size-wavelength gradient from 1.5 to 4.4 μ m, with a more dramatic decrease in size toward longer wavelengths. While the rest-NIR surface brightness profiles of the 1.1 mm selected galaxies are brighter in the inner regions relative to the field star-forming population, they are remarkably similar to the quiescent population. These morphological differences could suggest that DSFGs, unlike more typical star-forming galaxies, have already built up stellar mass in a severely dust-obscured core, leading to extended and clumpy morphologies at rest-UV and rest-optical wavelengths and more compact emission in the rest-NIR that is co-spatial with dust. If the bulge is already established, we speculate that millimeter-selected galaxies may imminently evolve to join their quiescent descendants.

Scaling power in mid-infrared (MIR) multimode fiber combiners is often limited by beam-brightness degradation caused by the unavoidable excitation of higher-order modes (HOMs). To circumvent this limitation, we report what we believe is the first demonstration of a 3 × 1 multimode tellurite fiber combiner employing an optimized double-tapered (DT) architecture. Unlike conventional designs, this device incorporates a secondary tapering stage that functions as a spatial mode filter to recover beam quality. The fabricated combiner exhibits a high single-port transmission efficiency of 86.1% at 1960nm. In a multi-wavelength demonstration covering the 2-3 µm band (1960, 2120, and 2770 nm), a total output power of ∼3.6 W was achieved with an overall efficiency of 80.1%. This efficiency is primarily limited by hydroxyl-induced absorption at longer wavelengths, which significantly outweighs the low fabrication excess loss (∼0.5 dB at 1960nm). Crucially, the DT design recovers the beam quality factor Mx/y2 from 15.9/13.9 (single-taper baseline) to 11.6/10.2. This enhancement yields a calculated brightness recovery ratio (BRR) of ∼1.8, validating the device as a compact and robust solution for brightness-conserving MIR all-fiber laser systems.

The construction of Dyson spheres, megastructures designed to capture the total radiative output of stars, can be one of the most compelling techno-signature scenarios for advanced extraterrestrial civilizations. By considering equilibrium temperatures, we investigate the luminosities and fluxes of Dyson spheres built around two promising classes of host stars: white dwarfs and red M-dwarfs. Using radiative balance arguments and representative stellar parameters, we compute the temperature–radius relationship for full energy interception and place these hypothetical structures on the Hertzsprung–Russell (H–R) diagram to assess their observational signatures. Our results show that Dyson spheres around white dwarfs produce cooler and fainter blackbody emissions, peaking in the near- to mid-infrared, while those around M-dwarfs radiate more strongly but at longer wavelengths. In both cases, the equilibrium temperature decreases as RD−1/2, while the total luminosity and observed bolometric flux remain fixed by the stellar output. These findings highlight the astrophysical suitability of low-luminosity stars as Dyson sphere hosts and provide practical constraints for future techno-signature searches using infrared surveys.

Abstract Brown Carbon (BrC), the light‐absorbing fraction of organic aerosols, plays a critical yet underappreciated role in atmospheric radiative forcing. Over the Indo‐Gangetic Plain (IGP), BrC is predominantly emitted from biomass burning associated with widespread biofuel use for heating and cooking, agricultural residue burning, and unregulated domestic waste burning. Despite its ubiquity, the molecular composition and optical behavior of BrC in this region is poorly understood. In this study, we present new molecular‐level evidence revealing substantial Near‐Infrared (NIR) light absorption by organic acids in the IGP. We investigated the chemical composition of nighttime BrC collected at a suburban site in the northwestern IGP by comparing two different seasons—post‐monsoon and winter, and two wind‐sectors—urban and rural. Aerosol samples were collected at the IISER Mohali Atmospheric Chemistry Facility, India. Compositional information was obtained by employing Direct‐Analysis in Real‐Time High‐Resolution‐Mass‐Spectrometry to analyze samples of organic aerosols collected on the filter spots of a 7‐wavelength aethalometer. Pronounced compositional differences appeared between urban‐influenced and rural‐influenced samples, although no significant seasonal variations were observed. Overall, organic aerosols in the region are dominated by nitrogen‐containing species. Urban‐influenced air‐masses are strongly affected by open burning of domestic waste, as reflected by the abundance of reduced‐nitrogen species. Notably, the presence of long‐chain organic acids, observed particularly in urban‐influenced samples, was found to enhance light absorption at longer wavelengths, extending into NIR, a spectral region traditionally attributed to black carbon (BC). This has critical implications for aerosol optical measurements, suggesting potential underestimation of BrC and overestimation of BC contributions.

Swept-source optical coherence tomography (SS-OCT) is an OCT variant with longer wavelengths than other commonly used OCT devices. Our aim was to determine the benefit of pre-operative SS-OCT to detect occult retinal pathologies in patients with advanced diabetic eye disease (ADED). Fundus photos and SS-OCT were performed pre-operatively in all patients scheduled for vitrectomy for ADED. These were reviewed by two retina specialists. A modified BIO-score based on the Nussenblatt scale of vitreous haze was used to evaluate fundus clarity on fundus photos. Findings on fundus photos were compared with the findings on SS-OCT. Any disagreement between the retina specialists was resolved upon discussion. We included 38 consecutive eyes of 35 patients. Various degrees of cataract was present in 22 eyes. In our sample, 84.2% of cases had a BIO score of 3 or more and 31.6% had a BIO score of 4 or 5. The most common diagnosis on fundus photos was vitreous haemorrhage (n = 23). Tractional retinal detachment (n = 20) was the most common diagnosis on SS-OCT. Only 3 cases had no view on SS-OCT. There was almost perfect (κ = 0.933, 95% CI: 0.887-0.979), substantial (κ = 0.734, 95% CI: 0.632-0.836) and moderate (κ = 0.593, 95% CI: 0.494-0.692) intergrader agreement for fundus photo diagnosis, SS-OCT diagnosis and BIO scores respectively. SS-OCT showed potential as an adjunct to clinical examinations, especially when hazy media opacities did not allow for a clear view of the fundus. However, it is important to recognise that OCT only serves as an adjunct and cannot be used as a definitive argument for assessing surgical feasibility.

Abstract Solar-type stars have been observed to flare at optical wavelengths with energies much higher than is observed for the Sun. To date, no counterparts have been observed at longer wavelengths. We searched the Very Large Array Sky Survey (VLASS) for radio emission associated with a sample of 150 solar-type stars that exhibit superflares in the Transiting Exoplanet Survey Satellite (TESS) data. Counterparts to six of these stars were present in VLASS as transient or highly variable radio sources. One star is detected in all three VLASS epochs, exhibiting an extreme level of apparently persistent radio emission. The engine for this radio emission is unclear, but may be related to accretion, a binary companion, or the presence of large-scale magnetic fields. Two stars show radio emission with a >50% circular polarization fraction, which likely indicates a coherent emission process. Overall, the VLASS-detected stars likely predominantly emit nonthermal, incoherent emission and tend to have higher flare rates and energies than the rest of our TESS sample. This, in addition to the VLASS-detected stars adhering to the Güdel–Benz relation, suggests that the radio emission may be associated with superflares and that the superflare phenomenon on solar-type stars extends to radio wavelengths, tracing particle acceleration. These data provide the first window into the luminosity function of radio superflares for solar-type stars and highlight the need for coordinated, multiwavelength monitoring of such stars to fully illustrate the stellar flare–particle acceleration relation.

The organization of the phase of electrical activity in the cortex is critical to inter-site communication, but the balance of this communication across large-scale (>8 cm), macroscopic (>1 cm), and mesoscopic (1 cm to 1 mm) ranges is an open question. The spatial frequencies (i.e. the spatial scales) of cortical waves have been characterized in the gray matter for micro- and mesoscopic scales of cortex and show decreasing spatial power with increasing spatial frequency. This research, however, has been limited by the size of the measurement array, thus excluding large-scale traveling waves. Obversely, poor spatial resolution of extracranial measurements prevents incontrovertible large-scale estimates of spatial power. We estimate the spatial frequency spectrum of phase dynamics in order to quantify the uncertain large-scale range, utilizing stereotactic electroencephalogram to measure local-field potentials within the gray matter. We take advantage of the large extent of spatial coverage of the cortical sheet, and irregular sampling is offset by use of linear algebra techniques. We find the spatial power of the phase is highest at the lowest spatial frequencies (longest wavelengths), consistent with the power spectra ranges for micro- and meso-scale dynamics, but here shown up to the size of the measurement array (up to 8-16 cm). This result arises across a wide range of temporal frequencies, from the delta band (1-3 Hz) through to the high gamma range (60-100 Hz).

Broadband long-wavelength infrared (LWIR) light sources in the molecular fingerprint spectral region are highly desirable for advanced spectroscopy and remote sensing applications. Intra-pulse difference frequency generation (IPDFG) driven by well-established erbium-doped fiber lasers has recently emerged as an efficient and compact approach for multi-octave LWIR radiation generation. Here, we demonstrate a highly efficient IPDFG with a spectrum spanning from 7.5 to 13 µm in a newly developed ZnGeP2 (ZGP) crystal namely, YS-ZGP, pumped by a few-cycle erbium-doped fiber laser. Benefitted from the high nonlinearity and reduced two-photon absorption in YS-ZGP, an output power of 5.48 mW and a conversion efficiency of 0.67% are obtained, which both represent record values in LWIR IPDFG systems, pumped by 1.55 µm femtosecond lasers. This result overturns the conventional perception that IPDFG in ZGP crystals can only be pumped at wavelengths longer than 2 µm. Furthermore, to extend the spectral coverage into longer wavelengths, IPDFGs in BaGa4Se7 and BaGa2GeSe6 crystals are investigated too, achieving octave-spanning LWIR outputs covering 8-16 µm and 7-16.5 µm, respectively. We anticipate that YS-ZGP-based LWIR sources pumped by 1.55 µm lasers will significantly advance practical applications in molecular spectroscopy and sensing.

Context. The solar chromosphere is a transition layer between the cool, dense photosphere and the hot, rarefied corona. This boundary region plays a key role in regulating energy transport and structuring the magnetic field throughout the solar atmosphere. Understanding its thermodynamic and magnetic properties is essential to model and interpret solar phenomena. Aims. This study investigates the theoretical properties and diagnostic potential of the polarisation signals in the Ca II H & K lines, with particular emphasis on their capability to probe magnetic fields in the upper chromosphere with the CHROMIS instrument at the Swedish 1-m solar telescope. Methods. We combine semi-empirical atmospheric models with high-resolution solar observations to model the formation of the Ca II H & K lines using non-local thermodynamic equilibrium radiative transfer calculations. The sensitivity of the lines to the magnetic field is examined through response functions and synthetic inversions, enabling an assessment of their diagnostic performance under realistic chromospheric conditions. Results. For typical chromospheric field strengths, the linear polarisation of the Ca II H & K lines is less than 1.7%, below the expected detection threshold of CHROMIS. However, their circular polarisation reaches more than 10% in strong-field regions, which is detectable by CHROMIS. Both lines are sensitive to magnetic fields in the upper chromosphere, with the K line forming slightly higher due to its larger opacity, and the H line exhibiting a somewhat stronger Zeeman sensitivity owing to its higher effective Landé factor and longer wavelength. Using the weak-field approximation, the line of sight magnetic field can be reliably inferred around log ξ ≈ −4. These results confirm that the Ca II H & K lines constitute powerful diagnostics for studying the magnetic structure of the upper solar chromosphere.

Wavelength shifters (WLS) offer a scalable and affordable approach to large-area photon detection. They absorb photons and re-emit them at longer wavelengths, enabling efficient light trapping by total internal reflection.We present a compact detector module based on WLS tiles coupled to silicon photomultipliers (SiPMs). The design exploits the geometry of elongated photodetectors placed along the tile edges to maximize photon collection without requiring large sensor surfaces. Particular attention was given to matching the spectral response of the WLS and the SiPMs to the Cherenkov emission peak.Laboratory tests with a pulsed UV laser provide preliminary measurements of the photon-detection efficiency and pulse shape. For the single-shift configuration, a preliminary photon-detection efficiency of about 20% was measured. First pulse-shape studies indicate a signal width of approximately 5 ns FWHM, reflecting the impact of wavelength shifting and optical reflections on signal broadening.While the absolute efficiency is lower than conventional solutions, the modularity and scalability of the system make it a promising candidate for large-area photon detection. Further studies will address detailed timing resolution and array-level performance.

Abstract Flux variability is a fundamental channel of information from Sgr A* because of its direct probe of processes occurring within an accretion disk under strong gravity. We present simultaneous JWST, NuSTAR, and Very Large Array observations of Sgr A* on 2024 April 5. We report the detection of a strong X-ray flare with a duration of about 40 minutes and a luminosity of 5.2 × 10 35 erg s −1 coincident with a bright near-IR (NIR) flare, and a brightening in radio about an hour later. We investigate the candidate physical mechanisms for the X-ray flare emission and conclude that this can best be explained by inverse Compton scattering of NIR flare radiation. We propose a dynamic scenario analogous to a coronal mass ejection in which a magnetic flux rope is ejected from Sgr A*’s inner accretion flow with a current sheet extending down from the rope to the bulk of the accretion flow. The accelerated electrons are continually ejected from the reconnection X-point with a bulk flow at the Alfvén speed of 0.7 c . IR radiation from the approaching energetic electrons is enhanced by beaming and upscattered by thermal electrons in the accretion flow to produce the strong X-ray flare. Meanwhile, the relativistic electrons moving in the opposite direction away from the disk experience weaker magnetic fields and so radiate at longer wavelengths. They feed into the magnetic flux tube explaining the detected delayed radio emission. This physical picture attempts to unify the origin of the variable emission from Sgr A* at IR, X-ray, and radio/submillimeter wavelengths.

Within the ultraviolet C (UVC) spectrum, the wavelengths in the 200-235 nm range, here named far-UVC, have been shown to effectively inactivate a variety of pathogens. Because of their limited penetration in biological materials, far-UVC wavelengths are anticipated to be minimally damaging to human skin and eyes. The germicidal efficacy of these wavelengths combined with a predicted low health hazard for humans suggests that far-UVC sources could operate continuously in indoor locations to reduce the risk of transmission of airborne diseases among occupants. While it is well-established that exposure to far-UVC light is minimally damaging to skin, concerns remain on the safety of exposed eyes. Scientific bodies overseeing UV radiation protection recommend eye safety limits based on published peer-reviewed data. To support this goal, our previous work used a 3D model of the human cornea to assess the wavelength dependence of corneal damage induced by UVC radiation; unlike relatively longer wavelengths, far-UVC wavelengths induced DNA dimers only in the uppermost layers of the corneal epithelium. Here, similar eye safety studies were extended to excised human corneas. The depth of DNA photodamage into the corneal epithelium was evaluated after exposure of the anterior surface to 50 mJ/cm2 or 100 mJ/cm2 from 222 nm or 254 nm light.

Abstract The 21 cm global spectrum provides an excellent window to observe the evolution of the early Universe. A high impedance receiver can be used in the global spectrum experiment, which offers a nearly uniform response over a large relative bandwidth, thus breaking the limitation imposed by the impedance matching between the antenna and receiver. This paper analyzes the measurement precision of the high-impedance receiver in the global spectrum experiment. We consider the main systematic errors: the vector network analyzer measurement error, the temperature measurement error, and the gain stability error. We use a Monte Carlo simulation to generate 10,000 sets of error combinations, and assess their impacts on observational results. For our experiment setup, we find that the level of systematic error is about 35 mK. This result is applicable to the Hongmeng Project (also known as the Discovering Sky at the Longest wavelength or DSL project), which will deploy an array of satellites on the cislunar orbit by a single rocket launch, to make low frequency imaging and global spectrum measurements. One of the satellites is dedicated to the 21 cm global spectrum observation in the 30–120 MHz frequency range, which employs a multi-receiver design scheme, to minimize systematic effects by cross-comparison of different receiving channels. The high-impedance channel is one to be used. Thus, within an acceptable range of systematic errors, the high-impedance receiver can provide a good measurement of the 21 cm signal, even if the 21 cm signal feature spans a broad frequency range.

Hybrid organic inorganic perovskites exhibit multifold advantages in their charge-transport performance and applications in optoelectronic devices. Mixtures of them during the synthesis process enable largely enhanced tunability in both the optical spectroscopic response of the materials and structural design of the light-emitting or photodetection devices. However, phase separation is usually observed in the mixture materials CH3NH3PbBrXI3-X (MAPbBrXI3-X) under optical excitation, which is based on the induced aggregation of iodine ions (I-) to the positively charged MA+, leading to a much modulated photoluminescence (PL) spectrum by a new feature at longer wavelengths. The available reports still lack insights into the dynamics of the responsible mechanisms. In this work, we employ CH3NH3PbBr1.5I1.5 as a typical example and 80 ps laser pulses at about 405 nm with varied repetition rate as the excitation. In addition to the intrinsic emission of MAPbBr1.5I1.5 at about 658 nm, a new spectral feature centered at about 734 nm is identified as the emission from the new phase with I--enrichment. Focusing on the emission spectrum around 734 nm, we were able to investigate how the phase-separation effect depends on the repetition rate, pulse energy, average power, and interaction time duration. Thus, these transient spectroscopic indications facilitate comprehensive understanding of the phase-separation mechanisms and determine the typical spectroscopic features accordingly in MAPbBrXI3-X.