The Dust Mass of Supernova Remnants in M31

The dust temperature and mass of the supernova remnants (SNRs) in M31 are estimated by fitting the infrared spectral energy distribution calculated from the images in the Spitzer/IRAC4 and MIPS24, Herschel/PACS70, 100, and 160, and Herschel/SPIRE 250 and 350 μm bands. Twenty SNRs with relatively reliable photometry exhibit an average dust temperature of 20.1 − 1.5 + 1.8 K, which is higher than the surrounding and indicating the heating effect of supernova explosion. The dust mass of these SNRs ranges from about 100 to 800 M ⊙, much bigger than the SNRs in the Milky Way. On the other hand, this yields the dust surface density of 0.10 − 0.04 + 0.07 M ⊙ pc−2, about half of the surrounding area, which implies that about half dust in the SNRs is destroyed by the supernova explosion. The dust temperature, the radius, and thus the dust mass all demonstrate that the studied SNRs are old and very likely in the snowplow or even fade-away phase because of the limitation by the far distance and observation resolution of M31, and the results can serve as a reference to the final effect of supernova explosion on the surrounding dust.

Label-Free Diagnosis of Pulmonary Fat Embolism Using Fourier Transform Infrared (FT-IR) Spectroscopic Imaging

The diagnosis of pulmonary fat embolism (PFE) is of great significance in the field of forensic medicine because it can be considered a major cause of death or a vital reaction. Conventional histological analysis of lung tissue specimens is a widely used method for PFE diagnosis. However, variable and labor-intensive tissue staining procedures impede the validity and informativeness of histological image analysis. To obtain complete information from tissues, a method based on infrared imaging of unlabeled tissue sections was developed to identify pulmonary fat emboli in the present study. We selected 15 PFE-positive lung samples and 15 PFE-negative samples from real cases. Oil red O (ORO) staining and infrared spectral imaging collection were both performed on all lung tissue samples. And the fatty tissue of the abdominal wall and the embolized lipid droplets in the lungs were taken for comparison. The results of the blind, evaluation by pathologists, showed good agreement between the infrared spectral imaging of the lung tissue and the standard histological stained images. Fourier transform infrared (FT-IR) spectroscopic imaging significantly simplifies the typical painstakingly laborious histological staining procedure. And we found a difference between lipid droplets embolized in abdominal wall fat and lung tissue.

Achievement of 0.005 % combined transfer uncertainties in the NIST detector calibration facility

Improvements in a lamp-monochromator-based facility at the National Institute of Standards and Technology (NIST), the Visible near-infrared Spectral Comparator Facility (VisSCF) which is used to calibrate optical detectors for spectral radiant power responsivity from 300 nm to 1100 nm, are described. These changes include extending the VisSCF operational range down to 300 nm from 350 nm, thereby fully covering the ultraviolet-A (UVA) spectral region and partially covering the UVB range. These improvements have lowered the magnitudes of most of the components in the uncertainty budget and have led to combined 0.005 % transfer (k=1) uncertainties in the spectral power responsivity calibrations over most of the spectral range. Redevelopment of the uncertainty budget results in total expanded uncertainties of spectral responsivities of less than 0.1 % (k=2) over the spectral range from 380 nm to 980 nm, with the greatest uncertainty term coming from the calibrations of the transfer standards.

Integrated near-infrared spectral sensing

Spectral sensing is increasingly used in applications ranging from industrial process monitoring to agriculture. Sensing is usually performed by measuring reflected or transmitted light with a spectrometer and processing the resulting spectra. However, realizing compact and mass-manufacturable spectrometers is a major challenge, particularly in the infrared spectral region where chemical information is most prominent. Here we propose a different approach to spectral sensing which dramatically simplifies the requirements on the hardware and allows the monolithic integration of the sensors. We use an array of resonant-cavity-enhanced photodetectors, each featuring a distinct spectral response in the 850-1700 nm wavelength range. We show that prediction models can be built directly using the responses of the photodetectors, despite the presence of multiple broad peaks, releasing the need for spectral reconstruction. The large etendue and responsivity allow us to demonstrate the application of an integrated near-infrared spectral sensor in relevant problems, namely milk and plastic sensing. Our results open the way to spectral sensors with minimal size, cost and complexity for industrial and consumer applications.

Infrared Absolute Calibration. I. Comparison of Sirius with Fainter Calibration Stars

A challenge in absolute calibration is to relate very bright stars with physical flux measurements to faint ones within range of modern instruments, e.g., those on large ground-based telescopes or the James Webb Space Telescope (JWST). We propose Sirius as the fiducial color standard. It is an A0V star that is slowly rotating and does not have infrared excesses due to either hot dust or a planetary debris disk; it also has a number of accurate (∼1%–2%) absolute flux measurements. We accurately transfer the near-infrared flux from Sirius to BD +60 1753, an unobscured early A-type star (A1V, V ≈ 9.6, E(B – V) ≈ 0.009) that is faint enough to serve as a primary absolute flux calibrator for JWST. Its near-infrared spectral energy distribution and that of Sirius should be virtually identical. We have determined its output relative to that of Sirius in a number of different ways, all of which give consistent results within ∼1%. We also transfer the calibration to GSPC P330-E, a well-calibrated close solar analog (G2V). We have emphasized the 2MASS K S band, since it represents a large number and long history of measurements, but the theoretical spectra (i.e., from CALSPEC) of these stars can be used to extend this result throughout the near- and mid-infrared.

Исследование плазмонного резонанса в Bi-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=- и Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- методом инфракрасной спектральной эллипсометрии

In the infrared region of the spectrum (IR), the optical properties of single-crystal samples of narrow-gap degenerate semiconductors Bi2Se3 and Sb2Te3 are investigated by infrared spectral ellipsometry (SE). The transport properties of the Drude fitting of dielectric functions obtained by spectroscopic ellipsometry are studied. The behavior of the bulk and surface plasmon polaritons is investigated in detail. The dispersion and mean free path of the plasmon, the depth of the skin layer for the conducting and dielectric surfaces are calculated. The contribution of the plasmon to the optical properties is estimated from the spectral density for the Bi2Se3 and Sb2Te3 samples.

Синхронное управление прошедшим и отраженными светом в полупроводниковых хромхалькогенидных шпинелях

A way for synchronous control of the intensity of transmitted and reflected light in magnetic semiconductors by an external magnetic field is proposed in the infrared spectral region. For illustration, we obtained the magnetoreflection and magnetotransmission spectra of unpolarized light in single crystals of Hg(Cd)Cr2Se4 spinel.