Blackbody Radiation Research Articles

Scalable nano-architecture for stable near-blackbody solar absorption at high temperatures

Light trapping enhancement by nanostructures is ubiquitous in engineering applications, for example, in improving highly-efficient concentrating solar thermal (CST) technologies. However, most nano-engineered coatings and metasurfaces are not scalable to large surfaces ( > 100 m2) and are unstable at elevated temperatures ( > 850 °C), hindering their wide-spread adoption in CST. Here, we propose a scalable layer nano-architecture that can significantly enhance the solar absorption of an arbitrary material. Our electromagnetics modelling predicts that the absorptance of cutting-edge light-absorbers can be further enhanced by more than 70%, i.e. relative improvement towards blackbody absorption from a baseline value without the nano-architecture. Experimentally, the nano-architecture yields a solar absorber that is 35% optically closer to a blackbody, even after long-term (1000 h) high-temperature (900 °C) ageing in air. A stable solar absorptance of more than 97.88 ± 0.14% is achieved, to the best of our knowledge, the highest so far reported for these extreme ageing conditions. The scalability of the layer nano-architecture is further demonstrated with a drone-assisted deposition, paving the way towards a simple yet significant solar absorptance boosting and maintenance method for existing and newly developed CST absorbing materials.

The concept of the massive photon and its astrophysical implications

We discuss the concept of the massive photon with its possible implications in astrophysics. We use the term ”mass equivalent” instead of relativistic or effective mass. We also analyzed modified Planck’s law and estimated (mean mass/rest mass) ratio in connection to the temperature of blackbody radiation of the massive photons. This ratio diverges at high temperatures and approaches unity at low temperatures. The ”mass equivalent” for the CMB radiation was estimated to be equal to 0.0468% of the total mass of the Universe. We have discussed importance of the Breit-Wheeler process of particle – antiparticle production in the early Universe. We have evaluated the upper limit of the rest mass of the photon using gravitational and cosmological redshifts. A correlation was found between estimated masses of the photon and the lowest/highest frequencies of the spectral bands used for estimation of the mass.

On Wien’s peaks

Most Modern Physics Books contain a chapter on the Laws of Black Body radiation when introducing the principles of Quantum Mechanics. These laws govern many phenomena that we encounter in daily life, technological developments, and scientific research. For that, this old subject is still of great importance, and even now some issues require our attention. This work addresses one of these topics. We describe why it has no sense to think that the wavelength at which Planck’s black-body spectral radiance distribution plotted as a function of the wavelength has its maximum value, must be the same that the wavelength calculated from the peak value obtained when the distribution is plotted as a function of another variable, such as the energy of the photons. We will show how the issue lies in using the correct form to calculate this wavelength from measured quantities.

Temperature dependence of infrared photoresponse from lead sulfide film grown by chemical bath deposition

Due to the lower Auger recombination coefficient of lead salts, the study of room temperature infrared detectors based on lead salt is reemerges as a hot research topic. In this paper, we prepared polycrystalline lead sulfide (PbS) films using chemical bath deposition and fabricated a photovoltage infrared detector with Si. Different from normal PbS photodetectors, which usually show positive photoconductivity, our device demonstrated both positive and negative photoconductivity under 1550 nm laser illumination. The switching of positive and negative photoconductivity was found to be depended on temperature and applied bias. We proposed that the change of photoconductivity is due to the electron traps from S vacancies. Furthermore, we also tested the photoresponse under infrared blackbody radiation, which confirms that the device exhibits high sensitivity. The temperature dependence of PbS infrared photodetector demonstrated in this paper could be useful for applications involving focal array planes based on lead-related materials.

Stimulated radiative association of sodium and chlorine atoms and their ions in a coupled channel treatment.

In an extension of previous work (Šimsová et al., Phys. Chem. Chem. Phys., 2022, 24, 25250), we study stimulated radiative association of sodium chloride (NaCl) in an environment with a black body radiation. Colliding neutral (Na and Cl) and ionic (Na+ and Cl-) fragments are considered. The coupling between the diabatic ionic and neutral channels is accounted for. The cross sections are computed and resolved on the vibrational states of the formed NaCl molecule for detailed analysis. The thermal rate coefficients for neutral colliding fragments at kinetic temperatures, T, from 1 K to 5300 K are computed for use in astrochemical modelling. The total rate coefficient is affected by more than one order of magnitude by stimulated emission from a blackbody radiator of temperature Tb = 50 000 K. The effect from stimulated emission is largest for the lowest kinetic temperatures, where Tb of a few thousand kelvins has a significant effect. The rate coefficient for the colliding ionic fragments is calculated from 80 K to 3615 K. The blackbody radiation has little effect on this process.

What is the primary culprit that causes the "Doomsday Glacier" in Antarctica?

Antarctica, situated in the southernmost part of the earth is surrounded by the Southern Ocean. It has an extremely important role in tuning global climate, both because of its geographic location, and its giant ice mass, that comprises ~90% of the world's ice. In the past decades, the Thwaites Glacier in the Amundsen Sea of West Antarctica is undergoing the fastest recession in the region. The ice loss in Thwaites Glacier is currently responsible for roughly four percent of the global sea-level rise, which has been attributed to climate change and ocean warming. Due to the continuous collapsing and melting of Thwaites Glacier and the severe threat to humans, scientists gave it a terrifying name "Doomsday Glacier". With increasingly geological and geophysical studies conducted in West Antarctica, geothermal heat flux has been discovered to play a vital role in icesheet retreating. The rapidly retreating Thwaites and Pope glaciers are underlain by areas of largely elevated geothermal heat flow, which relates to the tectonic and magmatic history of the West Antarctic Rift System in this region, suggesting that this area is coupled to the dynamics of the underlying lithosphere. The collapsing and melting of the West Antarctic glaciers are without doubt a realistic and complex issue. From the current geological surveys, the heat flux of the crust of West Antarctica appears to be accelerating, coupled with frequent earthquakes and volcanoes. Geothermal features such as hot water lakes, thermal rivers, and giant ice caves beneath the glaciers have been continuously discovered. Therefore, it is reasonable to speculate that geothermal effects play a significant role in modifying the vast ice masses, causing glacier sliding, cracking, collapsing, and ultimately melting, and create conditions for a warming climate to melt West Antarctic glaciers. Many studies also suggest that warm ocean water is intruding beneath the glaciers across the grounding line, leading to melting of glacier bottom, which has been generally considered to be associated with human-emitted greenhouse gases, but it is thought here not to be a primary factor for glacier melting, but most likely a secondary factor. It is believed that primary and secondary factors, Milankovitch orbits, black body radiation, solar activities, human activities, and other factors are all interconnected to form a feedback loop between the glacier base and the ocean, or even a positive feedback loop, which further accelerates the collapsing and melting of the west Antarctic glaciers

A simple way to deduce the Planck equation of blackbody radiation emission

The blackbody radiation equation, also known as the Planck equation, has proved to be a challenge for students starting their studies in the field of thermal radiation, and this article aims to overcome this difficulty by presenting it in a simplified way. First, the classical approach to the blackbody derivation performed by the scientist Max Planck will be presented, which uses the concept of entropy, related to the different forms of energy distribution, in a thermodynamic system, complexion, according to Planck. Next, the deduction of the blackbody equation is presented, without resorting to complex calculations, but rather simple ones, from the approach carried out by Richard Feynman. Therefore, the objective of this article is to present the blackbody radiation equation, using basic concepts of average energy, and how the equation can be deduced from simple numerical calculations, without losing sight of the phenomenological character.

Theoretical calculation of “tune-out” wavelengths for clock states of Al<sup>+</sup>

In quantum optical experiments, the polarizabilities of atomic systems play a very important role, which can be used to describe the interactions of atomic systems with external electromagnetic fields. When subjected to a specific electric field such as a laser field with a particular frequency, the frequency-dependent electric-dipole (E1) dynamic polarizability of an atomic state can reach zero. The wavelength corresponding to such a frequency is referred to as the “turn-out” wavelength. In this work, the “turn-out” wavelengths for the 3s<sup>2</sup> <sup>1</sup>S<sub>0</sub> and 3s3p <sup>3</sup>P<sub>0</sub> clock states of Al<sup>+</sup> are calculated by using the configuration interaction plus many-body perturbation theory (CI+MBPT) method. The values of energy and E1 reduced matrix elements of low-lying states of Al<sup>+</sup> are calculated. By combining these E1 reduced matrix elements with the experimental energy values, the E1 dynamic polarizabilities of the 3s<sup>2</sup> <sup>1</sup>S<sub>0</sub> and 3s3p <sup>3</sup>P<sub>0</sub> clock states are determined in the angular frequency range of (0, 0.42 a.u.). The “turn-out” wavelengths are found at the zero-crossing points of the frequency-dependent dynamic polarizability curves for both the 3s<sup>2</sup> <sup>1</sup>S<sub>0</sub> and 3s3p <sup>3</sup>P<sub>0</sub> states. For the ground state 3s<sup>2</sup> <sup>1</sup>S<sub>0</sub>, a single “turn-out” wavelength at 266.994(1) nm is observed. On the other hand, the excited state 3s3p <sup>3</sup>P<sub>0</sub> exhibits four distinct “turn-out” wavelengths, namely 184.56(1) nm, 174.433(1) nm, 121.52(2) nm, and 119.71(2) nm. The contributions of individual resonant transitions to the dynamic polarizabilities at the “turn-out” wavelengths are examined. It is observed that the resonant lines situated near a certain “turn-out” wavelength can provide dominant contributions to the polarizability, while the remaining resonant lines generally contribute minimally. When analyzing these data, we recommend accurately measuring these “turn-out” wavelengths to accurately determine the oscillator strengths or reduced matrix elements of the relevant transitions. This is crucial for minimizing the uncertainty of the blackbody radiation (BBR) frequency shift in Al<sup>+</sup> optical clock and suppressing the systematic uncertainty. Meanwhile, precisely measuring these “turn-out” wavelengths is also helpful for further exploring the atomic structure of Al<sup>+</sup>.

Absolute calibration method of electron cyclotron emission imaging system on EAST tokamak

<sec>Electron cyclotron emission imaging (ECEI) system can provide the poloidal two-dimensional (2D) relative electron temperature perturbation profile of the core plasma with high spatial and temporal resolution. After absolute calibration of ECEI system, 2D absolute electron temperature profile and its perturbation can be provided. It can provide experimental data support for studying the local heat transport and the evolution of magnetic surface of macro magneto-hydro-dynamics instability. However, due to a large number of measurement channels and the wide measuring area of ECEI diagnostic system, the absolute calibration method in which a blackbody radiation source is used as a standard source, still has technical difficulties.</sec><sec>This paper provides an absolute calibration method of ECEI diagnostic system on EAST tokamak, which can cover all the channels of ECEI system. Firstly, the sawtooth inversion surface can be determined by measuring the relative electron temperature change before and after the collapse of the sawtooth. The magnetic surface position and the shape (<inline-formula><tex-math id="M1">\begin{document}${S_{{\text{inv}}}}$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240497_M1.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240497_M1.png"/></alternatives></inline-formula>) of the ECEI measuring area are fitted based on the position and shape of the inversion surface. Then, the one-to-one mapping relationship between laboratory coordinates of each ECEI channel and magnetic surface is obtained. Secondly, according to the assumption that the electron temperature is the same on each magnetic surface in equilibrium, the electron temperature of each magnetic surface is fitted by the electron cyclotron emission (ECE) system result, while the ECE system is absolutely calibrated. The calibration coefficient <i>k</i>(<i>i</i>, <i>j</i>) of each ECEI channel is obtained by comparing with the signal amplitude and the electron temperature on the magnetic surface. The relative error of absolute electron temperature between ECEI and ECE is no more than 6% at the same location.</sec><sec>Based on the absolute electron temperature profile provided by ECEI, the motion of the magnetic axis during sawtooth instability can be tracked. It is found that the radial displacement of the magnetic axis occurs followed by the poloidal displacement during sawtooth collapse. This result indicates that after absolute calibration, the ECEI system can provide more abundant information about experimental research.</sec>

Gallium Fixed-point Blackbody Radiation Source for Calibration of Sea Surface Temperature Radiometer

Gallium Fixed-point Blackbody Radiation Source for Calibration of Sea Surface Temperature Radiometer

Minimally-intrusive, dual-band, fiber-optic sensing system for high-enthalpy exhaust plumes

<abstract> <p>The propulsion research lab at Utah State University has developed a minimally-intrusive optical sensing system for high-temperature/high-velocity gas-generator exhaust plumes. For this application glass fiber-optic cables, acting as radiation conduits, are inserted through the combustion chamber or nozzle wall and look directly into the flow core. The cable transmits data from the flame zone to externally-mounted spectrometers. In order to capture the full-optical spectrum, a blended dual-spectrum system was employed, with one spectrometer system tuned for best-response across the visible-light and near-infrared spectrum, and one spectrometer tuned for best-response in the near- and mid-infrared spectrum. The dual-band sensors are radiometrically-calibrated and the sensed-spectra are spliced together using an optimal Wiener filtering algorithm to perform the deconvolution. The merged spectrum is subsequently curve-fit to Planck's black-body radiation law, and flame temperature is calculated from associated curve maxima (Wien's law). The presented fiber-optic sensing systems performs a function that is analogous to Raman spectroscopy. The system non-contact, high-temperature measurement, and does not interfere with the heat transfer processes. In this report data collected from a lab-scale (200 N) hybrid rocket system are analyzed using the described method. Optically-sensed flame-temperatures are correlated to analytical predictions, and shown to generally agree within a few degrees. Additionally, local maxima in the optical spectra are shown to correspond to emission frequencies of atomic and molecular oxygen, water vapor, and molecular nitrogen; all species known to exist in the hybrid combustion plume. Presented data demonstrate that selected fiber-optics can survive temperature greater than 3000 ℃, for durations of up to 25 seconds.</p> </abstract>

Illuminating a bacterial adaptation mechanism: Infrared-driven cell division in deep-sea hydrothermal vent environments

<p>Based on Planck's black-body radiation law, deep-sea hydrothermal vent chimneys emit light, predominantly infrared light, which potentially supports bacterial photosynthesis in this ecosystem independently of the solar energy. To investigate the impact of this geothermal light on bacterial growth, we collected samples from the Southwest Indian Ridge and demonstrated that infrared light alone promotes bacterial growth and alters population composition. The mechanism of infrared stimulated growth was analyzed by monitoring cell wall synthesis using the <i>Tepidibacter hydrothermalis</i> strain SWIR-1, which was isolated from cultures enriched through infrared irradiation. The results showed that the elevated hydrostatic pressure inhibited septal peptidoglycan synthesis and cell division, but had less effect on cell elongation, chromosome replication and segregation. The dominant cell shape was filaments with some swelling and inertness in cell wall synthesis depending on the level of pressure applied. Interestingly, irradiation with 880 nm infrared light effectively initiated septal synthesis and alleviated the obstruction. This revelation uncovers a novel adaptation mechanism involving infrared light for bacteria dwelling in deep-sea environments, and sheds light on the potential of infrared-mediated photobiomodulation.</p>

Optimization of Multi-Junction Solar Cells for the Orbit of Mars

Photovoltaic (PV) devices have been used in space applications since 1958 and need to be constantly optimized in terms of specific power (W/kg). For the next decade, Mars is one important pursued destination by NASA and, as such, optimized PV designs will be needed. This work presents optimal designs in terms of bandgap energy configuration for multijunction solar cells operating at the Mars’ orbit conditions. For this, a physical model using blackbody radiation was implemented to calculate the solar spectrum at different orbital points and the PV solar cell temperature. By means of a computer simulation based on the Schockley-Queisser detailed balance model, power conversion efficiencies are mapped and the optimal bandgap energy combination is obtained for each configuration. As results, we obtained for the optimized double junction solar cell an efficiency of 45.3% with bandgaps of 0.90/1.60 eV and 51.7% for the best triple junction solar cell with bandgaps of 0.75/1.22/1.84 eV.

Accurate Determination of Blackbody Radiation Shifts in a Strontium Molecular Lattice Clock.

Molecular lattice clocks enable the search for new physics, such as fifth forces or temporal variations of fundamental constants, in a manner complementary to atomic clocks. Blackbody radiation (BBR) is a major contributor to the systematic error budget of conventional atomic clocks and is notoriously difficult to characterize and control. Here, we combine infrared Stark-shift spectroscopy in a molecular lattice clock and modern quantum chemistry methods to characterize the polarizabilities of the Sr_{2} molecule from dc to infrared. Using this description, we determine the static and dynamic blackbody radiation shifts for all possible vibrational clock transitions to the 10^{-16} level. This constitutes an important step toward millihertz-level molecular spectroscopy in Sr_{2} and provides a framework for evaluating BBR shifts in other homonuclear molecules.

Satyendra Nath Bose: quantum statistics to Bose-Einstein condensation

Satyendra Nath (S.N.) Bose is one of the great Indian scientists. His remarkable work on the black body radiation or derivation of Planck’s law led to quantum statistics, in particular, the statistics of photon. Albert Einstein applied Bose’s idea to a gas made of atoms and predicted a new state of matter now called Bose-Einstein condensate. It took 70 years to observe the predicted condensation phenomenon in the laboratory. With a brief introduction to the formative period of Professor Bose, this research survey begins with the founding works on quantum statistics and, subsequently, provides a brief account of the series of events terminating in the experimental realization of Bose-Einstein condensation. We also provide two simple examples to visualize the role of synthetic spin-orbit coupling in a quasi-one-dimensional condensate with attractive atom-atom interaction.

Some Interesting Facts About Planck’s Law of Blackbody Radiation

Introductory textbooks of Modern and Thermal Physics discuss the Planck radiation law as a backbone of the blackbody radiation spectrum. This law is used to explain the intensity of blackbody radiation as a function of either frequency or wavelength at a given temperature. In the introductory coursework, the Planck’s formula is also used to study other blackbody radiation laws such as Stefans–Boltzmann law, Wien’s Displacement law, Rayleigh–Jeans Law and Wien’s Distribution law. In this work, we highlight some interesting facts related to the total energy density, photon number density and average energy of photon of blackbody radiation. The main objective of this work is to focus on the lesser known features associated with physics of blackbody radiation. We believe that these simple analytic calculations may give very useful and interesting information about the Planck radiation law to the undergraduate students.

The Frayer Model as Analysis of Instruction and Student Knowledge in Undergraduate Astronomy

The American public’s factual knowledge about science has remained relatively unchanged over the past two decades. Research on scientific literacy connects to science education, interactive instruction techniques, and how introductory undergraduate science courses are many students’ last formal exposure to science. This highlights a need for research on how these courses can contribute toward a scientifically-literate citizenry. This study qualitatively analyzes how instruction in an introductory undergraduate astronomy course informs students on an astronomy concept, specifically blackbody radiation. A case study method of thematic analysis was employed by administering a pre- and post-lesson Frayer Model to students in an ASTR 1010 section and recording the professor’s lecture. Thematic analysis was conducted on all Frayer Models and the lecture transcript. Three key themes (refined understanding, blackbody spectrum, and ideal physical body) emerged, summarizing how students’ knowledge changed following instruction. The results section contextualizes these themes within how the concepts were taught. Blackbody radiation was entirely foreign to most students. Students utilized a few keywords, such as “perfect absorber,” to describe blackbodies. Their visual comprehension improved, for they accurately drew and labeled blackbody spectra. This study is novel in using the Frayer Model as an assessment tool in astronomy education research. The findings contextualize scientific literacy and nuance our understanding of how students conceptualize lecture-based instruction. Educators can interpret the results when considering how to teach blackbody radiation. Implications are made to a growing body of knowledge on language in astronomy education.

Blackbody radiation and photoelectric effect: continuing education for teachers

This work reports an activity conducted at the University of São Paulo (USP-School) Meeting in January 2022, intended for teachers in the field of Exact and Earth Sciences, in the mode of continuing education. It involves a dialogued and interactive activity, with hands-on practical activities (do it yourself) and suggestions for implementation with high school students in face-to-face or online classroom settings. The purpose of the proposal is to review and delve into topics related to Modern and Contemporary Physics (MCP) along with Physics educators working in Basic Education. Additionally, it aims to bring about reflection on pedagogical practices and collective consideration of alternative approaches to addressing MCP subjects, taking into account the students' potential and interests. To evaluate the proposal, an online questionnaire was administered, consisting of an open-ended question and other closed-ended questions. According to the teachers who participated in the course and responded to the questionnaire, the time dedicated to completing the course was beneficial for exchanging experiences, deepening knowledge, and gaining access to materials to be used in the classroom. In this sense, the proposal achieved its objective.

Sensitive Thermography via Sensing Visible Photons Detected from the Manipulation of the Trap State in MAPbX3.

Sensitive thermometry or thermography by responding to blackbody radiation is urgently desired in the intelligent information life, including scientific research, medical diagnosis, remote sensing, defense, etc. Even though thermography techniques based on infrared sensing have undergone unprecedented development, the poor compatibility with common optical components and the high diffraction limit impose an impediment to their integration into the established photonic integrated circuit or the realization of high-spatial-resolution and high-thermal-resolution imaging. In this work, we present a sensitive temperature-dependent visible photon detection in Bi-doped MAPbX3 (X = Cl, Br, and I) and employ it for uncooled thermography. Systematic measurements reveal that the Bi dopant introduces trap states in MAPbX3, thermal energy facilitates the carriers jumping from trap states to the conduction band, while the vacancies of trap states ensure the sequential absorption of visible photons with energy less than the band gap. Subsequently, the change of response toward the visible photon is applied to construct the thermograph, and it possesses a specific sensitivity of 2.11% K-1 along temperature variation. As a result, our thermograph presents a temperature resolution of 0.21 nA K-1, a high responsivity of 2.06 mA W-1, and a high detectivity of 2.08 × 109 Jones at room temperature. Furthermore, remote thermal imaging is successfully achieved with our thermograph.

A Theoretical Study of Temperature-dependent Photodissociation Cross Sections and Rates for O2

The photodissociation of O2 is thought to play a vital role in blocking UV radiation in the Earth’s atmosphere and likely has great importance in characterizing exoplanetary atmospheres. This work considers four photodissociation processes of O2 associated with its four electronic states, whose potential energy curves and transition dipole moments are calculated at the icMRCI+Q/aug-cc-pwCV5Z-DK level of theory. The quantum-mechanical approach is used to compute the state-resolved cross sections for two triplet transitions from the ground X state to the excited B and E states, and for two singlet transitions from the a 1Δg and b states to the 1 1Πu state, with a consideration of photon wavelengths from 500 Å to the relevant threshold. Assuming the populations of the initial states satisfy a Boltzmann distribution, the temperature-dependent photodissociation cross sections are estimated at gas dynamic temperatures of 0–10,000 K, in which the discrete progressions of the B and E transitions are also considered. The photodissociation rates of O2 in the interstellar, solar, and blackbody radiation fields are also calculated using the temperature-dependent cross sections. The resulting photodissociation cross sections and rates are important for the atmospheric chemistry of Earth and may be also useful for the atmospheric exploration of exoplanets.