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Questions tagged [infrared-radiation]

A region of the electromagnetic radiation spectrum where wavelengths range from about 700 nm to 1mm

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The absorption of infrared light for regular materials, like fabric wallets backpacks and clothes

I work as a brand partner for a company that produces a patch which strengthens the production of stemcells in the body. The patches are activated with the help of the bodys own infrared radiation. I ...
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Why is my pyrgeometer calibrated as if it has $a >1$ emissivity?

I've acquired an SL-510-SS upward-looking pyrgeometer. In the manual it gives the formula for how to compute the downwelling infrared it picks up: Clearly the $k_2$ coefficient is the emissivity of ...
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Does anyone know of a molecule or material that has a strong and sharp absorption peak at 2 microns? [closed]

My lab studies quantum imaging, and we are having some (surprising) difficulty finding an interesting (doesn't have to be) molecule or material that has a sharp absorption peak at 2 microns. If anyone ...
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Can very flat surfaces radiate heat in a mostly-perpendicular manner?

What determines the direction (i.e. angle) at which an emitted photon travels? Are very flat surfaces more spatially-coherent (i.e. the photons travel in a parallel manner, akin to a laser beam) or ...
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Does infrared radiation emitted by an object happen only from its surface, or is emission also from the centre of the object?

Textbook answer of how radiation is emitted is from the surface. Does the inside of a object also emit infrared?
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Can infrared light pass through solid materials

I have an IR sensor at about few tens of mm (millimeter) from a heating source (incandescent bulb or heating element). The phototransistor in my sensor is lead lined but I guess it is sensitive to a ...
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Anomaly in Photoelectric effect

Good day. While doing a physics experiment for a university assignment, I was tasked with measuring the maximum wavelength at which a potassium cathode shined by a monochromatic light emits electrons. ...
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Will an HVAC vent interfere with an Infrared Sensor?

A 360 degree ceiling mount infrared sensor is to be installed in the center of a small room. An HVAC (heating, ventilation & Air Conditioning) register is located in the ceiling, near the center ...
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What is the influence of humidity on NDIR $\rm CO_2$ measurements?

The Question I would like to use an NDIR $\rm CO_2$ sensor to measure $\rm CO_2$ in the 0.1-3% range. However, in the course of my experiments, humidity may vary from ambient (50-60%) up to nearly 100%...
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Effect of having infrared reflective paint on a room with and without a heat source

I am trying to check if my understanding is correct. This is not really a question but a request for validation. I hope this is allowed. When painting with a heat reflective paint there are two ...
Ahmad Makarem's user avatar
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Why does radar have a much longer range than infrared sensors? (in the context of military aircraft)

In the context of military aircraft and missiles, radars often have ranges of hundreds of kilometers, while thermal infrared sensors can only barely reach 100 km in the best of circumstances. But ...
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Are there any material coatings that would currently be effective to counter the rise of directed energy weapons?

I've been reading into directed energy weapons recently, and they seem like they're going to be a gamechanger. I'm just curious as to material countermeasures. I've learnt that some dielectric mirrors ...
Theo Godfrey's user avatar
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Oscillation in the FTIR spectrum

An FTIR spectrum was measured for me (device from Alignment and MCT Detector) and since I'm not very familiar with FTIR I'm looking for some advice. The absorbance spectrum was obtained by measuring ...
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Larmor precession with an oscillating field?

With a non-polar molecule like CO2, presumably Larmor precession doesn't apply. However, CO2 has a mode of vibration that induces an oscillating dipole moment. Could something similar to Larmor ...
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Why do IR spectra of calculation and experiment differ?

Recently I was simulating the IR spectra ( 400-3500 $cm^{-1}$ ) of an aromatic-like molecule with DFT. Then I did a comparison to the available experimental data. Most data fitted well together: ...
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Finding absorption coefficient of boron doped silicon

I want to find absorption coefficient of boron doped silicon film with 0.08mm height but the curve i found is of 2mm. According to beer law, coefficient is inverse ly proportional problem is I think ...
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Can mirrors on the inside of a container reflect infrared radiation thereby keeping the contents inside warmer for longer?

So I was wondering if it was possible to prolong the "entropy" of the bottle by making sure the heat of the contents of the inside of the bottle doesn't escape by first having a secondary ...
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DIY Spectrophotometer doesn't work properly in the IR range

I've built an optical spectrometer by following the instruction given on the Theremino website: Theremino_Spectrometer_Construction.pdf, but I'm having a little issue with it. Everything works ...
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My phone sees the NIR from a TV remote. Why does it not see the NIR in rainbows?

My Pixel phone's camera shows the IR light from the LED of a TV remote as a magenta/lavender color. That wavelength is likely around 940 nm. Now, when I take a picture of a rainbow in the sky, it does ...
Guillaume's user avatar
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Weinberg's virtual soft photon addition to Feynman diagrams

I am reading Weinberg's book on QFT, especially Chapter 13.2, talking about the effect of adding virtual soft photons to a Feynman graph in the theory of QED. Weinberg supports that adding $N$ virtual ...
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What's an inexpensive way to measure the amount of UV light (or IR light) given off by a light bulb? [closed]

What's an inexpensive way to measure the amount of UV light (or IR light) given off by a light bulb? Specifically, the amount at various wavelengths of UV (and IR)?
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How can infrared light interact with nerve cells given the wavelength is so much longer than the cell's size?

I obviously do not understand how a wavelength greater in length than a cell can be detected by a cell. As I understand it, infrared ranges from 300GHz to hundreds of THz. As an example, if an ...
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Is using a variable based on near infrared radiation to predict a variable based on thermal infrared a circular exercise?

I am creating a model which aims to predict a Land Surface Temperature related variable (from satellite thermal infrared measurements) which uses a vegetation related variable (created using satellite ...
Francis's user avatar
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Why is my aluminum foil emitting the same amount of infrared as the other objects in my room?

I got an infrared thermometer (SOVACARTE HS980E) recently and have been playing around with it. My understanding is that it works by measuring the amount of infrared radiation coming off of the object,...
Cloudyman's user avatar
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Why does my UV LED flashlight feel warm on my skin while my IR flashlight does not? [duplicate]

Both are 18 watts. Shouldn't IR feel warmer on my skin?
user3807846's user avatar
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Why does UV light feel warm on my skin? Whereas infrared light heats up space around me plus my skin?

Noticed something weird today. I have an infrared space heater that is pretty good at heating up my desk at work (as well as my skin obviously). I also have a UV flashlight. I noticed the UV ...
user3807846's user avatar
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What determines the particular frequency of infrared any given object emits?

Infrared (IR) includes EM waves between 780nm and 1mm in wavelength. (Source) As an object gets hotter, it emits a greater amplitude of infrared. What determines the particular frequency(s) of IR an ...
Oliver Walters's user avatar
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NIR laser reflection from metal surface

I am using 980 nm CW diode laser source as excitation source for fluorescence measurement. However, when I try to derive the dark spectrum before fluorescence measurement, I get two different kinds of ...
reckoner's user avatar
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Off-shell Photons and Collinear Divergences

I am reading Weinberg's book "The Quantum Theory of Fields", vol. 1. Weinberg suggests that the effect of radiative corrections involving $N$ soft photons is to multiply the (non-radiative) ...
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What is the temperature of a greenhouse gas?

The temperature of a gas is usually the sum of the kinetic energy of its particles, right? Whereas the temperature of a solid object is given by the Stefan-Bolzmann equation, as a function of how much ...
Karolina Hagegård's user avatar
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Absorption spectrum dependence on concentration/pressure

I am having difficulties understanding the relation between absorption spectrum and gas concentration. The online resources I found, including many questions here, do not clarify my doubts. Take for ...
Redirectk's user avatar
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Can there be any doubt that atmospheric "backradiation" is absorbed at the surface?

I am deliberately asking this question in Physics rather than Earth Sciences because I think it does come down to specific physical processes. The background is that I recently had a discussion where ...
Bob's user avatar
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How is black body radiation from sample eliminated when measuring absorption coefficient?

I wonder how absorption spectra of a sample (e.g. gas with some $CO_2$ absorbing strongly at $\approx 15\mu m$) is measured by IR spectroscopy, thereby having in mind the following arrangement, ...
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Can the receiver of an IR sensor pick up the signal from another IR sensor?

So I was trying to find a way to transmit a particular signal. I was thinking of getting one IR sensor to transmit a signal, which would be picked up by the receiver of another IR sensor. However, as ...
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Identifing a formula for the contribution of IR scattering to the permittivity of metals

I'm using a software modelling the complex refractive index of different materials in the THz/far infrared frequency range. One of the parameters that the user can add to the model of the permittivity ...
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What are some of the best materials to use for building a fiber laser safety enclosure of 1060nm - 1085nm?

I have gotten a 30W JPT-LP Litemarker Fiber Laser which has a wavelength range of 1060nm - 1085nm. Before even thinking about using it, i want to build an enclosure for it to increase the level of ...
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How can I get a 4.26µm wavelength light source with variable intensity?

I want to conduct a small home experiment involving ${\rm CO}_{2}$ particle detection. In order to do that I need a light source at $4.26$ $\mu$m wavelength (it's absorbed by ${\rm CO}_{2}$ molecules),...
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Understanding the Yennie-Frautschi-Suura (YFS) Infrared Exponentiation

I am trying to understand an alternative derivation of the Yennie-Frautschi-Suura (YFS) virtual photon exponentiation, given by Grammer and Yennie, in their paper "Improved treatment of the ...
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Why do dark objects absorb visible light but only emit infrared radiation?

What is it about the molecular structure of dark coloured objects that means they absorb most of the visible light that falls on them, but radiate infrared? Naively I would think that if a molecule ...
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Can the wall reflect infrared?

One day, I was sitting in my room and the fan in front of me was on. I was holding the control of the fan in my hand and facing the wall, I pressed its switch, and contrary to what I expected, the fan ...
Mahdi 's user avatar
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What are good materials to diffuse/scatter 850nm infrared light?

I want to properly light up a room with an IR Illuminator, but most illuminators lack diffusion, therefore shadows are especially sharp and bold. Since IR rays don't behave like visible light rays, it'...
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Decomposition of the Photon Propagator into $K$ and $G$ propagators

I am reading a paper by B. Sahoo and A. Sen, called "Classical and Quantum Results on Logarithmic Terms in the Soft Theorem in Four Dimensions". To determine the logarithmically divergent ...
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Is there any physical advantage in placing the sample between the recombined beam and the detector in Fourier Transform spectrometry?

Usually, in all the implementations of FT spectroscopy the sample is always placed between the recombined beam and the detector like in this figure from Wikipedia: Theoretically, the interferometer ...
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In what sense is the JWST image of Jupiter an improvement over prior telescopes?

JWST photographed Jupiter: The data includes images of Jupiter and images and spectra of several asteroids... The data demonstrates Webb’s to track solar system targets and produce images and spectra ...
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Can noble gases emit infrared?

So from my understanding infrared radiation can be emitted due to rotation and stretches in a intramolecular bond and by the emission of an electron from the Paschen Series. Considering noble gases ...
Caio Goncalves's user avatar
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316 views

Effect of changing $\rm CO_2$-levels on cooling the desert at night

It is known (e.g. as mentioned in this popular article) that the reason why deserts cool down at night so much (to temperature below zero degrees celsius) is that there is much less humidity in the ...
oliver's user avatar
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UV & IR radiation are mostly absorbed by water. Our eyes are predominantly water. If our eyes were made of another liquid, could we see slight UV/IR?

Firstly, I'm not a physics guy. I just think it's neat, that's all. I was reading a post on here about why water is transparent (I was more interested in why milk isn't) and saw a graph that showed ...
Jared Atkins's user avatar
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Question about field configurations on the boundary of $\mathcal{I}^+$

I am reading Strominger's lecture notes "The infrared structure of gravity and gauge theory" (https://arxiv.org/abs/1703.05448). In chapter two, while trying to derive an expression about ...
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Faddeev - Kulish paper questions

I have several questions regarding the paper Asymptotic conditions and infrared divergences in QED, written by Faddeev and Kulish in 1970. This is not a post about one question, but since all the ...
schris38's user avatar
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5 votes
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Virtual soft photon exponentiation

I have a question regarding Weinberg's soft exponentiation result in his 1965 paper called 'Infrared Photons and Gravitons' (https://doi.org/10.1103/PhysRev.140.B516). When he tries to calculate the ...
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