# Questions tagged [absorption]

A transition by which the energy of at least one photon is completely transferred to a material.

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### How linearly additive are the x-ray mass attenuation coefficients for molecules?

Having a look at https://www.nist.gov/pml/x-ray-mass-attenuation-coefficients, the introduction states: For compounds and mixtures, values for $μ/ρ$ can be obtained by simple additivity, i.e., ...
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### how to calculate the absorption spectrum for a given element?

I made a spectrometer that gives the absorption spectrum, by comparing the before and after readings. There are lots of information on the emission spectrum of elements, but I need the absorption ...
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### from a spectrometer, how to determine unknown substance in water?

I created a spectrometer that produces nice clean wavelengths, I calibrated it using a fluorescent bulb. from that I can create a graph from the data. after which, I use the known position to of ...
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### How does silver affect transmission of energy in the visible and infrared part of the spectrum?

A common method to prevent radio frequency and microwave energy from going through windows is to apply a microscopic layer of silver to the surface of the glass, either by attaching a film coated with ...
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### Cause and description of 'secondary' probability peaks in Above Threshold Ionization

While reading about above-threshold ionization, I found this graph on the wikipedia page about ATI: The $x$ axis represents the kinetic energy of the electron and the $y$ axis shows the ...
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### given an AC field, how many photons are there?

Say you are applying a time varying potential across double quantum dots in the form of $V_{ac}$cos($2\pi f t$). We know that each photon has an energy $E_{photon}= hf$. Is it correct to say that ...
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### White hotter than black

Black color substance is assumed to absorb all the light/radiation that falls on it. White color substance on the other hand, reflects all the radiation that falls on it. Since all the momentum of ...
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### Do objects reflect light of their own color based off constructive wave interference?

Note: Why objects reflect light of their color is already answered here: Physics of color: why do visible colors absorb all colors except the color itself? My question is whether my following theory ...
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### What are some mechanisms that can lead to unexpected/anomalous spectral lines

I am studying fluorescent spectroscopy (laser-induced fluorescence spectroscopy specifically). In a particular atomic spectrum, there are some unexpected lines not associated with any known ...
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### Does photon absorption annihilate the associated EM wave instantly?

My Understanding A single photon has an associated electromagnetic wave. The wave is spread out in space, but the photon is considered a point particle. If the photon is absorbed, the entire wave ...
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### Partial absortion of a photon

In atoms, there are electronic energy levels, when there is a match between those and a light photon energy, an electronic transition ocurs. Example and question Suppose an atom has a levels $0$, $1$...
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### How do you calculate the recession velocity?

\begin{alignat}{7} && \frac{\Delta \lambda}{\lambda} & = \frac{v}{c} \\[2.5px] &\therefore & v & \approx \frac{\Delta \lambda}{\lambda}c \end{alignat} If you want to find ...
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### Why walls are blocking infrared waves? If bricks absorbs only certain infrared frequency as shown in the infrared absorption spectroscopy graph below

link to the pdf I am told that infrared is reflected(blocked) by wall. my argument is,how can they reflect a photon if they don't absorb it.as you know infrared is absorbed by molecule which has same ...
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### Optical conductivity: Does higher real part mean higher losses/absorption?

My question is with regards to the relationship between optical conductivity and optical permittivity. Since the imaginary part of optical permittivity signifies losses/absorption, the real part of ...
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### The Attenuation of Light

I have this question: Show that the attenuation of light as it travels through the interstellar medium follows an exponential law My initial thoughts were to demonstrate the absorption of ...
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### Hypothetically, if there was a substance that could absorb all visible light and reflected none, how would it appear to the human eye?

Would said substance just be perceived as a "hole" in our vision, if it was capable of absorbing 100% of all light? Also on a side note, would the absorption of all light instead of only visible ...
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### Complex part of second-order susceptibility in nonlinear optics

In optics, the absorption of photons by a material can be described by considering the material's susceptibility. For linear absorption (involving a single photon), we think about the imaginary part ...
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### Cosmic ray shielding for electronics on Earth

There are plenty of topics discussing cosmic ray shielding, but they all put emphasis on spacecraft shielding, where things like radiation and mass are a big problem. So I decided to ask a question ...
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### Is infrared radiation more easily absorbed than visible light?

Some background: I am curious if infrared lamps used in hatcheries and bathroom fixtures offer any advantage over ordinary incandescent bulbs. A 40 watt bulb produces the same amount of energy, ...
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### Measuring the heat absorbed by objects close to a radiator

I have a digital piano 12"/30cm to the side of a radiator (not in front of it). Radiator is 60°C as measured on an infrared (IR) thermometer, air temperature around the piano is 16-17C with the ...
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### Why are some materials dull rather than shiny (cloth, coal, matte paint etc.)?

The converse of this question is perhaps "why are metals shiny". From what I understand, metals are covered by a sea of free electrons that oscillate in response to incident light/EM wave, and the ...
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### Emission and Absorption in color

This may be a really simple question: If electrons only absorb specific wavelengths of light and then emit them and that’s how we see color, but what happens to the other wavelengths? Without them ...
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### What happens when we supply heat to a collection of atoms?

When we heat a collection of atoms, we supply energy to the electrons of the atoms. When the energy equals the minimum energy required for the first transition of the electron the electron absorbs ...
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### What happens in the case that the incident light on an atom has photons with insufficient energies to excite an electron?

When an atom of an element is irradiated with a monochromatic light, what will happen in the case that the frequency of the light does not match the frequency needed for any of the several possible ...
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### Why light cannot pass through wall whereas Sound can? [duplicate]

I have read answers stating that light is not able to be transmitted through a wall whereas sound is easily transmitted due to difference in wavelength. But, why? I am looking for detailed and ...
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### Are Emission and Absobtion spectrum EXACT photographic negative for Hydrogen Sample?

If both are exact photographic negative, then is it true that the way an electron can deexcite (for eg.4$\to$1) in many ways like first 4$\to$3 and then 3$\to$1; absorption can too take place in ...
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### How to convert RF absorption rate (SAR) values to electric field values?

I'm currently reading a bunch of journal articles that describe biological effects of electromagnetic fields. They often refer to the field in terms of specific absorption rate (SAR) values (W/kg). ...
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### Temperature profile of the atmosphere due to absorption by a gas

I want to observe the temperature profile of the atmosphere due to absorption by a gas such as water vapor. I know that optical thickness changes as the density of the gas changes with altitude in the ...
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### The best range to measure the differences between glass, can and plastic

First of all, i'm Computer science student, so maybe the question is simple for this forum so i'm apologize and hope that i will found help here I working on recycle bin which automatically ...
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### How can we classically describe the formation of absorption spectra?

When dealing with the problem that femtosecond laser pulses interact with atoms, the semi-classical method is usually used: we describe the atom as quantized and describe the pulse classically. I ...
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### Are changes in light aborption induced by changes in medium concentration multiplicative with light intensity?

I'm working in the area of near-infrared spectroscopy where we shine light through tissue and measure the attenuation at a detector nearby. The detector is actually placed on the same surface as the ...
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### Reflection, emission and absorption of light

When you shine a light on an object, some of it gets reflected and the rest gets absorbed. $A + r = 1$ Where r is the amount of light reflected per sec in $1m^2$ and A is the amount of light absorbed ...
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### Can light travel through solid substances such as wood?

Today as I was doing my science, I came across this statement: "In essence, then, the Special Theory of Relativity says that the speed of light is the ultimate speed limit because nothing can ...
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### Over cooking of baking [closed]

Why does a black pan get hotter than a lighter pan in a dark oven? Everything I've read says that it is the visible light that causes the increased absorption of heat.
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### How do we detect infinitely narrow emission / absorption lines within continuous electromagnetic spectra?

This always bothered me, especially in the case of absorption lines. for instance, if you have a blackbody emitting a continuous spectrum, and then a filter in front that only filters out one very ...
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### Why does the sun/moon appear red when there are fires?

Recently, in the United States, the moon and sun have become very deep red when they are near the horizon. The reason given for this is that there have been extensive wild fires in the Northwest. So, ...
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### Bethe Bloch Plot

Why is the stopping power in Bethe Bloch-Plot shown against $\beta\gamma$ on the horizontal axis? Respectively what is the meaning of $\beta \gamma$? Plot taken from here
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### Electronic transitions in potassium

Potassium atoms in the electronic ground state absorb laser light at 769.9, 766.5, 404.7, 404.4, 344.7 and 344.6 nm. Obviously, these absorption lines exist because an electron is excited from the ...
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### Are these statements about different emissivities correct?

I'd like to verify if my concluded statements regarding different emissivities are correct or not. And if not, why. 1 Two objects, one with an emissivity of 1 (object A) and one with a very low ...
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### Integrated absorption coefficient

The absorption coefficient is usually defined as $$\alpha(\nu)=\frac{1}{d}\ln\frac{I_0(\nu)}{I(\nu)},$$ where $d$ is the thickness of the sample, $\nu$ is the light frequency, and $I_0$ and $I$ are ...
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### Why does a yellow object turn white under a yellow light? Shouldn't it turn yellow instead?

Recently I was eating a yellow rice for lunch in a restaurant with only yellow lights. But the rice looked white! I was intrigued by this because I always thought it should look yellow since the ...
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### How does the reflectivity of a light-source change when it's switched on/off?

Q: How does the reflectivity of a light-source change when it is switched on/off? Consider a light-source like an red LED with some white light shining on it. When the LED's switched off, it's going ...
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### Why do colours of object change due to incident light?

A leaf is green, a pen is blue and so on because those objects absorb all colours and reflect only one colour. However when red light is incident on these objects, their colour becomes reddish. Why is ...