Questions tagged [electromagnetic-radiation]

Electromagnetic radiation (EM radiation, EMR, or light) is a form of energy released by electromagnetic processes. In physics, all EMR is referred to as light, but colloquially light often refers exclusively to visible light, or collectively to visible, infrared, and ultraviolet light.

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31
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3answers
11k views

Are there non-transparent gases?

Are there gases that are not transparent at room temperature (i.e. at temperature below the point where the substance starts to radiate visible light due to heating)?
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5answers
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Microwaving a glass of water, what happens?

Most of us here would already know the simplified idea behind microwaving food: Microwave radiation hits the water molecules present in food, which excites them and causes 'em to vibrate rapidly in ...
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2answers
393 views

Why does a mixture of siloxene and cerium(IV) sulfate luminesce?

I performed an experiment where siloxene and cerium(IV) sulphate were mixed together: when I did so the mixture produced an orange-yellow glow. Why does it glow? What is it about the two chemicals in ...
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1answer
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Why is beryllium transparent to x-rays?

Beryllium has other fancy applications. It is transparent to x-rays, so it's used in the windows of x-ray tubes, which need to be strong enough to hold a perfect vacuum, yet thin enough to let the ...
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2answers
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Why does microwave heat up things so much more quickly than visible light?

I wonder why microwave has more "energy" to heat things up than visible light does. Microwave has a much longer wavelength, therefore should supposedly has less energy than visible light. But does ...
13
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1answer
683 views

Can reactions produce microwave or radio wave radiation?

I know that many reactions produce visible light, heat and sound, but is there a reaction (preferably one example for an inorganic and organic one) that could produce electromagnetic waves in the ...
13
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1answer
511 views

Radiation in space and its effects on chemical reactions?

I know that one current area of research is ways to protect astronauts from ionizing radiation when they venture out of the atmosphere of Earth, but would that same ionizing radiation be a cause of ...
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3answers
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In spectroscopy, is it possible for the sample to be excited multiple times?

The context of my question is rotational spectroscopy (using microwave radiation), where there is the $J = \pm 1$ selection rule. The way I understand spectroscopy is that the sample is irradiated ...
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2answers
341 views

Radiofrequency transmitter in an NMR experiment: Is there an involvement of (electromagnetic) radio wave?

A student in Chemistry StackExchange asked the effect of radio waves on matter, which led to an interesting set of arguments by some users. It was pointed out that in a proton nuclear magnetic ...
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3answers
794 views

What is the quantum mechanical explanation of X-ray diffraction?

One topic in crystallography that I've found a surprising dearth of information on is what the fundamental interaction behind the interaction of the X-ray and atom. Pretty much every book just treats ...
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4answers
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Is it safe to look at a mercury gas discharge tube? [closed]

As part of a chemistry course, I recently observed a demonstration in which the instructor electrified a mercury gas discharge tube (the tube looked something like this image). The glow from the tube ...
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Can gamma radiation cause transmutation?

In irradiation of food for sterilisation, is gamma radiation absorbed by the food? If so, can it theoretically cause production of radioisotopes? Or does it ionise atoms in the food?
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1answer
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Can one figure out an optical absorption spectrum from EPR data?

I'm wondering if it's worthwhile for me as an optical spectroscopist to read up a bit on EPR. Do EPR signals reveal where, in terms of wavelength, features in the optical spectrum can be expected to ...
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Can sunlight and its heat create a caustic or toxic substance from coconut oil on human skin? [closed]

I heard that story quite often, if it's true, how does it work? Notice that I’m not talking about using coconut oil as a sunscreen (it’s another topic) but about the action of the sun on the oil and ...
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1answer
277 views

Can gas be made to block radiation better?

Can any gas block radiation? I ask this because I would like to know if the properties of any gas element would chemically react differently with radiation from adding an electrical current. This ...
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1answer
4k views

Why can UV light initiate a reaction between hydrogen and chlorine gas?

Can someone explain me how does UV light help combine chloride gas and hydrogen to produce hydrochloric acid? $$\ce{Cl2(g) + H2(g) -> 2HCl(g)}$$
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1answer
285 views

What chemical properties that allow for colour exist in the dark?

Of course if there's no light around, there's no colour that you can see. On the other hand, the wall must have some property that makes it be blue. That property is still there in the dark. — Mike W. ...
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1answer
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How does radiation facilitate the formation of tetravalent iron?

In reading the article abstract What Oxidation State of Iron Determines the Amethyst Colour?, the author states that in regards to the gemstone amethyst, from clear quartz: The crystal was ...
5
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1answer
992 views

Are photons ejected from atomic nuclei?

I have heard that electrons absorb or eject photons when transitioning from one orbital to another. Is this correct? Can atomic nuclei eject photons?
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1answer
239 views

Wavelengths of the visible spectrum

Why is data about wavelengths of different colors and the visible spectrum in general so different in different sources? On Wikipedia, the numbers differ by up to $\pm\mathrm{30~nm}$.
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1answer
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Is there any difference between de-Broglie wavelength and the wavelength of normal waves?

Is de-Broglie wavelength different from wavelength of waves such as electromagnetic waves? If yes, they differ in what respect? And can we use the formula of wavelength of light ($c=v\lambda$) to ...
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De-excitation of a molecule

In our chemistry lecture today on UV/vis-spectroscopy, we discussed the origin of colour in conjugated molecules due to electronic transitions from lower-energy molecular orbitals to higher-energy ...
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3answers
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Stability of Bohr Orbits

In class we had been taught that Rutherford's model was unsuccessful because it failed to show that the orbits are stable because the electrons would lose energy because of electromagnetic radiation. ...
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0answers
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How much 'stronger' is water vapor than carbon dioxide, molecule-per-molecule, over the course of a day, in terms of global warming potential?

I have read, many times, that water molecules are far more effective than CO2 molecules at trapping heat... But, the 'relative G.W.P.' value of water vapor (or its 'radiative forcing') is not listed ...
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Does water really have strong EM absorption at 3 kHz in solid and 2 GHz in liquid? Why the huge shift?

While writing this answer to the question Transmitter receiver coil separation for Electromagnetic Terrain Conductivity Measurement I ran across this large PDF file of a book Soil and Environmental ...
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2answers
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How do IR spectrometers produce light spanning the entire infrared spectrum?

An IR spectrum covers thousands of wavenumbers, typically $\sim 4000$ to $\pu{400 cm-1}$. How are the spectrometers able to generate different wavelengths of light covering this entire range of ...
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2answers
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Transmission, absorption, and reflection of light

My understanding is: when light hits an object, it can do one of three things: transmit through the object, be absorbed into the object, or reflect from the object. However, I have also learned that ...
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2answers
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How do sunscreens protect the skin from UV rays?

I was unsure to the largest extent about whether I should post this question in chemistry Q & A or bio Q & A until I just read that sunscreens "absorb" UV rays, not allowing the most of those ...
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2answers
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How do I find mass equivalence of a photon?

The problem has a flame emitting a wavelength of $589\ \mathrm{nm}$, and asks for the mass of one photon of that wavelength. It tells me that $1\ \mathrm J = 1\ \frac{\mathrm{kg\cdot m^2}}{\mathrm s^2}...
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0answers
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Why do molecules showing a pure rotational spectra require a permanent dipole?

I understand that pure rotational spectra only exist for molecules which have a permanent dipole moment. The common explanation is "so that they can interact with the E-field of the incoming ...
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3answers
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Why does the photoelectric effect depend on the frequency of the light?

In experiments to detect the photoelectric effect, a clean metal was irradiated by monochromatic light and electrons were emitted. Why was monochromatic light used in the experiment, and why does the ...
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1answer
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What total energy (in kJ) is contained in 1.0 mol of photons, all with a frequency of 2.75 • 10¹⁴ Hz?

There is a question, that says: What total energy (in $\mathrm{kJ}$) is contained in $1.0~\mathrm{mol}$ of photons, all with a frequency of $2.75 \cdot 10^{14}~\mathrm{Hz}$? My answer was: The ...
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1answer
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Can visible light or infrared radiation excite electrons?

So the limit of ionizing radiation seems to be UV light. I'm wondering if IR light or Visible light can excite the electrons in an atom. It has to do with the difference in energy level right? So ...
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2answers
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How can I interpret the colour of flames in terms of spectral series?

I saw different colors of fire burning different metals. But how does this work? The Balmer series requires electrons to drop back down to n = 2. But, not all alkali metals have empty space in their ...
2
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1answer
280 views

Do different oxidation states of the same element have the same emission spectrum?

I looked at the flames of copper (I) chloride and of copper (II) chloride through a spectroscope and they looked the same. The flame colour is the same too. But since they have different oxidation ...
2
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1answer
40 views

Is there a relationship between loss of electrons and EM wave reflection? [closed]

Is there a relationship between the loss of electrons in a cation and the amount of electromagnetic spectrum, a compound of this cation would subsequently reflect or transmit? For example, any ...
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2answers
1k views

How do EM waves cause molecules to rotate, move, and cause electrons to move up energy levels?

Atoms can absorb electromagnetic waves to cause electrons to jump up energy levels, when electrons go down energy levels they release a photon. But how do EM waves cause atoms to rotate, and vibrate?
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1answer
134 views

Heat of reaction for the decomposition of AgCl means?

Certain sunglasses have small crystals of $\ce{AgCl}$ incorporated into the lenses, on exposure to light of appropriate wavelength produces a grey colour to reduce the glare following the reaction: $$\...
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1answer
28 views

About alternative magnetic effect on porcelain (for induction furnace purposes)

I am trying to use the Induction furnace mechanism (like described via this video), for heating part of the Muffle furnace, as one dental porcelain furnace prototype. So, my plan is to put copper coil ...
2
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1answer
160 views

Gamma spectrometry

I want to calculate minimum detectable activity (MDA) at 200 and 300 keV energy of a gamma spectrometry by HPGe detector. 662 keV Photopeak is present for 137Cs. Assume 2 scenarios: There is a 'peak'...
2
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1answer
157 views

Photoelectric effect and kinetic energy

According to my textbook, electrons which are emitted due to the photoelectric effect have kinetic energy given by: $$KE_{electron}=h\nu-h\nu_0$$ Where $\nu_0$ is the activation frequency of the metal....
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0answers
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Are the $+\leftrightarrow+$ and $-\leftrightarrow-$ methanol rotational transitions dipole-allowed?

I am quite confused about the origin and justification of the rotational selection rules of methanol, and I would appreciate any help or references. As far as I understand, there are three irreducible ...
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3answers
636 views

What are the effects of radio waves on matter?

Different regions of the electromagnetic spectrum interact differently with matter: Microwave radiation can induce molecular rotation. Infrared radiation can induce molecular vibration. Visible and ...
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1answer
77 views

Substances that pass visible light but absorb microwaves

Specifically, the substances should be water-miscible or water-soluble, but not water itself. Additionally, they should be absorptive but not opaque.
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1answer
78 views

When precessing nuclei absorb electromagnetic radiations, am I supposed to consider the wave nature or particle nature of light?

I decided to peek into the NMR section of my spectroscopy book, and I found out lots of interesting stuff. And along with the interesting stuff, I did come along some stuff that I didn't understand. ...
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1answer
90 views

Selective bond breaking

Can a specific bond be broken by an engineered energy wave corresponding to the bond length? For example, can we break the $\ce{C-N}$ bond and not the $\ce{C-H}$ in a hydrocarbon chain?
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1answer
566 views

What is the reason why protons and electrons do not collide?

can someone give me an intuitive picture of why electrons don't collide with protons? I know that electrons move in a sort of cloud, which is our 'orbital', and that they mainly behave like ...
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1answer
290 views

Is a microwave oven dangerous? [closed]

If we take a look at the electromagnetic specter, microwave wavelength is higher than infrared, which means its energy is very small. To break chemical bonds, the energy required is 100-1000 kJ/mol, ...
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1answer
243 views

How does UV affect skin colors in dark-skinned people?

Skin color is one of the things one would rather not ask anything about! Only in humans, it can vary from very dark brown to pale pink. In darker-skinned people, the color is mainly due to melanin, ...
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1answer
175 views

What emits the least radiation when hot?

What element with a high vapor point the emits to least light or radiation when heated to its vapor pressure point in a vacuum? Ideally I would like to know in 0 gravity and 0 pressure which ...