X-Ray Diffusion

They'd work, but they would be different due to the difference in frequency.

Look at prisims and refelctive signs.

"Does this same principle apply to higher-energy optics, such as x-rays?"

Ionizing radiation doesn't reflect.

Sorry, but you are incorrect. Xrays do reflect, they also diffract. There are also xray diffusers. Xray reflection is used to examine substances for their content. A common handheld device is used by many recyclers to determine what metals they are dealing with, including alloys. This device uses xray reflection. Xray diffusion is achieved in several ways, the most common way is a glass "lens" that has finely ground mica mixed into it. Diffraction is achieved by ferrite sheets assembled in a variety of configurations very similar to those used for light. Xrays, in fact display most of the same properties as visible light. Except of course that they respond quite differently to whatever is paced in their path due to the much shorter wavelengths. And of course they also respond to both magnetic and static fields. I'm currently working on resonant cavities that are used to produce and control high energy plasmas. One of my biggest problems is suppressing and controlling the Xrays that are produced!

The example that you gave is not correct. The devices you describe for checking metal is based on X-Ray Fluorescence, which I don't think anybody would lump in with reflectance. Yes, "light" is returned, but it is of different wavelengths than the incoming X-rays.

There are X-ray "reflectors", but it's quite a bit more complicated than visible light.

Please Google this subject. There are too many citations for me to refer here. If your interpretation of reflectance denies change in wavelength, then there is no such thing as reflectance at all! All reflection encompass "some" change in the incident returned beam. If you shine "white" light on "red" object you get a return of everything except the red wavelengths that are absorbed by the object. Look up xray reflection on Wikipedia, there are several good articles. Reflection is implied simply by the geometry of the source and termination of the energy directed at a surface, changes due to absorbance or wavelength shift are not only allowed, thru are expected! The device in question does "not" work by xray fluorescence, it works by analyzing the wavelength and strength of the returned energy. Basically, it's a simplified form of xray crystallography. That's why the device is able to determine even the steel quality of it's sample.

If you shine "white" light on "red" object you get a return of everything except the red wavelengths that are absorbed by the object.

Don't you have that backwards? I thought that the stuff we call "red" is stuff, which absorbed everything but the "red" wavelengths of the light.

That is a common misconception. Human eyes "see" a red object when the "red" portion of the spectrum is reduced or eliminated from white light. This is why we use "blocking" filters on photographic equipment. If you take a white light and put a red filter in front of it all the light looks red does it not? The red gel removes the red spectrum from the white light.

Bollocks.

I don't speak limey. What does "bollocks" mean in American English?

He's not a limey. It means hogwash, poppycock, bullcrap.

"Limey?" You mean British English? They are not 'Limeys,' they are British and there are a lot of them here, on this forum. Decent folks, too, and friends. You owe them an apology, mister.

Bollocks = balls, testicles, gonads, etc.

Has several uses: a general expletive, slang for "rubbish," "nonsense," "I disagree" etc.

'Nuff said.

This backwards from what happens. When a human sees red, all other wavelengths other than red have been eliminated.

A lasers emitting essentially one wavelength anywhere between 620 and 740 nm will appear red...not almost every other color except red.

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We see red as red. Not everything but red as red.

That is a common misconception.

Well, I guess so! It is so COMMON, that I can't find a single reference to anything that supports your position! Can you?

The rods, and cones in our retinas, react to specific wavelengths of light that strike them. IF, as you claim, the red wavelength is absorbed by an object, and all BUT the red wavelength is reflected, then the red wavelength would not find its way to our retina, to be interpreted as red by our brain.

Assuming that you are not pulling our collective leg(s?), then apparently you honestly believe this, because someone taught it to you that way. Where, and what documentation was used to deceive you? What was this teacher's name, and is he, she or it still teaching? If so, they need to be stopped.

Something whichs absorbs a certain frequency is also able to emit at that same frequency.

This applies to antennas but I wonder if it also applies for color?

Light is electromagnetic radiation, whether visible or invisible its all light.

Hadn't really applied that analogy to this situation in my mind. Although, it occurs to me, that might not be a universal trait, and axiomatically applicable to all things. In fact, there is a whole industry of stealth coating materials dedicated to NOT exhibiting that particular property for as many frequencies as possible.

But, as specifically applied to perceived color, not all things derive their appearance completely from reflected light. Somethings have a combination of reflection, and refraction, and I guess now I can include retransmitted light. The question then becomes, how much of each is applicable to any specific thing?

I'm sorry, DogofWar, but you are incorrect on most points. I would Google a bit more if I were you.

Look up X-Ray Fluorescence (XRF) and X-Ray diffraction (XRD). I am a chemist and have worked with both.

XRF is used to determine elemental content, and is used in the hand held devices that you speak of. XRD is used to determine crystal structure.

Elements cannot be determined by XRD. Metals are not very crystalline (usually). There are no held held XRD devices.

Mirrors reflect light at the same wavelength as the incoming beam.

Wavelength shift is not present in reflectance. If the wavelength changes, some other process has occurred, such as fluorescence. If an object is not "white", it absorbs some wavelengths, but not others. It does not shift any wavelengths.

If lights reflects off of a moving mirror it should experience some frequency shift.

If the mirror is moving away from you it will be a red shift.

So simple reflection can cause frequency shift.

Or am I missing something?

What if the light is moving with the mirror

1) and so is the observer,

2) but the observer is not.

Redshift is not an attribute of reflection but of relative motion between the source of the light and the observer, however realised.

Really? How do the x-rays get emitted unless they reflect off the electrode?

I do not believe there is an equivalent diffusing material for X-rays. As there are translucent materials for visible light. The scattering effect with visible light happens from a collection of application of Snell's Law in the irregular polycrystalline structure and the absorption and retransmission of the light. In contrast the nominal atomic spacing of a solid is tens of nanometers. The wavelength of an X-ray is ten nanometers and smaller. So the scale sizing of X-ray wavelength will likely not interact with any solid material in a diffusing fashion.

I do know that X-rays are focused using bent silicon crystal structures at only critical angles that involves also appropriate crystal alignment.

Crystal structure is the essential element in xray reflection. Mica works as an excellent diffuser of xray energy. In another subject related area; scientists and engineers tend to have very different viewpoints on some things. This is because engineers generally user a very narrow definition specific to an application, and use models that are simplified to fit the specific application to a solution. Scientists are more likely to use very detailed and comprehensive methods and models. It doesn't mean that either is wrong, but you wouldn't want to use scientific methods to do engineering or vice versa. The biggest problem is that many engineers assume that traditional understandings are correct when they often are not. Perception and reality are NOT the same thing!

You clearly know nothing of any substance concerning Human vision, not even where it concerns plain, ordinary common sense and simple observation, so why should anyone here afford your broad, bigoted generalizations of people any credence? You've only succeeded in broadcasting your vast ignorance and aversion to knowledge to a largely international audience: "Look, another ignorant American!" Thanks a bunch, pal, you're a real credit to your country.

Another spirited "discussion".

I was trained as a "scientist", but worked as an engineer.

Engineering is the reduction of scientific principal to practical application.

My experience in engineering is different than you describe. When a scientist says that something is not possible (but must be done for practical purposes), it is the engineer that looks for the unseen exception to the scientific "rule".

A male scientist and a male engineer are facing two beautiful women, about 10 feet away. They are told that they can have their way with the women if they can reach them, but they can only jump half the distance between them and the women with each move. The engineer starts hopping right away. The scientist doesn't move and says "you damn fool, you will never reach her". The engineer replies, "true, but I can get close enough for all practical purposes"

Sorry if this offends anyone for any reason,

What of Bragg reflection from polycrystalline microfacets? The effect is nearly the same as with visible light reflecting from colloidal crystals. Both are diffuse reflectors which depend on the same principle: Bragg reflection. In the case of colloidal crystals, the sphere spacing is comparable to the wavelengths reflected; sort of a macro-scale version of reflections from a crystal lattice at X-ray wavelengths. If you've got lots of these all jumbled up at microscopic scales, you've got a pretty efficient X-ray diffuser.

The OP did not mention whether or not the X-ray source is monochromatic, but as with all monochromatic sources, if you could see in X-ray 'light' the result of diffusing the X-rays will be a mottled, grainy pattern. You've seen this with laser light. Set up a laser pointer to shine on a diffuse surface, preferably one that's translucent (glycerine soap makes an excellent diffuser for the purpose). If you set the laser up in a stationary configuration and hold very still, you'll see a grainy, mottled pattern. Essentially the same thing except for a change of scale. (You can tell whether a person is near- or far-sighted, moreover, by noting which direction they see the mottled pattern 'move' when they move their head slightly; the pattern either moves with the motion of their head or against it.)

I've been avoiding replying to this thread because it has been fun seeing the variety of accurate answers that show how X-ray diffusion can be achieved. They also clearly show that I focused way too much on my understanding of translucence.

I didn't state this before, but why would a diffused X-ray source be desired? Uniformly illuminating a laptop screen with X-ray light makes no sense to me.

The backlight behind an LCD uses a combination of reflection, refraction and scattering. The light cavity or plastic wedge reflects light around, the diffuser layer uses refraction and scattering, and a layer or two of microprisms refracts the light toward the viewer.

X-rays are diffracted, and are often used in crystallography and for studying materials. Here's an image of X-ray diffraction through some Martian Soil:

Scattering is a form of reflection; for example the scattering of light off particles in the atmosphere depends on the relative size (wavelength) of the photon and size of the molecule doing the scattering. Scattering is what makes the sky blue. Short wavelengths (blues) are easily scattered (reflected sideways or at high angles), red light is not. Which is why sunsets look red.

Images from Wikipedia.

Someone once told me that diamonds are practically invisible on X-Rays because the crystalline structure was in such alignment that the beam is not diffused, or attenuated by absorption. Can anyone else here confirm this?

Yes, if they are perfect. That's rare for even diamonds.

For your own protection, I suggest that you send me all your diamonds immediately. I'll test them free of charge and send them back to you.

Absolutely correct. X-rays are used to examine the chemistry and physics that happens in a diamond anvil.

Diamond mines identify raw diamonds in crushed ore by means of X-ray fluorescence. A blast of air directed at the diamonds separates them into bins for later sorting. In earlier times a greased conveyer belt was used to separate diamonds by taking advantage of diamond's affinity for hydrocarbons. They'd bind to the greased conveyor more tightly than the ore which was then washed away with a water spray.

Rio Tinto's Argyle Diamond mine in N. Australia uses X-ray fluorescence to spot diamonds in the ore. The process is completely automated and it must work because the Argyle mine (the world's foremost source of exceedingly rare pink diamonds) produces around 32 million carats of rough diamonds per year. Most of these are brown-to-black in color and find their way to industrial applications. Of these 32 million carats, roughly 100 carats are gem-quality diamonds. One of the world's largest pink diamonds was found there last year, the 8.01-carat Argyle Pink Jubilee:

Here it is in the rough:

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I modeled the APJ cut as a 4.1-carat round brilliant:

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Models of two other Argyle Pinks.

This link provides a basic understanding of x-ray diffraction and it's uses.....

http://www.geosci.ipfw.edu/XRD/techniqueinformation.html

Suggest you check out "grazing angle" diffraction for x-rays. X-rays can be focussed by specially shaped mirrors and tapered tubes. Take a look at the following:

Damn it! What has happened to the "copy and past" function on CR4 ?!

Use Cntl+c and Cntl+V for copy and paste...

OK - here goes:

http://www.xradia.com/technology/basic-technology/focusing.php

Success! Thanks!

So diffraction and reflection won't work, but what about refraction? What if there was something like salt crystal that changed the direction of the rays as they went through?Snell's law sort of thing.

Interestingly, Physicists have found a way to refract gamma rays, though a technique that works well for the wavelength band of X-rays remains elusive.

http://physicsworld.com/cws/article/news/2012/may/09/silicon-prism-bends-gamma-rays

http://www.photonics.com/Article.aspx?AID=50816

These articles both imply that the methods used to refract X-rays are poor and that the amount of refraction is so weak that the rays are almost completely absorbed by the time any significant refraction occurs. However, I did find a patent for a device that refracts X-rays, though I haven't taken the time to read it or see if there are any diagrams. If you're interested it's:

http://www.google.com/patents/US20060256919

'...Physicists have found a way to refract gamma rays, though a technique that works well for the wavelength band of X-rays remains elusive.....'

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The distinction between gamma rays and x rays is that gamma rays originate from the nucleus while x rays originate from electrons outside the nucleus.

Don't the range of wavelengths of gamma rays completely overlap the range of wavelengths of x rays? It would seem to make the above statement difficult to understand.....

X-rays and and Gamma rays do have an overlapping band in the 10 to 1 picometers wavelength range but most of their spectrum do not overlap. Your "rule of thumb" of each ionizing radiation source seems reasonable for most terrestrial conditions. I would expect that an astrophysicist would know of several exceptions.

The link you provided says x-rays have wavelengths of 10 picometers to 10 nanometers.

There are certainly gammas from radioactive decay of unstable isotopes with energies lower, higher and within that range.

As long as we agree that X-rays have wavelengths from 0.01 to 10 nanometers and that any EM radiation that originates from the nucleus is called a gamma ray, I don't see how there can reasonably be exceptions to the statement that the range of gamma rays overlaps entirely the range of x-rays.

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So the original assertion about something being able to be done with gamma-rays but not with x-rays, is almost certainly referring to a very specific range which does not include x-rays....and I suspect it is for shorter wavelengths than x-rays, I'm just curious.

You are correct in that there is an "overlap" of x-ray and gamma rays. After all, it's an entirely man-made decision where the x-ray region and gamma ray region start and stop. They are both photons and electromagnetic radiation at the same time. As you say, gamma rays originate from the nucleus while x-rays originate from the electron orbitals. An example that may confuse people is the emissions from the Am-241 isotope. It emits a gamma ray at 26.3 keV but an x-ray at 59.8 keV. In other words the gamma is less energetic (longer wavelength) than the x-ray. The distinction is based on where the photon originates - nucleus or electron orbitals.

An amusing example of terminology occured some years back in the semiconductor industry. In order to get improved definition of microchip circuits via photolithography, the industry switched to much shorter wavelengths, which would normally be regarded as "soft x-rays." But to avoid all the rules and regulations associated with the use of x-rays, they called it "extreme ultra-violet" - and got away with it. Who's to say where one stops and the other starts?

X-ray optics depend on refraction, reflection and interference. Diffraction and reflection do work.

Your thread title reads "X-Ray Diffusion" What do you mean by X-ray Diffusion? Perfumes diffuse through the air. Don't you mean diffraction?

Please clarify.

Note: I mean diffusion and not diffraction.

I'm wondering if x-rays diffuse in the same manner as visible light.

Thanks for clarifying. Yes, they do, but if you have control over the X-ray source, it is more efficent and easier to create a diffuse X-ray emitter by stimulating bulk emission in a suitable material. A spray of electrons directed at a wad of tungsten wool. If your electrons have a broad energy spread your X-rays will tend to be less monochromatic, much as is white light. Monochromatic X-rays tend to produce the same 'speckled' self-interference patterns as monochromatic laser light, just at a much smaller scale commensurate with wavelength.