"Bending" X-rays

[tinkerer]

My Physics text in High School contained the following statement, as closely as I can recall it:

"X-rays may be bent and diffracted by means similar to visible light".

I asked our instructor, if x-rays pass freely through a glass prism, how can the text's statement be valid?

He was a recent college grad., his academic background unknown. He kind of shrugged, and as he usually answered the "unanswerable" said, "Read the book!"

 

[mathematic]

Because X-rays are much shorter in wavelength than visible light, different materials are needed.

[swansont]

X-ray diffraction is used to determine molecular structure, so clearly they can diffract.

[mistermack]

On 11/11/2018 at 10:42 PM, tinkerer said:

if x-rays pass freely through a glass prism

Is that right? According to this they get refracted :       http://www.x-ray-optics.de/index.php/en/physics/refraction  

Interestingly, according to that page, X rays are refracted in the opposite direction to visible light. So focusing lenses for X rays would spread optical light. 

I'm a bit mystified by that, as visible light refracts more as the wavelength gets shorter, so I expected X rays to follow that pattern. But logically it would mean that there must be a certain wavelength in the ultraviolet that gets zero refraction by glass.   

[swansont]

2 hours ago, mistermack said:

Is that right? According to this they get refracted :       http://www.x-ray-optics.de/index.php/en/physics/refraction  

Interestingly, according to that page, X rays are refracted in the opposite direction to visible light. So focusing lenses for X rays would spread optical light. 

I'm a bit mystified by that, as visible light refracts more as the wavelength gets shorter, so I expected X rays to follow that pattern. But logically it would mean that there must be a certain wavelength in the ultraviolet that gets zero refraction by glass.   

It has to do with the fact that for x-rays, the electrons in atoms look like free electrons (since the photon energy >> ionization energy) and the index for an electron gas is <1

[tinkerer]

Of course, the young mind of a 15 year old then more interested in cars and engines than Physics, might not be expected to "see through" the author's simplified statement. Seems pretty evident that a glass prism, say, "breaks up" white light based on it's wavelength, red thus being bent more than violet, as the whole mess passes through. Thus, X-rays, being "light" of a much shorter wavelength than visible violet light, would be bent only a minute amount, detectable, perhaps easily now, less easily in 1950. 

Since we're on Physics, long ago I came across the following sequence of high-speed X-ray exposures taken microseconds apart, supposedly released many years after they were produced at Los Alamos, showing quite graphically and vividly, the compression of an "incompressible" solid when enormous pressure was exerted from all around the test sample:

[Enthalpy]

The index of most materials increases with the energy of visible photons, but above some threshold that X-rays vastly exceed, photons ionize matter and other laws apply. Refraction needs electrons to be little disturbed by light, but X-rays use to ionize.

So "means similar to visible light" is bold. Check the XMM satellite for instance, and what kind of unreasonable "optics" it needed to make X-rays pictures.