[Becca]

i am investigating the brewster angle of wet sand for a lab project and it would be really usefull if i had somethng to aim for as the refractive index so i'm researching the varying refractive indx of water over different wavelengths. i first really need it in infrared wavelengths but it would be good if anybody knew of a graph of the variation so i can see the whole range. i have searched the internet for hours now and the only sites that look usefull are the ones where you have to pay to read the journals. please help as i'm becoming increasingly frustrated with my fruitless searching.

becca

[eric l]

Hi Becca,

Using an other language with Google can be helpful. I tried in Dutch and got this for a second page :

Brekingsindex

The page also gives a link to a table with other refractive indices at different wavelengths.

Just to make things a bit easier, here are the values for water :

• 687 nm (red) : 1.330

• 589 nm (yellow) : 1.333

• 486 nm (blue) : 1.337

• 434 nm (violet) : 1.341

I'm sorry, the site does not list infra-red wavelengths. But water does absorb most of the IR.

[Becca]

wow, thanks, i never thought of searching in another language. how did you ever think to try that? also didn't you find that the pages were in dutch? oh well, thanks very much.

[max4236]

I found this graph of the Absorption Coefficent of Water vs. Wavelength, toward the bottom of the page on this website. It looks like it goes from the ultraviolet to infrared range:
Molecular vibration and absorption of water molecules

Maybe you could extrapolate the index of refraction from some sort of forumula like this. I'm not sure this would work for infrared frequencies though? It's just an appoximation.
What is the formula to find the absorption coefficients of materials?

X=(2Wnk)/c -> n=X(c/2Wk)

X=absorption coefficent
c=speed of light
W=frequency of light in the vacuum
k=attenuation index (also called extinction coefficient)

You'd think there'd be a graph of Refraction Index of Water vs. Wavelength out there somewhere..

[max4236]

Refractive index

"Fig 6. Segelstein's values for the complex refractive index of water for wavelengths from 10 nm to 10m"

[Becca]

there are a few graphs but they almost all stop at 700nm which i find quite selfish . that last one is great, thanks. you've all been a big help, i'll take it from here.

[eric l]

Originally Posted by Becca

wow, thanks, i never thought of searching in another language. how did you ever think to try that? also didn't you find that the pages were in dutch? oh well, thanks very much.

Well, Dutch is my mother tongue. If I want to check something on Wikipedia, I still start with the Dutch version. (By the way, Wiki is also a good way to find the key-word you need for searching Google in an other language : just type "refractive index" for the English article in your case, and next ask for the French, German, Spanish...)

I had planned to search in French andGerman, too, but the Dutch article gave enough information, the essential of which (the data) I translated. If you want a complete translation, it may take a little longer.

If you get no data for wavelengths above 700 nm, it is simply because most of the IR is absorbed by water !

[mpolyanskiy]

Hi!
Try RefractiveIndex.INFO. It contains refractive index of water for the range 0.182~1.129 microns

[johnfp]

Check out this site, it has usable calculators for such things.

HyperPhysics

[freeztar]

Originally Posted by johnfp

Check out this site, it has usable calculators for such things.

HyperPhysics

This link takes you directly to the calculator for Snell's Law:
Refraction of Light