Gold's absorbance of blue light

In summary, the conversation discusses the possibility of using a polished gold foil surface of 1 cm2 to absorb 1 watt of light with a strong spectral peak around 470nm. It is mentioned that gold can absorb around 62% of this light, but it will also reflect longer wavelengths. The speaker suggests using other options, such as color glasses or multilayered filters, for more accurate filtering of specific wavelengths. The conversation also mentions the possibility of overheating the foil and the fact that the amount of light absorption depends on the power of the light source.
  • #1
Martwilk
1
0
TL;DR Summary
How many watts of <500nm light can 1 square centimeter of gold foil absorb? Is there a limit?
I have a LED light, which has a strong spectral peak around 470nm, and a broad emission spectrum in the deep red and infrared. I want to block most of the blue peak, and gold will absorb around 62% of this blue light. Will a polished gold foil surface of 1 cm2 be able to absorb 1 watt of this light?
And out of curiosity; is there a limit to this? Will it be able to absorb 100 watts of this light? Thanks!
 
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  • #2
At some point the foil will overheat. Apart from that: No.
 
  • #3
Won’t most of the light be reflected?
 
  • #4
I'm surprised but apparently not:

https://www.researchgate.net/figure/Reflectance-curves-of-silver-Ag-gold-Au-and-aluminium-Al-For-optical-coating-By_fig1_233814472
 
  • #5
It depends on the thickness of the gold foil. If you have a thin film of gold (say a few nm thick), it will appear green (by transmission). For silver, this would be more blue. When the thickness is macroscopic one loses almost entirely the transmission, of course.

Will a polished gold foil surface of 1 cm2 be able to absorb 1 watt of this light?
.
If you polish the surface, you will increase its reflectance, thereby reducing light absorption. What's more, the "1 W" that you quote, entirely depends on the power of the source, or the incident light's power. It certainly is possible, given a strong enough light source, but I guess the light source is not something tweakable?
 
  • #6
While gold is most absorbing in the blue to green, a thin foil will also be most transparent in this region. In the reddish part of the spectrum, almost all of the light will be reflected.
 
  • #7
Martwilk said:
Summary: How many watts of <500nm light can 1 square centimeter of gold foil absorb? Is there a limit?

I want to block most of the blue peak, and gold will absorb around 62% of this blue light.
And what do you want to do with the remaining light?
It seems to me that you want to filter out blue light and transmit the rest. Using gold isn't a good idea; it will absorb blue light but reflect longer wavelengths, i.e. red, orange, green.
There are other options available: color glasses which have a specific transmission curves, for more accurate filtering there multilayered filters. They are specifically designed to provide rejection of some light while transmitting another.
 

What is the relationship between gold and blue light?

Gold has a unique property of absorbing blue light. This means that when blue light is shone on gold, the gold will absorb the blue light and appear to be a yellowish color.

Why does gold absorb blue light?

Gold absorbs blue light due to its electronic structure. The electrons in gold are arranged in such a way that they are able to absorb the energy from blue light, causing them to vibrate and emit a yellowish color.

How does the absorption of blue light affect the appearance of gold?

The absorption of blue light gives gold its characteristic yellowish color. Without this property, gold would appear to be a silvery color like other metals.

Can gold absorb light of other colors?

Yes, gold can absorb light of other colors as well. However, it has a higher affinity for blue light, which is why it appears to have a yellowish color in most cases.

Is the absorption of blue light by gold useful in any way?

Yes, the absorption of blue light by gold is useful in various applications, such as in photography, where gold is used as a filter to remove blue light. It is also used in the production of yellow-colored glass and ceramics.

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