3 ms·
Back-of-the-napkin: > 90-nm ultra-thin I don't know the density, but let's say 2g/cm³. That means a 1cm² piece of this film weighs 18 micrograms. > 30°C to 1
by skosch 8y ago
Back-of-the-napkin:
> 90-nm ultra-thin
I don't know the density, but let's say 2g/cm³. That means a 1cm² piece of this film weighs 18 micrograms.
> 30°C to 150°C in 30 seconds
If by "sunlight" they mean 1000 W/m², which is generous, then our 1×1 piece would catch 0.1 W. Over 30 seconds, that makes 3 joules.
3 joules to heat 18 micrograms by 120 degrees – that's a specific heat capacity of 1.388 joules per gram and K (a bit more if the density is lower than 2, a bit less if it's higher). So: a bit more than typical metals, probably, but not by much.
- DEADBEEFC0FFEE 8y agoThanks, why can't this type of information be included in the article. A comparison with a common material would be useful to ok. Like copper or something.
- gotocake 8y agoYou’re a champion, thanks!
- nardi 8y agoCould you explain why the specific heat capacity is the important metric? It seems like the rate of absorption would be more important. (In other words, the percentage of incident photons absorbed.)
- skosch 8y agoI just wanted to answer the question. The limiting factor is indeed the sunlight and how much of it is absorbed – thus my comment that 85% is nothing special.