Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: scientizscht on 11/02/2019 21:15:30

Title: What are substances or reactions that generate UV rays?
Post by: scientizscht on 11/02/2019 21:15:30
What are substances or reactions that generate UV rays?
Title: Re: What are substances or reactions that generate UV rays?
Post by: alancalverd on 11/02/2019 22:41:32
The most common source of controllable ultraviolet is a mercury vapor discharge lamp. Looks just like a fluorescent tube but without the fluorescent inner coating, and preferably with a quartz envelope. Cheap and very effective.
Title: Re: What are substances or reactions that generate UV rays?
Post by: chiralSPO on 12/02/2019 01:43:43
What are substances or reactions that generate UV rays?
Can you be more specific? There is a very wide range of wavelengths considered UV. Are you interested in emission that is narrow, wide, only UV, includes UV, coherent, polarized?

Bright line spectra of many elements include several UV lines
there are UV diodes (like leds for uv)
UV lasers (excimer lasers are some of the most powerful UV lasers)
many organic molecules and some inorganic nanoparticles will fluoresce in the UV, when excited with an even shorter wavelength
blackbody radiators will produce UV radiation when sufficiently hot (>2000 C)
etc. etc.
Title: Re: What are substances or reactions that generate UV rays?
Post by: evan_au on 12/02/2019 10:14:34
High-voltage discharges (eg from an arc welder) can reach temperatures in excess of 10,000 C, and will cause severe sunburn (UV burns) to unprotected skin and eyes.

The latest generation of high-speed CPU chips (with 7nm features) need high-intensity UV light with a narrow range of wavelengths. Commercial machines use powerful lasers to blast tiny particles of tin into a plasma, which then produces a burst of Extreme UV light (EUV).

See: https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithography#Light_source_power,_throughput,_and_uptime
Title: Re: What are substances or reactions that generate UV rays?
Post by: scientizscht on 12/02/2019 17:37:21
Substances or reactions that generate any kind of light at normal conditions?

Not having to zap them with 10 million volts or burn them at 3000C.

Title: Re: What are substances or reactions that generate UV rays?
Post by: Bored chemist on 12/02/2019 17:57:21
There are many reactions that give out light
https://en.wikipedia.org/wiki/Chemiluminescence
It's relatively unusual for them to give out UV because not many chemical reactions are that energetic.
It's not impossible
https://www.sciencedirect.com/science/article/abs/pii/0009261487805043
but many materials that carry enough energy to emit UV will react with water (or other solvents) so the reactions that generate UV are typically gas phase reactions.
Title: Re: What are substances or reactions that generate UV rays?
Post by: chiralSPO on 12/02/2019 18:42:12
Substances or reactions that generate any kind of light at normal conditions?

Not having to zap them with 10 million volts or burn them at 3000C.



Gotta put energy in to get energy out...

Diodes require >3 V to produce UV (3 eV is a lot of energy for a photon, but that's why UV light can be so damaging)
Title: Re: What are substances or reactions that generate UV rays?
Post by: RD on 12/02/2019 20:36:40
Camera flash output includes some UV ...
https://petapixel.com/2015/08/31/diy-an-ultraviolet-flash-for-black-light-photography/

Security-marker pens with built-in UV lights are cheap ...
https://www.amazon.co.uk/iZoeL-Invisible-Detective-Birthday-Children/dp/B07C12W25W/
Title: Re: What are substances or reactions that generate UV rays?
Post by: alancalverd on 12/02/2019 22:20:47
You can get battery-powered UV lamps. "Ultraviolet counterfeit detector" is available from Amazon for about 10, and there are small mains powered UV inspection lamps in engineers' tool catalogs.