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ArcticMyst Security by Avery

Question about UVC light.

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I started researching a little more on UV light this evening and found there are 3 types of UV light. UV-A/UV-B, and the most dangerous UV-C. Alright I got that! What I would like answers to are the following questions:

-What would happen if let's say 5mW of 266nm hit your hand for 1 sec? 10 secs? What about 100mW?

-Once hit with UV-C light, is the damage permanent?

-If you were to be constantly attacked with UV-C rays how long could one last?

I appreciate the time to answer these :)

-Alex
 





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I think it would be very similar to the damage caused by ionizing radiation. I don't know how many mW of UVC is equal to what level of exposure to the different types of radiation though. 5 mw at 1 second and 10 seconds I doubt would do any noticable damage. Might damage the DNA in your cells, but your body is capable of healing DNA damaged by radiation. 100 mW might give you a small spot similar to sunburn, or give you a freckle.

The damage likely wouldn't be permanent as I mentioned above your body can heal damaged DNA.

As to how long you would last, thats an interesting one. Though it has similar DNA damaging properties to ionizing radiation, I don't think it has the penetrating power. So one possibility might be that it keeps killing off outer layers of skin, and as the old skin falls away damages the stuff underneath, essentially killing you layer by layer.
 

DrSid

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I agree. The burning power would be similar to blue light. But it will have the bonus of possibly causing cancer in the future. Now 'how much' will be pretty hard question, as there is no clear agreement on it for any kind of ionizing radiation.
 
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Alright, thank you for answering.

I always thought 266nm was a wavelength capable of going through your arm(i.e) in a few seconds due to how short it is, and destroying everything in the way. Is that true or?

-Alex
 
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Alright, thank you for answering.

I always thought 266nm was a wavelength capable of going through your arm(i.e) in a few seconds due to how short it is, and destroying everything in the way. Is that true or?

-Alex

This likely doesn't happen until you get to gamma rays. A gamma ray will tear you, bones and all, leaving a trail of damage.
 
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This likely doesn't happen until you get to gamma rays. A gamma ray will tear you, bones and all, leaving a trail of damage.

Gotcha, I appreciate it! Is a gamma laser even possible? And what would be it's wavelength? 1nm?

-Alex
 
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I know you would certainly kill any bugs or bacterria with that wavelength , I kno fluros are different in concentration etc but 254nm is used for hand washing basins in some critical hygeine applications too , it would be an awesome laser to have for exiting minerals, stones rocks etc
 
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According to Wikipedia, gamma rays have a wavelength <10 picometers, which is smaller than an atom.

From what I've read, some around LPF, xray lasers are extremely difficult and impractical. I doubt anyone will produce a gamma laser anytime soon...
 
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According to Wikipedia, gamma rays have a wavelength <10 picometers, which is smaller than an atom.

From what I've read, some around LPF, xray lasers are extremely difficult and impractical. I doubt anyone will produce a gamma laser anytime soon...

Wow alright then! So is the shortest wavelength available in a laser 266nm? I think I also heard of 254nm, but not sure that exist.

-Alex
 
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254nm is a primary emission wavelength of low pressure Mercury (Hg) excitation. It isn't a laser line (except for maybe an experimental HeHg with proprietary mirrors).

That being said, UVC IS NOT IONIZING RADIATION. (neither is 254nm). UVC can excite molecules into an elevated level, but not atoms. It is simply "short wave" UV. It penetrates deeper into skin than most commonly encountered photons, but certainly does not pass through you. The primary mode of cell damage is through oxidative stress and DNA damage that leads to replication errors and eventually to apoptosis and possibly runaway mitosis (onset of cancer). This is why 254nm is used as a sterilization lamp.

I have several 40 Watt 254nm sterilization lamps. As long as you remember the inverse squared law they're pretty harmless other than cumulative exposure increasing the risk of skin cancer. A damaging level of exposure varies from person to person but the earliest level of damage is a bad sun-burn. My wife is far more sensitive to it than I am, but I worked as a welder for many years where I was exposed to much higher levels than she will ever be. I was also exposed to much higher intensities, as well as much shorter wavelengths (<200nm). The eyes are particularly sensitive as the cornea and lens absorb all light shorter than about 300nm. Corneal burns are incredibly painful and debilitating when severe. In addition the risk for permanent damage and resultant blindness is present.

Below 200nm UV can start to do interesting things to certain molecules. Hg also has a strong emission line at 185nm. 185nm is strongly absorbed by diatomic oxygen (O2) in the atmosphere, and as such air is nearly opaque to it, leading to very short mean-free-paths for such short wave UV. Since it is intensely absorbed by O2 it breaks the O2 into monoatomic/singlet Oxygen (O) which then recombines with itself and adjacent atmospheric O2 into O3, Ozone: (3O2 -> 2O3, and O2 -> 2O + O2 -> 2O3). Ozone is a strong oxidizer and carries it's own health hazards and interesting properties. Interestingly too, 254nm is strongly absorbed by Ozone, and in doing so splits Ozone back into O2: (2O3 -> 3O2). The cyclic nature of 185nm and 254nm on Oxygen leads to an oxidative scrubbing action which can both intensely clean and disinfect surfaces. Full spectrum special grade quartz-glass low pressure Hg lamps are sources of both 185nm and 254nm and are employed for just this purpose. They are hard to get a hold of though because of the increased danger of Ozone. Most commercial germicidal UV lamps are made so that no <200nm light escapes, and rely solely upon the DNA damaging aspect of 254nm to disinfect. When I was a young boy I had a 200W full spectrum Hg lamp. When I moved away my parents junked it against my wishes. You could fill a medium room with toxic levels of Ozone in just a few minutes. I loved that lamp.
 
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According to Wikipedia, gamma rays have a wavelength <10 picometers, which is smaller than an atom.

From what I've read, some around LPF, xray lasers are extremely difficult and impractical. I doubt anyone will produce a gamma laser anytime soon...

In terms of wavelength, gamma rays and x-rays are basically the same thing, i.e. photons with energy exceeding that of shortwave UV. The difference is in their origin.

By modern convention, x-rays are high-energy photons originating from processes and interactions involving electrons. Bremsstrahlung is one example, high-energy synchrotron radiation is another (although synchtrotron radiation can also be low-energy, e.g. microwaves, depending on how the device is set up.) The free-electron laser would, by this convention, produce x-rays rather than gamma rays, assuming the device is configured to produce photons of such energy.

Gamma rays are high-energy photons originating from nuclear transitions and reactions; photons arising from such processes are always termed 'gamma radiation' regardless of energy. While in most cases such photons will be more energetic than bremsstrahlung and other x-radiation (due to nuclear transitions being inherently highly energetic) this is not necessarily the case.

As an example, when a cobalt-60 nucleus decays it emits gamma rays with energies somewhat higher than 1 MeV. The photons are termed 'gamma rays' because they arise from a nuclear reaction, in this case a radioactive decay and subsequent relaxation of the daughter nucleus into its ground state.

On the other hand, the Edwards Accelerator Laboratory here at Ohio University can accelerate electrons up to 5 MeV energy, and if these are directed at a target, bremsstrahlung x-rays of up to 5 MeV can be produced. These photons are termed "x-rays" because they arise from the deceleration / change of motion of electrons, even though they are more energetic than the cobalt-60 gamma rays mentioned above.

I'm sure I left out some detail or another, but that is basically how x-rays and gamma rays are distinguished in modern physics. In common parlance, the older, energy-based distinction still predominates.
 
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djQUAN

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IIRC, UVC can cause cataracts with prolonged exposure. Not 100% sure of that though
 
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