[hamdani yusuf (OP)]

https://en.wikipedia.org/wiki/Balmer_series

The "visible" hydrogen emission spectrum lines in the Balmer series. H-alpha is the red line at the right. Four lines (counting from the right) are formally in the visible range. Lines five and six can be seen with the naked eye, but are considered to be ultraviolet as they have wavelengths less than 400 nm.

How can we see ultraviolet light in Balmer series?

[Bored chemist]

The definition of "ultraviolet" is a bit flexible.

[chiralSPO]

In the image provided, notice that the leftmost lines appear less intense than those on the right but still appear (to the eye, and on the screen) to be the same hue. The emissions are not actually less intense (if anything, they should be more intense, depending on how the atoms are being excited...) It's just that our eyes (and/or whatever camera was used to capture the image shown) are significantly less sensitive there.


human_cone_action_spectra.gif (7.91 kB . 766x369 - viewed 7663 times)
https://www.unm.edu/~toolson/human_cone_response.htm

[Bored chemist]

Don't forget that wat you see on a screen is determined by the camera and monitor.
In real life the 656 nm Balmer line is cherry red, but the wiki page makes it look like this.


h alpha.png (14.06 kB . 747x826 - viewed 4597 times)

[evan_au]

The lens of your eye strongly absorbs UV light, but a small amount will still get through, if the source is intense.

There are stories of people who had cataract surgery, replacing the organic lens in their eye by a glass lens.
- Apparently, the glass was much more transparent to UV than the natural lens.
- And the UV photons have more than enough energy to activate the blue cones in your retina, so these people were suddenly able to see in Ultraviolet (to a much greater degree than before the cataract surgery).
- I imagine that the focus would not have been wonderful, since the focus would have been optimized for visible light
- Some of the newer replacement lens designs include UV protection for the retina
See: https://en.wikipedia.org/wiki/Cataract_surgery

[Bored chemist]

I imagine that the focus would not have been wonderful, since the focus would have been optimized for visible light

I imagine the autofocus would probably work pretty well- just as it does with "visible" light.
The problem would be with  broadband light that couldn't all be focussed at once.

[evan_au]

imagine the autofocus would probably work pretty well

The problem with glass lenses is that they don't deform when the eye muscles tug on them - so autofocus doesn't work very well at all.
Patients with cataract surgery get to choose whether they want a reading prescription or a distance prescription for their new intra-ocular lens. Apparently, some people elect for one of each, while others elect for (say) default distance vision and a set of reading glasses...

[alancalverd]

Having been very shortsighted and worn specs every day for about 70 years, I chose short-focus replacement lenses, thus saving £400 on new varifocals and being able to read in bed without glasses - no nasty bruises if you fall asleep with your goggles on! Not sure about extended violet sensitivity, but with the cataracts gone, I'm amazed how much more air traffic there is nowadays.

[hamdani yusuf (OP)]

Don't forget that wat you see on a screen is determined by the camera and monitor.
In real life the 656 nm Balmer line is cherry red, but the wiki page makes it look like this.


h alpha.png (14.06 kB . 747x826 - viewed 4597 times)

What would happen if hydrogen in a glass container receive 656 nm laser? Where will the energy go?
Will it be converted to heat? Will the atoms emit light in different frequencies?

[Bored chemist]

What would happen if hydrogen in a glass container receive 656 nm laser?

Nothing. Hydrogen is colourless and does not absorb visible light.

Where will the energy go?

Straight through.

[hamdani yusuf (OP)]

Google search gives me this result.

The energy that an electron needs in order to jump up to a certain level corresponds to the wavelength of light that it absorbs. Said in another way, electrons absorb only the photons that give them exactly the right energy they need to jump levels. (Remember when we said that photons only carry very specific amounts of energy, and that their energy corresponds to their wavelength?)

The absorption spectrum of hydrogen shows the results of this interaction. In the visible part of the spectrum, hydrogen absorbs light with wavelengths of 410 nm (violet), 434 nm (blue), 486 nm (blue-green), and 656 nm (red). Each of the absorption lines corresponds to a specific electron jump. The shortest wavelength/highest energy light (violet 410 nm) causes the electron to jump up four levels, while the longest wavelength/lowest energy light (red 656 nm) causes a jump of only one level.



https://webbtelescope.org/resource-gallery/articles/pagecontent/filter-articles/spectroscopy-101--how-absorption-and-emission-spectra-work?

Unfortunately the article doesn't tell where the absorbed energy goes.

[Colin2B]

Unfortunately the article doesn't tell where the absorbed energy goes.

The best you can say is that it goes into changing the electron orbital in the atom, or in the case of photoelectric effect ejecting the electron from the atom.

[Bored chemist]

It's important to remember that hydrogen gas in a tube is composed of molecules, rather than atoms.
It's also important to recognise that the emission of red light from a hydrogen atom involves an electron moving from an excited state (3) to the first excited state (2) , not the ground state (1).
That process is reversible, a hydrogen atom in that excited state (2) could absorb a red photon and be promoted back to the 3rd excited state.
But very few atoms will be in that excited state (2).
Most will be in the ground state (1).

Simplistically, the energy goes into moving the electron further away from the nucleus.

[hamdani yusuf (OP)]

It's important to remember that hydrogen gas in a tube is composed of molecules, rather than atoms.

Does it apply for both emission and absorption spectra?

If the laser has a very narrow bandwidth, eventually all electrons in level 2 will go up to level 3. This will make the gas unable to absorb the laser anymore. Is there an experiment demonstrating this hypothesis?

[hamdani yusuf (OP)]

Unfortunately the article doesn't tell where the absorbed energy goes.

The best you can say is that it goes into changing the electron orbital in the atom, or in the case of photoelectric effect ejecting the electron from the atom.

Is there an experiment demonstrating photoelectric effect  in gas?
I learned that the gas could turn into plasma when exposed to microwave, or high AC voltage from Tesla coil. But they are relatively low frequency radiation compared to what causes photoelectric effect on metals.

[Bored chemist]

Yes
https://en.wikipedia.org/wiki/Photoemission_spectroscopy

[hamdani yusuf (OP)]

What would happen if hydrogen in a glass container receive 656 nm laser?

Let's make it simpler. Will the gas emit radiation in other frequency?
This question is easily answered through a real experiment. If our model is accurate enough, we should be able to deduce the result. 

[Bored chemist]

Will the gas emit radiation in other frequency?

Not much unless it is very hot.
Emission and absorption of light are essentially reversible processes.
Since hydrogen is colourless we can tell that it does not absorb light.
And, from that we can deduce that it won't emit any.
Also, because hydrogen molecules have no dipole they can't emit EM radiation as a result of changes to rotational or vibrational states.

The lowest excited states of the hydrogen molecule are somewhere in the UV. (I think they are in the far UV near 100 nm)

[hamdani yusuf (OP)]

Since hydrogen is colourless we can tell that it does not absorb light.

What we can tell from absorption spectra is that hydrogen gas doesn't interact with most frequency of visible light. But there are some frequencies that interact strongly with hydrogen. The light from the source in those frequencies become weaker after passing through hydrogen gas as received by the sensor. The gas could simply scatters it to other directions, or absorbs it and turn the energy into another form. This could be determined by experiments.

[Bored chemist]

But there are some frequencies that interact strongly with hydrogen.

No visible light interacts with hydrogen except via scattering.

This could be determined by experiments.

It was.
I looked at a test tube full of hydrogen.
It can also be determined on a theoretical basis.