Post by: hamdani yusuf on 28/12/2021 11:24:30
(https://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Visible_spectrum_of_hydrogen.jpg/900px-Visible_spectrum_of_hydrogen.jpg)
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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?
Post by: Bored chemist on 28/12/2021 12:11:49
Post by: chiralSPO on 28/12/2021 16:19:30
human_cone_action_spectra.gif (7.91 kB . 766x369 - viewed 7361 times)https://www.unm.edu/~toolson/human_cone_response.htm
Post by: Bored chemist on 28/12/2021 17:30:43
In real life the 656 nm Balmer line is cherry red, but the wiki page makes it look like this.
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Post by: evan_au on 28/12/2021 20:57:44
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
Post by: Bored chemist on 28/12/2021 22:36:02
I imagine that the focus would not have been wonderful, since the focus would have been optimized for visible lightI 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.
Post by: evan_au on 29/12/2021 07:52:08
Quote from: bored chemist
imagine the autofocus would probably work pretty wellThe 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...
Post by: alancalverd on 29/12/2021 23:32:37
Post by: hamdani yusuf on 30/12/2021 09:53:56
Don't forget that wat you see on a screen is determined by the camera and monitor.What would happen if hydrogen in a glass container receive 656 nm laser? Where will the energy go?
In real life the 656 nm Balmer line is cherry red, but the wiki page makes it look like this.
Will it be converted to heat? Will the atoms emit light in different frequencies?
Post by: Bored chemist on 30/12/2021 10:11:30
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.
Post by: hamdani yusuf on 31/12/2021 05:02:43
Quote
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?)Unfortunately the article doesn't tell where the absorbed energy goes.
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/files/live/sites/webb/files/home/webb-science/in-depth-articles/_images/Spectroscopy/Article4/AbsorptionByHydrogen.png)
https://webbtelescope.org/resource-gallery/articles/pagecontent/filter-articles/spectroscopy-101--how-absorption-and-emission-spectra-work?
Post by: Colin2B on 31/12/2021 08:35:18
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.
Post by: Bored chemist on 31/12/2021 10:30:27
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.
Post by: hamdani yusuf on 31/12/2021 11:39:46
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?
Post by: hamdani yusuf on 31/12/2021 11:46:16
Is there an experiment demonstrating photoelectric effect in gas?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.
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.
Post by: Bored chemist on 31/12/2021 12:07:26
https://en.wikipedia.org/wiki/Photoemission_spectroscopy
Post by: hamdani yusuf on 31/12/2021 14:53:26
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.
Post by: Bored chemist on 31/12/2021 15:18:16
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)
Post by: hamdani yusuf on 01/01/2022 04:07:42
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.
Post by: Bored chemist on 01/01/2022 11:18:32
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.
Post by: hamdani yusuf on 02/01/2022 02:43:57
It was.Can you tell us more about your experience? Do you have any pictures?
I looked at a test tube full of hydrogen.
What's the characteristic of the scattered light? Is it bright enough to be seen with naked eyes?
How is the distribution of the scattered light? Does it produce reflected light?
If the laser is polarized vertically, does the gas scatter the light upward?
I'm sorry if I ask too much. Your help will be greatly appreciated.
Post by: Bored chemist on 02/01/2022 10:17:00
Can you tell us more about your experience?It looked like a test tube full of air.
Post by: hamdani yusuf on 02/01/2022 13:27:16
It looks like I have to do the experiment myself.Can you tell us more about your experience?It looked like a test tube full of air.
Post by: Bored chemist on 02/01/2022 16:42:22
What do you expect to see?It looks like I have to do the experiment myself.Can you tell us more about your experience?It looked like a test tube full of air.
Hydrogen looks like air.
Post by: hamdani yusuf on 02/01/2022 17:04:32
What do you expect to see?I expect to see scattered light if the frequency is in Balmer series, and no scattered light when it's not.
Hydrogen looks like air.
If the scattered light is too dim we can just increase the intensity of the laser beam.
Post by: hamdani yusuf on 02/01/2022 17:07:17
No visible light interacts with hydrogen except via scattering.If this is true, then the absorption spectrum of hydrogen is a misnomer. We should call it scattering spectrum instead.
Post by: Bored chemist on 02/01/2022 17:18:18
Not really.No visible light interacts with hydrogen except via scattering.If this is true, then the absorption spectrum of hydrogen is a misnomer. We should call it scattering spectrum instead.
The absorption spectrum of hydrogen gas near room temperature all the way from the microwave up to the vacuum ultraviolet is a flat line at zero.
Hydrogen gas does not absorb any of that EM radiation.
If you have a spectrum that shows any absorptions then it is wrong, or mislabeled somehow.
Post by: Bored chemist on 02/01/2022 17:23:43
Yes, and I have done that sort of experiment when i was a student (with an NMR transition, rather than a visible one, but the principle is the same),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?
More generally
https://en.wikipedia.org/wiki/Spectral_hole_burning
and
https://en.wikipedia.org/wiki/Saturable_absorption
Post by: chiralSPO on 02/01/2022 17:59:12
Post by: hamdani yusuf on 02/01/2022 21:49:08
Post by: Bored chemist on 02/01/2022 22:53:31
I guess it's significantly lower than melting point of glass.Very roughly 10,000 degrees.
Hot enough to boil glass (and anything else).
Post by: Bored chemist on 02/01/2022 23:04:37
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.You can run an arc with DC.
The frequency is not relevant.
Post by: hamdani yusuf on 03/01/2022 00:16:40
So, the absorption spectrum can't be observed in a desktop laboratory equipments? How did they produce those data?I guess it's significantly lower than melting point of glass.Very roughly 10,000 degrees.
Hot enough to boil glass (and anything else).
Post by: hamdani yusuf on 03/01/2022 00:17:33
Post by: chiralSPO on 03/01/2022 01:55:09
As an undergraduate student in a general chemistry laboratory class, I used such devices (for many different elements) as well as a diffraction grating to observe their emission spectra.
I have observed the absorption spectrum of H by analysis of the light from the sun (dark line spectrum, or "Fraunhofer lines")
Post by: hamdani yusuf on 03/01/2022 04:51:03
Emission spectra can be produced in a bench-top (or hand-held) vapor discharge lamp. Low pressure H2 can be broken down by a high voltage: https://www.flinnsci.com/hydrogen-gas-spectrum-tube/ap1334/I've seen a diagram in a physics article showing that hot hydrogen gas produces emission spectra while cool hydrogen produces absorption spectra. How far from the truth can it be?
As an undergraduate student in a general chemistry laboratory class, I used such devices (for many different elements) as well as a diffraction grating to observe their emission spectra.
I have observed the absorption spectrum of H by analysis of the light from the sun (dark line spectrum, or "Fraunhofer lines")
Post by: chiralSPO on 03/01/2022 05:24:34
I've seen a diagram in a physics article showing that hot hydrogen gas produces emission spectra while cool hydrogen produces absorption spectra. How far from the truth can it be?
Cold hydrogen will not emit, only hot. Both hot and cold will absorb.
Post by: evan_au on 03/01/2022 07:26:49
Quote from: hamdani yusuf
does the hot gas emit observable thermal radiation? Is there any resemblance to the black body radiation?Yes, the Sun is composed of hot gas (primarily line spectrum), and even hotter plasma (primarily black body radiation).
- In a hot gas, the electrons are in defined shells around the nucleus, with defined energy levels. This produces a line spectrum (absorption and emission lines with specific photon energies)
- In a plasma, electrons are not bound to any particular nucleus, but can take any energy approaching or leaving the vicinity of a nucleus (or another electron). This produces a continuous spectrum (black body radiation, with photons of all energy levels).
See: https://en.wikipedia.org/wiki/Sunlight#Composition_and_power
Post by: hamdani yusuf on 03/01/2022 08:15:32
So, this diagram is misleading then?I've seen a diagram in a physics article showing that hot hydrogen gas produces emission spectra while cool hydrogen produces absorption spectra. How far from the truth can it be?
Cold hydrogen will not emit, only hot. Both hot and cold will absorb.
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https://casswww.ucsd.edu/archive/public/tutorial/Stars.htmlI found many like this on line, such as.
University of California, San Diego
Center for Astrophysics & Space Sciences
We may consider three principal types of spectra which appear when the light from an object is broken up into its component wavelengths or "dispersed":
a continuous spectrum or continuum; the emission of a thermal spectrum is one type of continuum.
an absorption spectrum or sometimes an absorption-line spectrum.
an emission spectrum or emission-line spectrum.
(https://casswww.ucsd.edu/archive/public/tutorial/images/physics/em_abs.gif)
(https://claesjohnsonmathscience.files.wordpress.com/2012/03/types_of_spectra.jpg)
and
(https://image.shutterstock.com/image-vector/absorption-spectrum-hydrogen-atom-600w-1305568666.jpg)
Post by: hamdani yusuf on 03/01/2022 08:24:28
Hydrogen discharge tubes are available on line. They produce Balmer spectrum without causing the glass to boil.I guess it's significantly lower than melting point of glass.Very roughly 10,000 degrees.
Hot enough to boil glass (and anything else).
Post by: Bored chemist on 03/01/2022 10:02:47
The glass is much much colder than the gas.Hydrogen discharge tubes are available on line. They produce Balmer spectrum without causing the glass to boil.I guess it's significantly lower than melting point of glass.Very roughly 10,000 degrees.
Hot enough to boil glass (and anything else).
So, this diagram is misleading then?It depends on the gas and other details.
Chlorine is a yellow colour; you would see absorption lines in the blue and violet regions of the spectrum.
Trifluoronitrosomethane is blue- you would see absorption lines from about 500 to 700 nm.
And hydrogen is colourless, so you see no absorption at all.
Whether or not you see an absorption or emission spectrum in the case marked "absorption spectrum of hydrogen atom" depends on how bright the white light source is.
But you would also see the spectra of other things like H2, H2+ H3+ etc
Post by: hamdani yusuf on 03/01/2022 12:47:54
The glass is much much colder than the gas.How did you determine the temperature of the gas?
Post by: evan_au on 04/01/2022 02:23:07
- Helium (named after the ancient Greek Sun god Helios): An element which makes up about 25% of the Sun, but which had not been previously discovered and purified on Earth
- Other "new" elements which turned out to be known elements, but at extreme temperatures and low pressures that had never been produced on Earth (eg highly ionised iron atoms in the Sun's corona, at a temperature of millions of degrees)
Post by: hamdani yusuf on 04/01/2022 04:17:05
The definition of "ultraviolet" is a bit flexible.OK. We can read it in another Wikipedia article that the limits of visible spectrum may be different among individuals and conditions.
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https://en.wikipedia.org/wiki/Visible_spectrumI think the most probable reason to set the limit at 400 nm as quoted in the first post is due to rounding value.
A typical human eye will respond to wavelengths from about 380 to about 750 nanometers.[1] In terms of frequency, this corresponds to a band in the vicinity of 400–790 terahertz. These boundaries are not sharply defined and may vary per individual.[2] Under optimal conditions these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared).[3][4] The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well.[5]
Post by: Bored chemist on 04/01/2022 08:31:11
How did you determine the temperature of the gas?Doppler broadening and also the spectrum. The hotter the material, the more shorter wavelength radiation it produces
Post by: hamdani yusuf on 04/01/2022 12:18:59
How does the glass of the discharge lamp withstand the high temperature? Why doesn't it evaporate when touching the glowing hydrogen plasma?How did you determine the temperature of the gas?Doppler broadening and also the spectrum. The hotter the material, the more shorter wavelength radiation it produces
Post by: Bored chemist on 04/01/2022 15:52:24
Because it is being cooled by the air outside, but only heated by a near vacuum inside.How does the glass of the discharge lamp withstand the high temperature? Why doesn't it evaporate when touching the glowing hydrogen plasma?How did you determine the temperature of the gas?Doppler broadening and also the spectrum. The hotter the material, the more shorter wavelength radiation it produces
Also, have a good look at a discharge tube. The light is emitted from the plasma at the centre of the tube, not the cool bit near the glass.
Gases are poor conductors of heat.
Post by: wadhvakartik22 on 18/01/2022 11:33:33
Post by: alancalverd on 18/01/2022 13:52:57
Post by: hamdani yusuf on 18/01/2022 21:33:44
Frequency isn't the criterion: energy transfer is what matters. Most common gases require about 15 - 30 eV to ionise because the electrons are tightly bound to the molecules, but electrons in a solid metal are considerably freer and can be ejected by visible or ultraviolet photons from 2 eV upwards. The initiating mechanisms of "field" (static or alternating voltage) versus "impact" (photon) ionisation are different and often confused because we use static-field ion cascade multiplication (geiger or proportional counters) to detect single photon events.What determines the energy transfered?
Post by: yor_on on 20/01/2022 14:33:32
" ! Not sure about extended violet sensitivity, but with the cataracts gone, I'm amazed how much more air traffic there is nowadays. "
Post by: Iannguyen on 09/02/2022 13:51:15
Four wavelengths in the visible spectrum of hydrogen light, 410 nm, 434 nm, 486 nm, and 656 nm, corresponding to photon emissions by excited electrons transitioning to the quantum level defined by the primary quantum number n = 2. With wavelengths less than 400 nm, there are numerous noteworthy UV Balmer lines. As the UV spectrum approaches a limit of 364.5 nm, the number of these lines becomes an endless continuum. The model also clarifies the Balmer formula for hydrogen spectral lines. In the Bohr formula, light energy is the difference in energies between the two orbits. The Balmer series in a hydrogen atom connects the wavelength of the emission seen by scientists to the probable electron transitions down to the n = 2 positions. When electrons travel between different energy levels surrounding the atom (defined by the primary quantum number, n ), they either emit or absorb a photon, according to quantum physics. The Balmer series defines the wavelengths of emitted photons as well as transitions from higher energy levels to the second energy level. The Rydberg formula can be used to compute this.
The Balmer series' "visible" hydrogen emission spectrum lines. The red line on the right is H-alpha. The viewable range consists of four lines (counting from the right). Lines 5 and 6 are visible to the human eye, although they are classified as ultraviolet since their wavelengths are shorter than 400 nm.
Post by: Bored chemist on 09/02/2022 18:52:04
In atomic physics, the Balmer series (or Balmer lines) is one of six named series that describe the spectral line emissions of the hydrogen atom. The Balmer series is determined using the Balmer formula, which was established by Johann Balmer in 1885 and is an empirical equation.Why have you paraphrased the wiki page?
Four wavelengths in the visible spectrum of hydrogen light, 410 nm, 434 nm, 486 nm, and 656 nm, corresponding to photon emissions by excited electrons transitioning to the quantum level defined by the primary quantum number n = 2. With wavelengths less than 400 nm, there are numerous noteworthy UV Balmer lines. As the UV spectrum approaches a limit of 364.5 nm, the number of these lines becomes an endless continuum. The model also clarifies the Balmer formula for hydrogen spectral lines. In the Bohr formula, light energy is the difference in energies between the two orbits. The Balmer series in a hydrogen atom connects the wavelength of the emission seen by scientists to the probable electron transitions down to the n = 2 positions. When electrons travel between different energy levels surrounding the atom (defined by the primary quantum number, n ), they either emit or absorb a photon, according to quantum physics. The Balmer series defines the wavelengths of emitted photons as well as transitions from higher energy levels to the second energy level. The Rydberg formula can be used to compute this.
The Balmer series' "visible" hydrogen emission spectrum lines. The red line on the right is H-alpha. The viewable range consists of four lines (counting from the right). Lines 5 and 6 are visible to the human eye, although they are classified as ultraviolet since their wavelengths are shorter than 400 nm.
Post by: hamdani yusuf on 10/02/2022 02:39:20
Post by: Bored chemist on 10/02/2022 08:40:20
Does anyone know how to derive Balmer series from Schrodinger's wave equation?The internet knows.
https://chem.libretexts.org/Courses/University_of_California_Davis/UCD_Chem_107B%3A_Physical_Chemistry_for_Life_Scientists/Chapters/4%3A_Quantum_Theory/4.10%3A_The_Schr%C3%B6dinger_Wave_Equation_for_the_Hydrogen_Atom
Post by: hamdani yusuf on 15/02/2022 10:29:51
Quote
https://chem.libretexts.org/Courses/University_of_California_Davis/UCD_Chem_107B%3A_Physical_Chemistry_for_Life_Scientists/Chapters/4%3A_Quantum_Theory/4.10%3A_The_Schr%C3%B6dinger_Wave_Equation_for_the_Hydrogen_Atom
It is interesting to compare the results obtained by solving the Schrödinger equation with Bohr’s model of the hydrogen atom. There are several ways in which the Schrödinger model and Bohr model differ.
- First, and perhaps most strikingly, the Schrödinger model does not produce well-defined orbits for the electron. The wavefunctions only give us the probability for the electron to be at various directions and distances from the proton.
- Second, the quantization of angular momentum is different from that proposed by Bohr. Bohr proposed that the angular momentum is quantized in integer units of ℏ , while the Schrödinger model leads to an angular momentum of
.
- Third, the quantum numbers appear naturally during solution of the Schrödinger equation while Bohr had to postulate the existence of quantized energy states. Although more complex, the Schrödinger model leads to a better correspondence between theory and experiment over a range of applications that was not possible for the Bohr model.
I wonder how different values of angular momenta in different models can lead to the same result in hydrogen spectrum.
Post by: hamdani yusuf on 15/02/2022 10:35:53