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This phosphorescence effect is used in Oscilloscope screens where we want persistence of the image.

In mercury lamps the fluorescence effect is used. In a mercury tube, a vacuum tube contains a drop or two of molten mercury along with inert Argon gas. This is vaporized and a large voltage is applied to cause an electric discharge in mercury vapour. In the process the mercury atoms are ionized. Almost instantaneously ionized atoms neutralize by the process of spontaneous emission and emit Ultra Violet light which is invisible. The UV light strikes the walls of the tube which is coated with fluorescence material called phosphor. This coating gets excited by the absorption of UV light and immediately relaxes to the ground state by emitting soft white light. Here relaxation time is of the order of nanosecond. Hence Mercury Tube is also called Fluorescence Tube. Flourescence is much more efficient than Incandescence used in Incandescent Lamps invented by Thomas Alva Edison [Appendix XXXII ] .

In a similar fashion the discharge in various gases cause spontaneous emission of various colored light.

Mercury Discharge Physics :

Hg(vapor) + collision energy(4.9eV) = Hg* (ionized mercury atoms);

(Collision Energy is caused by highly accelerated ionized particles in presence of critical electric field. The ionized particles are caused due to cosmic particles striking the mercury vapor atoms).

Hg* = Hg + 4.91eV

And λ= 1.24/(4.91eV)= 0.252μm ( Ultra-violet light );

1 st ionization energy ( energy required for stripping the outermost electrons) = 2.00eV.

Sodium Vapor Discharge Lamp :

Na + collision energy (2.85eV)= Na*

Na* = Na + 2.85eV photon;

And λ= 1.24/(2.85eV)= 0.435μm ( Yellow light );

First Ionization Energy : E 1 = 495 KJ/MOLE; (0.93eV)

Second Ionization Energy : E 2 = 4560 KJ/MOLE;

Third Ionization Energy : E 3 = 6900 KJ/MOLE;

Fourth Ionization Energy : E 4 = 9540 KJ/MOLE;

Fifth Ionization Energy : E 5 = 13400 KJ/MOLE;

Sixth Ionization Energy : E 6 = 16600 KJ/MOLE;

In first ionization the outermost electrons are being ripped apart from the atom. In second ionization, the second outermost electrons are being ripped apart from the atom. And so on.

Neon Discharge Lamp :

Ne + collision energy(10.6eV) = Ne* Ne* = Ne + Orange-red light ;

E 1 = 2080, E 2 =3950, E 3 =6120, E 4 =9370, E 5 = 12200, E 6 = 15000 (KJ/MOLE);

First ionization energy = 4.84eV

Argon Discharge Lamp :

Ar + collision energy(7.7eV) = Ar*

Ar* = Ar + Bluish Purple ;

E 1 = 1521, E 2 =2666, E 3 =3900, E 4 =5770, E 5 = 7240, E 6 = 8800 (KJ/MOLE);

First ionization energy = 3.2eV

Krypton Discharge Lamp:

Kr + 6.8eV(1400 KJ/Mole) = Kr*

Kr* =Kr + White light

First ionization energy = 2.94eV

Helium Discharge Lamp :

He +12.3eV(2373 KJ/MOLE) =He *

He* =He + ?

E 2 =5248 KJ/MOLE

Hydrogen Discharge Lamp:

H + 7.18eV = H*

Stimulated Emission Phenomena:

Stimulated Emission is induced emission when incident photon matches the transition energy . This effect is used in LASER( Light Amplification by Stimulated Emission Radiation).

In Fig.(1.19) the spontaneous emission is shown.

In Fig.(1.20) the stimulated mission is shown.

Fig.(1.19). The mechanism of Spontaneous Emission.

Fig(1.20). The mechanism of Stimulated Emission.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Solid state physics and devices-the harbinger of third wave of civilization. OpenStax CNX. Sep 15, 2014 Download for free at http://legacy.cnx.org/content/col11170/1.89
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