this is useful for all science student

1. Presented by

2. Quantum
Classical
Energy continuous
Energy discrete
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3. 3
Electron in preticuler
elergy leval called orbital

4. Collision
of light
and
electron
High
Energy
Removal
of electron
Medium
energy
Electron
Transfer
high
energy
leval
Low
enegry
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5. S0 ground state
S1 or S2 is excited singlet state
T1 is triplet excitation state
S0 S1 S2 T1 also have vibration energy leval
Radiative transitions
Absorption
Fluorescence
phosphorescence
Non-radiative transitions
 Intersystem Crossing
 Vibrational Relaxation
 Internal Conversion
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6. Fluorescence
Fluorescence is the emission of light by a substance
Mechanism:
Excitation: S0 + hvex Sm
Fluorescence (emission): Sn Sm+ hvem
Vem is visible reason frequency
h is Planck’s constant
Quantum yield
Ø= number of photon emitted
number of photon adsorbed
kinetics
Fluorescence typically follows first-order kinetics
[S1]=[S1]0e-Ѓt
Ѓ is the decay rate or the inverse of the fluorescence lifetime.
[s1] is the concentration of excited state molecules at time
[s1]0 is the initial concentration
The maximum possible
fluorescence quantum yield is 1.0
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Fluorescence intensity, IF is proportional to the amount of light absorbed and the
fluorescence quantum yield, Φ
If=kIoϕ[1-(10-εbc)]
where
k is a proportionality constant attributed to the instrument
I0 is the incident light intensity ϵ is the molar absorptivity,
b is the path length, c is the concentration of the substrate.
Stokes shift
Stokes fluorescence is the emission of a longer-wavelength photon (lower
frequency or energy) by a molecule
Anti-Stokes shift
If the emitted photon has more energy than the absorbed photon, the energy
difference is called an anti-Stokes shift.
this extra energy comes from dissipation of thermal phonons in a crystal lattice,
cooling the crystal in the process.
Fluorescence

8. laws of Fluorescence
There are several general rules that deal with fluorescence.
• Ground state spin multiplicity does not
change
• Follow spin selection rule
• Vibronic transitions are the simultaneous changes in
electronic and vibrational energy levels
• electronic transitions are very fast compared with
nuclear motions
• Stokes shift is the difference between positions of the
band maxima of the absorption and emission spectra
• This is because Non-radiative transitions
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9. Pigment cells that exhibit fluorescence are called fluorescent
Fluorescence
serves a wide
variety of
functions in
coral
Fluorescent
proteins in
corals may
contribute to
photosynthesis
Siphonophorae
is an order of
marine animals
exhibit yellow
to red
fluorescence
fish jellyfish Coral
Siphono
phorae
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10. several families
of frogs, salama
nders and caeci
lians show
Fluorescence
polka-dot tree
frog show
Fluorescence
new compound
found in
the lymph and
skin glands
butterflies have
complex systems for
emitting fluorescent
light.Their wings
contain pigment-
infused crystals that
provide directed
fluorescent light.
Parrots have
fluorescent
plumage that
may be used in
mate signaling
Many plants
are fluorescent
due to the
presence
of chlorophyll
Ex.
The Mirabilis
jalapa flower
contains violet,
and yellow,
fluorescent
betaxanthins.
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Common materials that fluoresce
Vitamin B2 fluoresces yellow.
Tonic water fluoresces blue due to the presence of quinine.
Highlighter ink is often fluorescent due to the presence of pyranine.
Banknotes, postage stamps and credit cards often have fluorescent
security features.
Organic solutions such anthracene or stilbene dissolved
in benzene or toluene show fluoresces
Scintillation is defined a flash of light produced in a transparent material
by the passage of a particle

12. Quantum dots(rising star of nano techanology)
Quantum dots are unique 0 dimention nanocrystals, 1–100 nm in
size, with unique optical and electrical properties.
Quantum dots are latest fluorescent compound
Fluorescent property of quantum dots depends their size.
Size decrease energy gap increase, so they show different colour in different size
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13. 13
• fluorescent
lamp
• LED lamps
Analytical
chemistry
• detecter
• Thin-layer
chromatography
Spectroscopy
• Fluorescence
spectroscopy
• fluorescence resonance energy transfer
• Fluorescent glucose biosensors
•Fluorescence Lifetime
•Imaging Microscopy
life
science
non-destructive
way of tracking
or analysis

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Phosphorescence is a type of photoluminescence. Phosphorescence is
emission of light from triplet-excited states.
absorbing the light and reemitting it at a
longer wavelength
Excitation: S0 + hvex Sm
Intersystem crossing: Sm  Tp
Fluorescence (emission): Tp So+ hvem
Zinc sulfide (left) and strontium aluminate (right), in visible
light, in darkness, and after 4 minutes in the dark.
S is a singlet and T a triplet
Transitions to the ground state are , and the emission
rates are relatively slow (103 to 100 s−1)

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 a phosphorescent material does not immediately reemit the radiation it
absorbs. Instead, a phosphorescent material absorbs some of the radiation
energy and reemits it for a much longer time after the radiation source is
removed
phosphorescent materials may continue to emit an after glow ranging
from a few microseconds to many hours after the excitation is removed
Phosphorescence is usually not seen in fluid solutions at
room temperature because there are many deactivation
processes that have faster rate constants

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copper-activated zinc sulfide, called ‘GS
phosphor.
This type of pigment is often used in the
manufacture of novelty toys
strontium aluminate is 10 times more luminous
than zinc sulphide. This has more serious
applications such as safety signs,
Phosphorescent pigments can be mixed with
paints, giving a ‘glow’ effect. In fact, the
pigments can be mixed with almost any medium
including candle wax, glue and plastic inks

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 phosphorescent materials are the glow-in-the-dark toys, stickers, paint,
wristwatch and clock dials that glow after being charged with a bright
light such as in any normal reading or room light.
 Phosphorimetry is application of Phosphorescence, which is used in
clinical, forensic application etc.
 study of proteins
 It use as Molecular Phosphorescence Spectroscopy
 Oxygen Measurement
 organic light-emitting diodes (OLEDs)

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