Ch. 21 Optical Properties Flashcards
Lightspeed
3 x 10 ^ 8
C = ??
C = Frequency * Wavelength
Energy of photon formula
E = h (plancks constant) * v
Light interaction with solids formula
I0 = It (transmitted) + Ia (absorved) + Ir (reflected)
Electron can jump to higher energy level if hit by…
photon (excited state)
Electron jump to energy level same as
energy of photon
Optical properties of metals
they can absorb a lot of light frequencies
Surface required of metals to absorb photons
0.1 micrometers
When e- stops being excited, it releases a -
photon
% of light reflected
rest is heat
Reflectivity of metals formula
= Ir / I0
The atom gets distorted when…
it emits light
Index of refraction formula
n = c / v
Total internal reflectance formula
n1 / n2 = sin θ2 / sin θ1
what is θc
angle where the reflacted light acts between both materialsR
Reflection of non-metals
R = ( (n2 - n1) / (n2 + n1) ) ^2
Absorption of light of frequency v by e- occurs if
hv > Egap
Blue light energy
hv = 3.1 ev
Red light energy
hv = 1.7 ev
Egap
Opaque - 1.7 - Colored - 3.1 - Transparent
Translucency is caused by:
caused by inside scattering
Translucency can be caused by
grain boundaries, fine pores, phases
Amorphous pore free polymers are:
transparent
Semi crystalline polymers are:
transluscent or opaque, depends on %crystallinity, boundaries causes scattering
If residence time is > 10^-8s
phosphorescenic
if residence time is < 10^-8s
fluorescence
Photoconductivity process
photon hits semiconductor - e- transitions to conduction band - profit?
LEDs (light emmiting diode) process
EXPLAIN
LASER stands for
Light amplification by the stimulated emission of radiation
Distance between laser mirrors is
2L = Nλ
Bouncing of light is fixed by:
step index
