2013-10-31

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Multispectral imaging-from astronomy to microscopy--from radiowaves to gammarays-FUNDAMENTALS OF SPECTROSCOPY

Sune Svanberg, Multi-Spectral Imaging (2013)

2013-10-31

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► http://www.olympusmicro.com/primer/lightandcolor/lightsourcesintro.html

Eye sensitivity

http://www.light-measurement.com/perception-of-color/, http://www.rodsbot.com/images maps cache/4533-map-assoc.jpg

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Colour Vision

http://phet.colorado.edu/en/simulation/color-vision

Papers – what causes the colour impression?

► http://www.worldwinpapers.com

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Colour schemes

Visualappearance

200 300 400 500 600 700 800 900 10000

1

2

3

4

5

6

7x 10

7

Wavelength (nm)

Em

issi

on (

W/m

2 m)

200 300 400 500 600 700 800 900 10000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Wavelength (nm)

Abs

orba

nce

(-)

200 300 400 500 600 700 800 900 10000

1

2

3

4

5

6

7x 10

7

Wavelength (nm)

Em

issi

on/R

efle

ctan

ce (

arb.

uni

ts)

200 300 400 500 600 700 800 900 10000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Wavelength (nm)

Abs

orba

nce/

Ref

lect

ance

(-)

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Absorption spectroscopy

Int.

Int.

Int.

Absorbingsample

S M

Color wheel

http://filmmakeriq.com/lessons/introduction-to-color-in-digital-filmmaking/

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Colour vision test

► http://www.egopont.com/colorvision.php

Basic Spectroscopic Arrangement

Source Sample Analyzer Detector

Calibrate for • Background (measure dark spectum and subtract it)• Intensity (often 2 arm system in a spectrophotometer)

Empty

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Absorbance measurements

Example from Nina

► Nina Reistad

Reflection spectroscopy of arm

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► Nina Reistad

Maple & Pine reflectance

► http://earthobservatory.nasa.gov/Experiments/ICE/powerpoint/Leaf_reflectance_REL.ppt

maple

pine

Similar in visible light, different in the near-IR

Ref

lect

ance

(%

)

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Energy Levels

► Sune Svanberg, Multispectral Imaging

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Energy conversions

Unit nm Joule eV Hz cm-1

1 nm 1 1.99·10-16 1.24·103 3.00·1017 1.00·109

1 Joule 1.99·10-16 1 6.24·1018 1.51·1033 5.03·1022

1 eV 1.24·103 1.60·10-19 1 2.42·1014 8.07·103

1 Hz 3.00·1017 6.63·10-34 4.14·10-15 1 3.34·10-11

1 cm-1 1.00·109 1.99·10-23 1.24·10-4 3.00·1010 1

∆/11

Wavelength Energy Frequency Wavenumber

Δ Δ

Δ Δ

600

Δ 0.001 Δ 1

Energy levels in an atom

► http://hyperphysics.phy-astr.gsu.edu/hbase/bohr.html#c4

Niels Bohr1913

λ

Energy

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The origin on quantized states in view of constructive interference

4

2∆ Schrödinger Equation

ErwinSchrödinger

1925

Hydrogen atom

410 434 486 656

∙ ∙ 13.6 ∙

Johannes Rydberg

1888

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Wave functions in the hydrogen atom

http://sevencolors.org/post/hydrogen-atom-orbitals

Wavefunction in QM: probability distribution of the electron, i.e. the electron cannot be seen as a localized particle

Quantum numbers: n - pricipal quantum numbern = 1, 2, ...l - angular quantum numberl = 0,1,2,...,n-1; s, p, d, fml - magnetic quantum number ml = -l, ..., lms - spin projection quantum number ms = -s, ..., s

Litium atom

13.6 ∙

,

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Spectrum of neutral sodium

Fine structure

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CALCIUM

Intercombinationline

Helium, Z = 2

Singlets Triplets

Spin-orbit interaction

, … . ,

Δ ∝1 1 1

2

,

,

, , ,, , ,

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BremsstrahlungCharacteristic lines

Mo 35 keV electrons

Inte

nsity

(ar

b. u

nits

)

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X-ray absorption structure

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Colors at sun set

Christine Churchill, http://epod.usra.edu/blog/2004/09/california-dreamin.html