Transcript Bez tytułu slajdu

On
the
Track
of
Modern
Physics
The human eye is rather blind, compared to the ear: it senses only one
octave of frequencies (380-760 nm) compared to 8 octaves of the ear
(50-20000 Hz). But it is well adapted to our Star emission spectrum.
The easiest spectroscopy is the optical
one. If you see you believe!
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NIR
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Solar energy intensity (W m )
UV
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First systematic investigations of spectra were done by
Bunsen and Kirchhoff between 1855 and 1863.
By optical observations, new elements, like rubidium,
purple -shining in flame, or neon, were discovered.
http://physics.kenyon.edu/EarlyApparatus/Optics/Spectrometers/Spectrometers.html
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wavelength (micrometer)
Spectrum of the Solar Radiation:
UV- ultraviolet, VIS- visible radiation, NIR – near infrared
Adapted from: http://eetd.lbl.gov/coolroof/intro.htm, Lawrence Berkeley NL, USA
To see a spectrum, anything
is good: “chromatographic”
glasses, professional spectrometer or even a CD-grating.
That of hydrogen, is the simplest with only 4 lines in the visible range.
But they were so important for quantum mechanics…
The spectrum of the 10-electron atom, neon, is already quite complicated.
Neon flashes in red, but its spectrum contains green and blue, as well.
The human eye posses two types of
receptors: rods for black and white
vision and cones for colours, with
three types of spectral sensitivity.
Optical spectroscopy can be divided into: emission, absorption, and fluorescence. What is the “real colour” , is not a trivial question.
546.1 HgI
404.6 HgI
486.4 HgI
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intensity (a.u.)
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fluorescence /arb. units
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absorbance /arb. units
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The human eye is adapted to the Solar
spectrum: rods are most sensitive in
its maximum
11-Cis Retinal is a molecule bent at 90º.
When illuminated, it stretches along,
forming a chain. Another pigment, rhodopsin serves for the black/white vision.
This graphic was produced by Rajeev Narayan
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wavelength (nm)
Glass prism
Red
Orange
Yellow
Green
Blue
Violet
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wavelength /nm
Emission spectrum of the “energy-saving” fluorescent lamp
White light
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Absorption and fluorescence spectrum of an ice-cream spoon
The Joy of Visual Perception: A Web Book
Peter K. Kaiser, York University
http://www.yorku.ca/eye/
What we see, we believe.
But even if we do not see,
we must believe.
Our vision is different than that of
honey-bees [1].
They react best to monochromatic
patters, in particular to the yellow but
posses also receptors of ultraviolet
(with maximum efficiency at 344 nm).
What is above the visible
light, we call under-red,
what is below: above-violet.
Bees see by the contrast with the
green and ignore the brown colour.
You can not see the infrared
but your digital camera can.
You do not feel ultraviolet,
but these plastics (and Your
skin) does.
[1] Silke Stach, Julie Benard and Martin Giurfa,
Local-feature assembling in visual pattern recognition and
generalization in honeybees, Nature 429, 758-761 ( 2004)
Goethe and Newton wrote treaties about colours.
Colours are different for snakes and bees.
For You, they are Your own. Just paint!
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