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I"- Quelques"rappels"sur"la"lumière"et"les"couleurs"
I.1 Qu’est-ce que la lumière ?
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I.2 La perception des couleurs
a) Lumière monochromatique
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b) Lumière polychromatique
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I.3 La lumière transporte de l’énergie
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Note$=!E,22%!5:d.5!-(2#.+8!5%!)19%4/%()!0(!'4%9/),4-,/,2?/)%!#!(+%!'%+'.;.5./1!/)?'!6#).#;5%!'%5,+!5#!
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violet
bleu
vert
orange
jaune
rouge
400
440
500
560
590
610
700
à 800

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"#$%!R!'()!&&!
II"- Le"spectrophotomètre"UV-visible"
II.1 Description de l’appareil
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Schéma&simplifié&d’un&spectrophotomètre&
Remarque$:$la$plupart$des$appareils$récents$fonctionnent$sur$un$principe$différent.$L’échantillon$est$
éclairé$en$lumière$blanche,$puis$le$signal$en$sortie$est$analysé$par$un$traitement$informatique,$pour$
retrouver$la$contribution$de$chaque$longueur$d’onde$au$flux.$Les$résultats$sont$les$mêmes$qu’avec$le$
spectrophotomètre$«$classique$»,$mais$les$temps$d’analyse$sont$fortement$réduits$et$la$précision$meilleure.$
!
II.2 L’absorbance : définition et mesure
M,./!(+%!',5(/.,+!LMO!9,+/%+#+/!(+%!L,(!45('.%()'O!%'4?9%L'O!9-.2.7(%L'O!9,5,)1%L'O!0.'',(/%L'O!0#+'!
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EGT>!
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I.1.a.i.1.1.1.1.1 I
BQRB!