Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am)
TP AtomXthathasanorangeemissionline 650nm withphotonenergy
Eorange hc/ 650nm andagreenemissionline 510nm withphotonenergy
Egreen hc/ 510nm .Whichofthefollowingstatementsaretrueabouta
singleemissionprocessofatomX?
20%
20%
20%
20%
20%
1.
2.
3.
4.
5.
Wednesday, November 16, 2016
• Complete:Naturalfrequenciesofatoms
• Lightandmatterexchangeenergysmoothlyandslowly,
http://goo.gl/Ac4HGM
• Lightenergyisexchangedintinyamountscalledphotons
• Energydiagramsfromlight‐matterresonance
AnatomofXcanemitlightwithanyamountofenergy.
AnatomofXcanemitlightwithenergybetweenEorange andEgreen.
AnatomofXcanemitlightinmultiplesofEorange orEgreen.
AnatomofXcanemitlightonlyofEorange orEgreen.
Noneoftheabove.
Nextlecture: Electronwavesandquantization
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Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
What are natural frequencies of atoms?
Hatomemissionspectrum
20%
20%
20%
20%
20%
8
Copyright © 2016 Dan Dill [email protected]
Copyright © 2016 Dan Dill [email protected]
TP AtomXthathasanorangeemissionline 650nm withphotonenergy
Eorange hc/ 650nm andagreenemissionline 510nm withphotonenergy
Egreen hc/ 510nm .Whichofthefollowingstatementsaretrueabouta
singleemissionprocessofatomX?
1.
2.
3.
4.
5.
AnatomofXcanemitlightwithanyamountofenergy.
AnatomofXcanemitlightwithenergybetweenEorange andEgreen.
AnatomofXcanemitlightinmultiplesofEorange orEgreen.
AnatomofXcanemitlightonlyofEorange orEgreen.
Noneoftheabove.
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1
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
TP TheredlightemittedbyHatomshasfrequency4 1014 Hz.TheIR
C‐Ostretch,duetotheoscillationofprotonsandneutrons nuclei ,hasa
frequencyof~1 1013 Hz.Thismeansthat,comparedtothemovingmassin
visiblespectra,matom,themovingmassinIRspectra,mIR,is
What are natural frequencies of atoms?
Hatomemissionspectrum
Theredlightemittedhasfrequency4 1014 Hz.IRlight,duetotheoscillation
ofprotonsandneutrons nuclei ,hasafrequencyof~1 1013 Hz.
25%
25%
25%
25%
1.
2.
3.
4.
~15timesheavier
~150timesheavier
~1,500timesheavier
~15,000timesheavier
EstimatetheratioofthemassoftheobjectoscillatinginHatomthatleadsto
theemissionofvisiblelight,relativetothemassofaproton.
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Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
11
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
What are natural frequencies of atoms?
What are natural frequencies of atoms?
Hatomemissionspectrum
Hatomemissionspectrum
Theredlightemittedhasfrequency4 1014 Hz.IRlight,duetotheoscillation
ofprotonsandneutrons nuclei ,hasafrequencyof~1 1013 Hz.
Theredlightemittedhasfrequency4 1014 Hz.IRlight,duetotheoscillation
ofprotonsandneutrons nuclei ,hasafrequencyof~1 1013 Hz.
EstimatetheratioofthemassoftheobjectoscillatinginHatomthatleadsto
theemissionofvisiblelight,relativetothemassofaproton.
EstimatetheratioofthemassoftheobjectoscillatinginHatomthatleadsto
theemissionofvisiblelight,relativetothemassofaproton.
νatom/νIR ~40 √ mIR/matom
mIR/matom ~402 somIR is~1600timesheavierthanmatom
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Copyright © 2016 Dan Dill [email protected]
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2
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
What are natural frequencies of atoms?
Hatomemissionspectrum
Lightandmatterexchangeenergysmoothlyandslowly
Theredlightemittedhasfrequency4 1014 Hz.IRlight,duetotheoscillation
ofprotonsandneutrons nuclei ,hasafrequencyof~1 1013 Hz.
EstimatetheratioofthemassoftheobjectoscillatinginHatomthatleadsto
theemissionofvisiblelight,relativetothemassofaproton.
MotionisIRduetoatoms,motioninatomsduetoelectronclouds.
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Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
15
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Resonant tugs by light on an electron cloud
Non-resonant tugs by light on an electron cloud
http://goo.gl/Ac4HGM
http://goo.gl/Ac4HGM
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Copyright © 2016 Dan Dill [email protected]
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3
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Resonant tugs by light on an electron cloud
Eachoscillationtakesabout1/ ~10
14seconds
Light energy is exchanged in tiny amounts called photons
About100,000oscillationsarerequiredtocompletethetransformation
Soabout10
9
secondarerequiredtotransformthe1scloudintothe2pcloud.
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Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Total energy exchanged is h
Copyright © 2016 Dan Dill [email protected]
light
= h c / λlight
33
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
ΔElight + ΔEatom = 0
Thisamountenergyiscalledaphoton.
Photonenergyunitsareexchanged betweenlightandatoms
ΔElight ΔEatom 0
Emissionoflight:
Lightgains aphotonof energy,ΔElight h c/λ
Atom electroncloudloses energy,ΔEatom –h c/λ
Absorptionoflight:
Lightloses aphotonof energy,ΔElight –h c/λ
Atom electroncloudgains energy,ΔEatom h c/λ
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Copyright © 2016 Dan Dill [email protected]
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4
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
ΔElight + ΔEatom = 0
Energy diagrams from light-matter resonance
Photonenergyunitsareexchanged betweenlightandatoms
Thevisiblespectrumofhydrogengasdischargeis
ΔElight ΔEatom 0
Sketchtheenergydiagramoftheatomcorrespondingtoemission ofbluelight,
λblue 420nm.
Onthesameenergyaxis,addtheenergydiagramcorrespondingtotheatom
thenabsorbing ofredlight,λred 710nm.
Whyistheirnoemissionat600nm?
Hint:ThinkaboutwhyIRabsorptionlinesoccuratparticularwavenumbers?
40
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Quiz Ontheatomenergydiagram,arrowsrepresentpossiblephotonenergies.
Whicharrowscorrespondtolightabsorbed bytheatom?
14%
14%
14%
14%
14%
14%
14%
1.
2.
3.
4.
5.
6.
7.
OnlyA
OnlyB
OnlyC
OnlyAandB
OnlyBandC
A,B,andC
Noneoftheabove
44
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Energy diagrams from light-matter resonance
Thevisiblespectrumofhydrogengasdischargeis
C
E
B
Linesoccuronlywhenlight atom,i.e.,whenthefrequencyofoscillationofthe
electricfieldofthelightmatchesapossiblenaturalfrequency frequencyofthe
“jiggling” oftheatomelectroncloud.
A
Sincelight Ephoton /h andsinceEphoton |ΔEatom| |Ef – Ei|…
atom |Ef – Ei|/h
Thereforeinteractionhappensonlywhen…
Ephoton |Ef – Ei|
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Copyright © 2016 Dan Dill [email protected]
46
5
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Energy diagrams from light-matter resonance
1 eV = energy of electron in a field of 1 V = 1 J/C
Thevisiblespectrumofhydrogengasdischargeis
energy charge voltage
e 1.6021766 10
eV e
C
19
1J/C 1.6021766 10
19
J
Ephoton h light
Recipetomaketheenergydiagramthataccountsforthisspectrum.
1.Getlinesvalues:656.3nm,486.1nm,434.1nm,and410.2nm.
hc/ 656.3nm 2.ExpressenergiesineV.
3.027 10
19
J
1eV
1.6021766 10
19J
1.889eV
47
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
48
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Energy diagrams from light-matter resonance
Energy diagrams from light-matter resonance
Thevisiblespectrumofhydrogengasdischargeis
Thevisiblespectrumofhydrogengasdischargeis
Recipetomaketheenergydiagramthataccountsforthisspectrum.
Recipetomaketheenergydiagramthataccountsforthisspectrum.
1.Getlinesvalues:656.3nm,486.1nm,434.1nm,and410.2nm.
1.Linesat656.3nm,486.1nm,434.1nm,and410.2nm
2.ExpressenergiesineV:1.889eV,2.551eV,2.856eV,3.023eV
2.ExpressenergiesineV:1.889eV,2.551eV,2.856eV,3.023eV
3.Emissionmeansenergygivenoffbyatom,sodownwardarrows.
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Copyright © 2016 Dan Dill [email protected]
50
6
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:14 PM
Copyright © 2016 Dan Dill [email protected]
Lecture 29 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Energy diagrams from light-matter resonance
Energy diagrams from light-matter resonance
Thevisiblespectrumofhydrogengasdischargeis
Thevisiblespectrumofhydrogengasdischargeis
Recipetomaketheenergydiagramthataccountsforthisspectrum.
Recipetomaketheenergydiagramthataccountsforthisspectrum.
1.Linesat656.3nm,486.1nm,434.1nm,and410.2nm
Carryoutthisrecipeathome,makingdiagramtoscale,inyournotes.
2.ExpressenergiesineV:1.889eV,2.551eV,2.856eV,3.023eV
3.Emissionmeansenergygivenoffbyatom,sodownwardarrows.
4.Assumeallarrowendatthesameplace.
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Copyright © 2016 Dan Dill [email protected]
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