New NAME NAME Spectra · 2012. 1. 17. · Printed: Apr/20/2009 Activity: Spectra Page IA- 3 ©2009...

Printed: Apr/20/2009 Activity: Spectra Page IA- 1

©2009 W. Pezzaglia Astronomy Lab Manual Updated:2009Apr20

NAME_______________ NAME__________________ __________________ NAME_______________ NAME__________________ __________________

Spectra

Project Star Spectroscope (Learning Technologies)

Equipment:

• Plastic Spectroscopes (Learning Technologies, Project STAR) • Vernier Spectroscopes (with grating or prism for detailed measurements) • Color Filter Set (red, yellow, green, blue, violet, interference) • Red Laser • Spectra Tubes

o Known spectra:Hydrogen, Helium, Sodium, Mercury, Neon, and others o Some unknown sources

• Fluorescent light • Incandescent Light with variable power supply

References o Spectra Demo: http://jersey.uoregon.edu/elements/Elements.html o Spectroscopes:

http://www.sciproj.com/FeaturedVendorProduct.aspx?uid=72438 o Some good pictures of spectra through this scope:

http://home.comcast.net/%7emcculloch-brown/astro/spectrostar.html

Page IA- 2 Spectra Printed Apr/20/2009


Table of Contents I. Introduction (in class) II. Theory (very rough notes)

A. Black Body Radiation (Stefan and Wien Law) B. Spectra Types (Kirchhoff’s Laws) C. Atomic Spectra

III. Lab Activities

Part A White Light 1. White Light at full power 2. Change in Temperature 3. Filtered White Light

Part B: Spectra Observation 1. Known Spectra 2. Fluorescent Light 3. Unknown Spectra 4. Data Sheet #1 (Known Spectra) 5. Data Sheet #2 (Unknown Spectra)

Part C: Laser Light 1. Predictions 2. Experiment 3. Conclusion

Part D: Fraunhofer Spectra 1. Observation 2. Table of Fraunhofer Lines 3. Table of Solar Abundances

Its possible not all of the above will be assigned. Be sure to read the assignment as given on the board!



II. Theory (more given in lecture) A. Black Body Radiation

1b. Josef Stefan’s Law 1879• Experimentally shows total output of

light of a hot dense (black) body is proportional to 4th power of the temperature (in Kelvin)

• Power (watts)=AσT4

• σ=5.67x10-8 Watts/(m2-K4)• A=surface area

• 1884 Ludwig Boltzmann (formerstudent of Stefan) derives formulafrom thermodynamics.

• I was a guest speaker (Sept 2005) at theJosef Stefan Institute in Slovenia.

31

2a. Wien’s Displacement Law• 1893 shows that the “color” of black

body is inversely proportional to temperature.

• λ = α/T• Wien’s constant

α= 2,898,000 nm-K• So T=6000ºK gives

λ=483 nm

33



B. Types of Spectra: Kirchhoff’s Laws

2b. Gustav R Kirchhoff (1860)50

His three laws:1. A hot dense body will emit a

continuous spectrum2. A hot transparent gas will emit

emission line spectrum3. A cool transparent gas in front of a

source of continuous spectrum will produce absorption spectra.

2a. Kirchhoff’s Laws 49



C. Atomic Spectra (Bohr’s Model of Atom)

3a. Rydberg Formula 33

• 1885 Balmer comes up with formula that explains the Hydrogen lines (“Balmer Series”)

• 1888 Rydberg improves formula, where n1=2, n2={3,4,5}

•1895 Paschan Series discovered in IR, described by n1=3•1908 Lyman Series discovered in UV, described by n1=1

3g. Spectral Series 58



III. Lab Activities Part A: White Light 1. White Light Observation (full power)

• View spectra of white light under full power (120 volts)

• For each “color” determine the “center” wavelength (in nm)

• Next estimate the start/end borders between the colors (e.g. the end of green should be the start of yellow)

• Calculate the for each color the: Width = End-Start

Color Start Center End Width Violet Indigo Blue Green Yellow Orange Red

(a) How far into the Violet (near UV) can you see before it drops off? __________ nm

(b) How far into the Red (near Infrared) can you see before it drops off?__________ nm

(c). Which “color” is the narrowest band? ___________________________

(d). Which “color” is the widest band? ___________________________

(e) Summarize: Does the white light extend as deep into the violet(red) as the most violet(red) line seen in the other spectra? [You’ll need to do part B before answering this question]



2. Change In Temperature • Lower the Power to 20% (should we change this value?)

• Notice the change in the white light spectra.

(a) Summarize: Describe the change in the spectra (quantify any change in range, and intensities of colors, e.g. does yellow drop less than blue).

(b) Center: For full power, and 20% power, estimate the “center” wavelength of the spectra. Does this center shift at all? In what direction?

(c) Interpret what you see in terms of Wien’s Law and Stephan Boltzmann law.

3. Filtered White Light (a) View white light after it has passed through colored glass filters. Summarize the filter’s effect (be

quantitative, for example, it passes 400 nm through 500 nm and blocks the rest).

(b) Interference Filter: If one is available, summarize its effect.



Part B: Spectra (Datasheet #1 & 2) WARNING: DANGEROUSLY HIGH VOLTAGE IS APPLIED TO THE SPECTRA TUBES

There will be a number of spectra sources set up for you to observe using a hand-held spectroscope. Half of them will be “known”, the other half “unknown” for which you will try to identify the elements from the “known” sources.

Question B-1 Known Spectra (Data Sheet #1) Arc tubes will be set up (probably Hydrogen, Mercury, Neon, Sodium and Helium), most of them displaying emission spectra. For each, on Data Sheet #1:

• Label the element name • Note the “visual” color of the tube (what color it appears to your eye) • Sketch the spectra lines seen (accurately on the scale) • Classify the spectra type (Emission, Absorption, Continuous)

(a) Calibration on Hydrogen: Your spectroscope scale may not be completely accurate. The expected lines of Hydrogen are red (656 nm), blue (486 nm), indigo (434 nm) and violet (410 nm). Do you see all of these lines? Are the wavelengths you measured right on, or consistently low/high?

(b) With the naked eye, note the color of each tube. Is this color consistent with the spectral lines seen (are there any surprises, for example appears yellow, but really it only has red and green lines)?

(c) Are all the spectra of type “emission”? Are any continuous or show absorption?

(d) Do any of the tubes have a violet line which exceeds that found in white light? Do any have a red line which exceeds than found in white light?



Question B-2 Fluorescent Light (Data Sheet #2) As your first “unknown”, view the spectra of a Fluorescent light. Sketch its spectra structure in the lower part of DataSheet#2. (a) What type of spectra structure does this display? (Emission, Continuous, Absorption)

(b) To the naked eye, a Fluorescent light appears “white”. Where does this come from (i.e. are there any “white” lines in the spectra)?

(c) Comparing the spectra to the “known” sources, can you identify which element is present in a Fluorescent light? Specifically, which lines match (give wavelengths & colors)?

Question B-3 Other Unknown Spectra (Data Sheet #2) Your lab instructor will have a number of other “unknown” sources for you to view. For each, sketch the spectra and answer the question(s) below. These sources may include (all are different)

• White Computer Screen • Red, green and blue on computer screen • Building lights, streetlights (if dark!) • Vending Machine

(a) What type of spectra structure does each display? (Emission, Continuous, Absorption)

(b) Again, consider the naked eye color, and see if you can make sense of it from the components in the spectra. Note some of these sources (n.b. the Coke Machine) may be passing through a colored glass filter (i.e. is the spectra really red, or is it white light passing through red glass)?

(c) Comparing the spectra to the “known” sources, can you identify which element is present in each of these unknowns?



Spectra Data Sheet #1 KNOWN SPECTRA Name__________________ Element=________________ Visual Color=__________ Spectra Type=_______

Element=________________ Visual Color=__________ Spectra Type=_______







Spectra Data Sheet #2 UNKNOWN SPECTRA Name__________________ Object=Fluorescent light Visual Color=__________ Spectra Type=_______

Object=________________ Visual Color=__________ Spectra Type=_______







Part C: Laser Light 1. Prediction/hypothesis: Before doing an experiment, make a prediction!

(a) Red Filter: If you shine red laser light through a red filter what do you think will happen?

(a) Yellow Filter: How about through a Yellow Filter? Explain your reasoning!

(c) Green Filter How about through a green Filter? Explain your reasoning!

(d) Blue Filter How about through a blue Filter? Explain your reasoning!



2. Experiment: Now actually do the experiment. (a) Red Filter: What happened? Did it match your expectations?

(b) Yellow Filter: What happened? Did it match your expectations?

(c) Green Filter What happened? Did it match your expectations?!

(d) Blue Filter What happened? Did it match your expectations?

3. Conclusion: Summarize what is happening when you shine a red laser light through a filter.



Part D: Fraunhofer Spectra Question E-1 Fraunhofer Lines WARNING: DO NOT POINT SPECTROSCOPE DIRECTLY AT THE SUN unless its setting/rising. Instead point it at blue sky or the sunlight through a tree or other obscuring device. You should be able to see many of the Fraunhofer absorption lines (the ones with Capitol letters), but not all of them (e.g. the ones with small letters).

(a) Data: Sketch all the Fraunhofer (absorption) lines seen in the scale below..

Blue Sky=________________ Visual Color=__________ Spectra Type=_______

(b) Compare your observations with the table provided. Summarize which Fraunhofer lines you could see, include their wavelengths, and compare to the values listed in the table. You probably saw some of the lines with CAPITOL letters (e.g. C and D lines), but not many of the others.

(c) Do the Fraunhofer lines that you most easily see correspond to elements which are most common in the solar system? [Refer to “Solar Abundance” table]

204

TABLE 50- PRINCIPLE FRAUNHOFER LINES

Line

Name*Wavelength

0

A (A)

Color Element Notes

A 7621,7594 Deep Red O2 Band in extreme red, sharplyqefined on side towards violet,due to terrestrial oxygen.

?68676563

aBC

RedRedRed

H2OO2H

°1,2E2

El

5896,5890 Orange-Yellow Na

Narrow Band, Terrestrial Water Vapor.Band similar to A, Terrestrial OxygenBalmer H Line (solar).

C1

Double Balmer Sodium Line (solar).

52705183

GreenGreen

FeCa

Close group of lines due to Iron,and Calcium (solar)

b1b2b3b4

5184517351685167

GreenGreenGreenGreen

MgMgFeMg

Close group of lines due to SolarMagnesium and Iron

F 4861 Blue-Violet H

G VioletVioletVioletViolet

Balmer H~ Line (solar).

Composite Band, include solar:Balmer Hy LineCalciumIron

G1

G1G2

43404307.74307.9

HCaFe

4227410239683934

Extreme VioletExtreme VioletExtreme VioletExtreme Violet

9hHK

CaHCaCa

CalciumBalmer Hn Line (solar).Very BroddVery Broad (Not seen by Fraunhofer).

3820372735813441336132873179,318131003048302129942948

LMN0pQR

51 25 '

TtU

uvuvuvuvuvuvuvuvuvuvuvuv

FeFeFeFeTiFeCaFeFeFeFeFe

Titanium

Double Calcium line 0Triple Line, spacing 0.4 A

IS-:;Z-

~50-7

205

TABLE SO-II ELEMENTS AND SOLAR ABUNDANCES.

AtomicNumber

AtomicaWelghtSymbol Name

Solar Abundanceb(Relative to Hydrogen=1012)

12345

6789

10

11121314151617181920

2122232425

2627282930

3132333435

3637383940

HHeLiBeB

CN0FNe

NaMgAlSiP

SClArKCa

ScTiVCrMn

FeCoNiCuZn

GaGeAsSeBr

KrRbSryZr

hydrogenheliumlithiumberylliumboron

carbonnitrogenoxygenfluorineneon

sodium,magnesiumaluminumsilic,onphosphorus

sulphurchlorineargonpotassiumcalcium

scandiumtitaniumvanadiumchromiummanganese

.ironcobaltnickelcopperzinc

galliumgermaniumarsenicseleniumbromine

kryptonrubidiumstrorJtiumyttriumzirconium

;1..01

4.00

6.949.()1

10.81

12.01

14.01

16.00

19.0020.18

2~.9924.3126.9828.09

30.97

32.06

35.45

39.95

3,9.1040.08

44.9647.90

510.9452.00

54.94

55.8558.93

58.716,3.5565.37

69.7212.5914.92

18.9679.90

83.8085.4787.6288.9191.22

10126.3 x 101010 X 101

1.4 X 1011.3 X 102

4.2 X 1088.7 X 1076.9 X 1083.6 x 1043.7 X 107

1.9 X 1064.0 X 1073.3 X 1064.5 X 1073.2 X 105

1.6 X 1073.2 X 1051.0 X 1061.4 X 1052.2 X 106

1.1 X 1031.1 x 1051.0 X 1045.1 X 1052.6 X 105

3.2 X 1077.9 X 1041.9 X 1061.1 X 1042.8 X 104

6.3 X 1023.2 X 103

4.0 X 1027.9 X 1021.3 x 1025.6 X 102

50-8

206

AtomicaWeight

AtomicNumber Symbol .Name

Solar AbundanceJ(Relative to Hydrogen=lO12)

4142434445

4647484950

5152535455

5657585960

6162636465

6667686970

7172737475

7677787980

8182838485

NbMoTcRuRh

PdAgCdInSn

SbTeIXeCs

BaLaCePrNd

PmSmEuGdTb

DyHoEr1mYb

LuHfTaW

Re

asIrptAuHgT1PbBiPoAt

92.9195.9498.91

1011.07102.91

106.4107.8711'2. 40114.82118.69

1211.75127.60126.90131.30132.91

137.34138.91140.12140.91144.24

146150.4151.96157.25158.93

162.50164.93167.261Q8.93110.04

174.97178.49180.95183.851$6.2

190.2192.2195.09196.97200.59

204.37207.19208.9821102'10

7.9 X 1011.4 X 102

6.8 X 1012.5 X 101

3.2 X 1017.17.1 x 1014.5 X 1011.0 X 102

1.0 X 101

niobiummolybdenumtechnetiumrutheniumrhodium

palladiumsilvercadmiumindiumtin

antimonytelluriumiodinexenoncaesium

bariumlanthanumceriumpraseodymiumneodymiumprome!thi urnsamariumeuropiumgadoliniumterbium

dysprosiumholmiumerbiumthuliumytterbium1 ute1: i urnhafnii urntantalumtung~;tenrhenium

osmi IJmiridiump 1 at'i num

goldmercurythalliumleadbismuthpoloniumastatine

<7.9 X 101

1.2 X 1021.3 x 1013.5 X 1014.61.7 x 101

5.25.01.3 x 101

1.1 X 101

5.81.87.9

5.86.3

5.0 X 101<0.5

5.07.15.6 x 1015.6

<1.3 x 102

7.98.5 x 101

<7.9 X 101

50-9

tf1

207.:.

AtomicaWeight

AtomicNumber Symbol Name

Solar Abundance(Relative to Hydrogen=1012)

8687888990919293949596979899

100101102103104105106

RnFrRaAcTh

PaUNpPuAm

CmBkCfEsFm

MdNoLrRfHa

radon 222francium 223radi IJm 226.03actinium 227thorium 232.04

protactinium 230.04uranium 238.03neptlJni urn 237.05plutonium 242americium 242

curium 245berkt~ 1 i urn 248californium 252ei ns.tei ni urn 253fermium 257

mendelevium 257nobelium 255lawrencium 256rutherfordium 261hahnium 262

(Reported 1974) 263

aAtomic weights are averages for terrestrial abundances.

bThe solar abundance for hydrogen has been arbitrarily set at 1012.

Reference: Solar abundances from John E. Ross and Lawrence H. Aller,Science, 191, 1223, 1976. Gaps indicate that the element has not beenobserved on the sun.

I~b~ 50-10

New NAME NAME Spectra · 2012. 1. 17. · Printed: Apr/20/2009 Activity: Spectra Page IA- 3 ©2009...

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Transcript of New NAME NAME Spectra · 2012. 1. 17. · Printed: Apr/20/2009 Activity: Spectra Page IA- 3 ©2009...