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The 1955 AAS paper A. Walsh, "The application of atomic absorption spectra to chemical analysis", Spectrochimica Acta, 1955, 7, 108-117. Reprinted from.

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Presentation on theme: "The 1955 AAS paper A. Walsh, "The application of atomic absorption spectra to chemical analysis", Spectrochimica Acta, 1955, 7, 108-117. Reprinted from."— Presentation transcript:

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2 The 1955 AAS paper A. Walsh, "The application of atomic absorption spectra to chemical analysis", Spectrochimica Acta, 1955, 7, Reprinted from Spectrochimica Acta, Vol 7, A. Walsh, The application of atomic absorption spectra to chemical analysis, Pages , © (1955), with permission from Elsevier.

3 Constructivism: effective learning Engagement and understanding Link VCE physics (science) to topical events  2005 = 50th anniversary of paper of Victorian invention Multiple teachers running in the same direction Integrated curriculum  Themes crossing curriculum boundaries  Each discipline offers different insights

4 Electromagnetic spectrum: Figure 6.4, Brown, Lemay, Bursten, Burdge, Chemistry the Central Science (9e), Prentice-Hall, Electromagnetic spectrum Electromagnetic spectrum: Figure 6.4, Brown, Lemay, Bursten, Burdge, Chemistry the Central Science (9e), Prentice-Hall, 2003.

5 Light passing through a prism: Figure 6.10, Brown, Lemay, Bursten, Burdge, Chemistry the Central Science (9e), Prentice-Hall, Light passing through a prism

6 Sodium atomic emission spectrum

7 Solar spectrum: 400 to 700 nm Solar spectrum: N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF

8 Absorption spectroscopy Solar flare image: NSO/AURA/NSF Light source DetectorSample I out I init

9 Solar spectrum Solar spectrum: N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF

10 Atomic spectroscopy

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13 Boltzmann distribution Atomic energyMolecular energy WavelengthAtom N j /N 0 at 3000 K nmNa 5.88  nmCa 3.69  nmZn 5.58  nmCs 7.24  10 -3

14 Light sources Wide spectrum (thermal) light sources Narrow spectrum light sources Solar spectrum: N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF

15 Atomic spectroscopy Atomic emission  Zero background (noise) Atomic absorption  Bright background (noise)  Measure intensity change  More signal than emission  Trace detection

16 The 1955 AAS paper A. Walsh, "The application of atomic absorption spectra to chemical analysis", Spectrochimica Acta, 1955, 7, Reprinted from Spectrochimica Acta, Vol 7, A. Walsh, The application of atomic absorption spectra to chemical analysis, Pages , © (1955), with permission from Elsevier.

17 The 1955 AAS paper A. Walsh, "The application of atomic absorption spectra to chemical analysis", Spectrochimica Acta, 1955, 7,  Remove bright background >Hollow cathode lamp  Measure intensity change >Light chopper  Atomic spectra >Flame atomisation Photo of Sir Alan Walsh. © Australian Academy of Science. Reproduced from Historical Records of Australian Science vol. 13 (P. Hannaford, 2000) by permission of CSIRO Publishing and Australian Academy of Science.

18 Hollow cathode lamp Electron and ionic impact on cathode M(s)  M(g) M(g)    M*(g) M*(g)  M(g) + h The black "getter" spot Thin lay of cathode material Pictures of hollow cathode lamp, © Varian inc. Reproduced with permission from Varian Australia. low-pressure inert gas

19 Flame burner: D. C. Harris, Quantitative Chemical Analysis, 6th Edn., W.H. Freeman and Company, New York, 2002, from Figure Flame burner Flame burner: D. C. Harris, Quantitative Chemical Analysis, 6th Edn., W.H. Freeman and Company, New York, 2002, from Figure M n+ (aq) + anion(aq)  salt(s) salt(s)  salt(g) salt(g)  atoms (g) M*(g)  M(g) + hn

20 Light chopper Emission only

21 Light chopper Emission and transmitted light

22 Reprinted from Spectrochimica Acta Part B, Vol 54, A. Walsh, The development of the atomic absorption spectrophotometer, Pages , © (1999), with permission from Elsevier. The original 1954 AAS instrument

23 Reprinted from Spectrochimica Acta Part B, Vol 54, A. Walsh, The development of the atomic absorption spectrophotometer, Pages , © (1999), with permission from Elsevier. The first commercial prototype

24 Pictures of Varian AA280 flame instrument, © Varian inc. Reproduced with permission from Varian Australia. Hollow cathode lamps Modern commercial AAS instrument Flame atomiserSample inlet

25 Detection limits (ppm = ng mL -1 ) Data compiled by D. A. Skoog, D. M. West, F. J. Holler and S. R. Crouch, Fundamentals of Analytical Chemistry, 8th Edn., Brooks/Cole, Belmont (CA), 2004.

26 First-year chemistry exercise at Deakin University. Student determination of Fe Fe: 0.05 mg mL mL volumetric flasks 1.00 mL pipette 2 mL1 mL3 mL4 mL5 mL

27 Actual student data from first-year chemistry exercise at Deakin University. Student determination of Fe

28 Classroom use of atomic absorption AAS idea 3AAS idea 5 previewsreviews VCE topic AAS idea 4 VCE topic

29 VCE Physics Unit 1 (Light and waves) Key knowledge and skills  describe mathematically connections between wavelength, frequency, period and speed of travel of waves;  identify visible light as a particular region of a spectrum of transverse electromagnetic radiation;  describe the colour components of white light …;  describe colour dispersion in prisms and lenses

30 VCE Physics Unit 2 (Astrophysics) Light is the basic tool of astrophysicists and … the nature of the nuclear atom is the same throughout the Universe. Key knowledge and skills  describe characteristics of the Sun as a typical star, including size, mass, energy output, colour and information obtained from the Sun’s radiation spectrum;

31 VCE Physics Unit 4 (… light and matter) Outcome 1  On completion of this unit the student should be able to use wave and photon models to explain interactions of light and matter and the quantised energy levels of atoms. Key knowledge and skills  interpret atomic absorption and emission spectra in terms of a quantised energy level model of the atom, including calculations of the energy of photons …  E = hf

32 VCE Physics Unit 4 (3.2: Photonics) Key knowledge and skills  explain the production of light by incoherent light sources, in terms of >thermal motion of charged particles in materials for wide spectrum light sources, including the Sun… >transitions between quantised energy states of atoms for narrow spectrum light sources, including metal vapour lamps

33 VCE Chemistry Unit 3 (Analytical chem.) Key knowledge:  … analytical procedures … including … flame tests and … atomic absorption spectroscopy

34 Observations on metal concentrations in tilapia ( Oreochromis mossambicus ) in reservoirs of south Sri Lanka Reprinted from Ecotoxicology and Environmental Safety, Vol. 50, G. Allinson, et al., Observations on metal concentrations in tilapia ( Oreochromis mossambicus ) in reservoirs of south Sri Lanka, Pages , © ( 2002), with permission from Elsevier. Determination of Hg in fish Locations of the reservoirs from which tilapia samples were obtained. Cities: Cl, Colombo; G, Galle. Reservoirs: C, Chandrikewewa; R, Ridiyagama; M, Meegahanjandura; B, Badagiriya; K, Kirribanwewa.

35 c UN FAO PWTDI (Provisional Tolerable Weekly Intake). d UN FAO PMTDI (Provisional Maximum Tolerable Daily Intake). All calculations assume an average male adult body weight of 70 kg. Selected elements (  g) in 60 g tilapia Observations on metal concentrations in tilapia (Oreochromis mossambicus) in reservoirs of south Sri Lanka Reprinted from Ecotoxicology and Environmental Safety, Vol. 50, G. Allinson, et al., Observations on metal concentrations in tilapia ( Oreochromis mossambicus ) in reservoirs of south Sri Lanka, Pages , © ( 2002), with permission from Elsevier.

36 Observations on metal concentrations in tilapia ( Oreochromis mossambicus ) in reservoirs of south Sri Lanka  Average diet: 60 g tilapia day -1  Provisional tolerable weekly intake (PTWI) Hg ~15% of PTWI As ~6% of PTWI Cd < 0.1% of PWTI  Provisional maximum tolerable daily intake (PMTDI) Cu and Zn < 1% of PMTDI  ~ 15% of the required daily intake of Fe G. Allinson, M. Nishikawa, S. S. De Silva, L. J. B. Laurenson, and K. De Silva. Ecotoxicology and Environmental Safety, Vol. 50, pp (2002). Metal intake in Sri Lankan fish diet

37 VCE Math Methods Units 3, 4 This area of study will include:  Coordinate geometry >graphs of inverse functions derived from graphs of original functions;  Algebra >one-to-one and many-to-one functions, conditions for existence of inverse functions;

38 Calibration curves  Often curved  Linear if concentration range is carefully chosen Calibration curves

39 VCE Chemistry Unit 1 (Corrosion) This area of study will include:  reactions of metals in the atmosphere; corrosion of metals;  corrosion minimisation, including passive, sacrificial and cathodic measures.

40 Black "getter" spot  Material from anode  Reductant scavenges oxygen from lamp gas Hollow cathode lamp The black "getter" spot Thin lay of cathode material Pictures of hollow cathode lamp, © Varian inc. Reproduced with permission from Varian Australia.

41 Constructivism: effective learning Engagement and understanding Link VCE physics (science) to topical events  2005 = 50th anniversary of paper of Victorian invention Multiple teachers running in the same direction Integrated curriculum  Themes crossing curriculum boundaries  Each discipline offers different insights

42 Constructivism: effective learning Extends VCE Physics study design  Related to topics in VCE Physics SD  Extension topics >Critically evaluate knowledge >apply knowledge  Connections to other study designs >Reinforce/review learning >Deeper understanding

43 Acknowledgements Support, time release etc:  Deakin University  Loyola College, Watsonia

44 Permission to use material Thank you to:  Dr Graeme Allinson (Deakin University)  Australian Academy of Science  CSIRO Publishing  Elsevier  National Optical Astronomy Observatory / Association of Universities for Research in Astronomy / National Science Foundation (USA)  Varian Australia / Varian Inc.

45 Reading list A. Walsh, "The application of atomic absorption spectra to chemical analysis", Spectrochimica Acta, 1955, 7, A. Walsh, "The development of atomic absorption methods of elemental analysis ", Analytical Chemistry, 1991, 63, 933A-941A. A. Walsh, "The development of the atomic absorption spectrophotometer", Spectrochimica Acta Part B, 1999, 54, P. Hannaford, "Alan Walsh ", Historical Records of Australian Science, 2000, 13,

46 Reading list G. Allinson, M. Nishikawa, S.S. De Silva, L.J.B. Laurenson and K. De Silva, "Observations on metal concentrations in tilapia ( Oreochromis mossambicus ) in reservoirs of south Sri Lanka", Ecotoxicology and Environmental Safety, 2002, 51, D. A. Skoog, D. M. West, F. J. Holler and S. R. Crouch, Fundamentals of Analytical Chemistry, 8th Edn., Brooks/Cole, Belmont (CA), D. C. Harris, Quantitative Chemical Analysis, 6th Edn., W.H. Freeman and Company, New York, 2002.

47 Reading list More information about Australian science and scientists can be found at  Australian Academy of Science  Historical Records of Australian Science


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