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( )1 (PHOTOMETERS) 1. 2. 3. spectrophotometer. ( )2 Spectrophotometer Photometer Reflectance photometer Atomic absorption spectrophotometer Atomic emission.

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Presentation on theme: "( )1 (PHOTOMETERS) 1. 2. 3. spectrophotometer. ( )2 Spectrophotometer Photometer Reflectance photometer Atomic absorption spectrophotometer Atomic emission."— Presentation transcript:

1 ( )1 (PHOTOMETERS) spectrophotometer

2 ( )2 Spectrophotometer Photometer Reflectance photometer Atomic absorption spectrophotometer Atomic emission photometer Fluorescent photometer, Illuminometer, Chemiluminescent photometer Nephelometer / Turbidimeter (PHOTOMETERS)

3 ( )3 Electromagnetic energy or wave Wavelength( ) CommonSource of energy Over 25 cmRadio wavesElectron-spin orientation 0.4 – 25 cmMicrowaves (radar)Molecular rotation 25,000 – 4,000,000 nmFar Infrared Molecular vibration 25,000 – 25,000 nmTrue Infrared 800 – 2,500 nmNear Infrared 400 – 800 nmVisible light Valence electron transition 10 – 400 nmUltraviolet (UV) 0.1 – 10 nmSoft X-rays and X-raysInner-shell electron transition Less than 0.1 nmGamma rays (isotopes)Nuclear transition

4 ( )4

5 Viole t Blue Gree n Yello w Oran ge Red Green-yellow Yellow Red Blue Green- blue Green Visible Spectrum Approximated Wavelength (nm) Color of absorbed light Color of solution

6 ( )6 Incident Light [ I o ]Transmitted Light [ I t ] A = 2 - log %T Transmittance [T] = ItIt I0I0 %Transmittance [%T] = ItIt x 100 = 100T I0I0 Absorbance [A or O.D.] = log 1 = log I0I0 100 TItIt %T = log 1 – log T = - log T Absorbance [A or O.D.] = log 100 = log 100 – log %T %T

7 ( )7 b = ( cm ) Incident Light [ I 0 ] Transmitted Light [ I t ] C = b b bb * ( g%) A = a b C Beer and Lamberts Law ===> AC Ab C, b b, C

8 ( )8 a = absorptivity coefficient ( ) molar absorptivity L. mol -1. cm -1 molar absorptivity C mole/L A = a b C Beer and Lamberts Law ===>

9 ( ) Monochromator Energy Lamp Cuvette Photodetector Amplifier & Display device Grating Mirror Entrance Slit Exit Slit Interference filters Prism Grating Spectrophotometer Photometer

10 ( )10 Single beam spectrophotometer Split beam spectrophotometer Double beam spectrophotometer Beam Splitter or Half-mirror

11 ( )11 VIS spectrophotometer UV spectrophotometer UV/VIS spectrophotometer Tungsten filament lamp : nm Hydrogen/Deuterium lamp : nm Tungsten-halogen lamp : Xenon arc lamp : (Energy lamp)

12 ( )12

13 ( )13 MgF 2 Silver Glass Reinforced wave Interference filters Wave not Reinforced monochromater

14 ( )14 1 st -order spectrum 2 nd -order spectrum 3 rd -order spectrum Reverse-order spectrum Exit slit Entrance slit White Light Refraction Grating Spectrum pattern (linear scale)

15 ( )15 Near Infrareds light (NIR) Near UV light NIR Near UV Corn type prismLittrow type prism Glass prism spectrum pattern (log scale) Quartz prism spectrum pattern (log scale) Grating spectrum pattern (linear scale)

16 ( )16 Band pass is that range of wavelengths that pass through the exit slit of the wavelength selecting device. Band pass 100% peak height 50% peak height half-band pass Nominal band pass(width) and half-band pass(width) Radiant Energy Intensity Wavelength, nm

17 ( )17

18 ( )18

19 ( )19 cuvette Simple glass Special glass Plastic Quartz Flow-cell cuvette

20 ( )20 photodetector Photocell or Barrier layer cell or Photovoltaic cell Phototube Photomultiplier tube Photodiode Phototransistor Photodiode array

21 ( )21 Glass window Silver lacquer Semiconductor ( selenium, cadmium ) Metal base(iron) Photocell or Barrier layer cell or Photovoltaic cell -Selenium type , nm A - spectrophotometer bandpass - fatigue

22 ( )22 Glass envelope Photo cathode Anode Base volt dark current Phototube Photosensitive material cesium-antimony nm cesium oxide nm multialkaline ( Sb / K / Na / Cs ), photocell, fatigue, photocell

23 ( )23 Gas-filled phototube Photomultiplier tube : PMT

24 ( )24 PN PN PN PN PN PN PN N N P N Photodiode Phototransistor Photodiode array

25 ( )25 1. Very elevated concentrations are measured. 2. Incident radiant energy is not monochromatic. 3. The solvent absorption is significant compared to the solute absorbance. 4. Radiant energy is transmitted by other mechanisms(stray light). 5. The sides of the cell are not parallel. 6. The absorbance of a fluorescent solution is measured. Beers Law A = a b C

26 ( )26 Stray light 0% Stray light 1 % Stray light 5 % Absorbe ncy Concent ration Linearity 1% Stray light Linearity 5% Stray light

27 ( )27 Wavelength calibration Monochromator Energy Lamp Cuvette Photodetector Amplifier & Display device Grating Mirror Entrance Slit 630 nm

28 ( )28 Didymium filter : Peak => 585 nm Holmium oxide Peak(nm) Potassium dichromate solution g/L in 0.5 N KOH Peak=> nm Peak=> nm nm Oxyhemoglobin solution Red cell in 0.05% NH 4 OH Cobalt chloride solution 4.4 g/L in 1% HCl Peak=> nm

29 ( )29 Absorbance accuracy Potassium dichromate solution Copper sulfate solution Cobalt sulfate solution 120 mg/L in 0.01 N H 2 SO 4 4 g% in 1%H 2 SO 4 4 g% CoSO 4. (HN 4 ) 2 SO 4. 6H 2 O in 1%H 2 SO nm => Abs. 357 nm => Abs. 650 nm => Abs. 510 nm => 0.48 Abs. Neutral density filters

30 ( )30 Absorbance linearity Potassium dichromate solution in 0.5 N KOH Copper sulfate solution in 1%H 2 SO 4 0, 2, 3, 4, 5, 6, 7, 8, 9, 10 g%

31 ( )31 Stray light checking Stray light filter => 0 %T Abs. NaI 10g/l 220 nm NaNO 2 50 g/l 340 nm K 2 Cr 2 O g/l in 0.05 N KOH 370 nm K 2 Cr 2 O g/l in 0.05 N KOH 400 nm CuSO g/l 680 nm * Stray light 1%T

32 ( )32 Light Source Photo detector Readout device Sample surface Reflectance photometer

33 ( )33 Reflection density (D R ) = Log ( R O / R test ) R O = Intensity of light reflected by standard reflector R test = Intensity of light reflected by test sample Barium sulface-coated surface A = log ( 1 / T ) or A = log ( I o / I t ) Transmittion density / Absorption / Opitical density

34 ( )34 Kubelka-Munk-Theory R is the absolute reflectance of sampled layer k is the molar absorption coefficient of the sample surface s is the scattering coefficient of the sample surface The theory works best for optically thick materials where >50% of light is reflected and <20% of light is transmitted. dXdX X x iTiT iRiR Backing Reflectance Paper Reflectance I0I0 IRIR

35 ( )35 Vaporized atoms in the group state (A o ) absorb light at very narrowly defined wavelengths. [ nm ] A + vapor + e > A o vapor Compounds ( A + Cl - ) heat hv A* vapor Ground state Excited state ( unstable ) hv heat Combustion process Oxygen Oxide High temperature

36 ( )36 Hollow- cathode lamp Chopper Burner Monochromator Photomultiplier tube Readout device Sample solution Atomization = convert chemicals to atomic vapor Nebulization= convert solution to a fine spray or aerosol Burner Line spectrum light Atomic absorption spectrophotometer Hollow cathode lamp

37 ( )37

38 ( )38 Electrodes Discharge Lamp (EDL) Hollow cathode lamp Volt Volt Specific metal Specific metal salt Inert gas Electrical coil Inert gas Energy lamp for Atomic absorption spectrophotometer

39 ( )39 Burner head Fuel gas Oxidant Sample capillary Nebulizer Nebulizer oxidant Flow spoiler Flow spoiler retaining screw Nebulizer adjusting knob Burner head locking ring Pressure relief vents To waste Type of burnerTotal consumption burner Premix burner ( laminar-flow burner )

40 ( )40 Hollow- cathode lamp Chopper Burner Monochromator Photomultiplier tube Readout device Sample solution Line spectrum light Emission interference A o + heat > A* hv 80%20% emission interference

41 ( )41 Flame atomic absorption spectrophotometer Flameless atomic absorption spectrophotometer Hydride generated atomic absorption spectrophotometer HgH 2 Hollow- cathode lamp Chopper Monochromator Photomultiplier tube Readout device Sample solution Line spectrum light Hydride generator Carrier gas Cell Temperature up to 2,300 o C

42 ( )42 Hollow- cathode lamp Chopper Monochromator Photomultiplier tube Readout device Sample solution apply to Line spectrum light High Voltage apply ( temperature up to 2,700 o C ) Graphite furnace atomic absorption spectrophotometer Platform or tube made form carbon

43 ( )43 Burner Wavelength selector( filters) Photomulti plier tube Readout device Sample solution Emission light Na / K / Ca Atomic emission photometer

44 ( )44 Direct type and Internal standard type of flame photometer Internal standard : lithium or cesium Sample and standard are diluted with a constant concentration of internal standard Readout device burner filters detectors Coincident device

45 ( )45 Scattered Absorbed Transmitted Light No loss of energy No change of energy same wavelength before and after it interacts with the matter Energy loss Some energy loss and Reemitted light Fluorescence and Phosphorescence Fluorescent photometer Illuminometer or Chemiluminescent photometer

46 ( )46 First monochromator Second monochromator Light source Excitation slit Emission slit Sample in cuvette Detector Readout device Fluorescent photometer or Fluorometer

47 ( )47 Illuminometer or Chemiluminescent photometer monochromator Emission slit Sample in cuvette Readout device Photo Detector Luminol (5-amino 2,3-dihydro-1,4-phthalazinedione) peroxidase hv nm Luciferin ( 6-hydroxybenzothiazole ) Oxidized Luminol Enhancer Intensity emitted light Low intensity

48 ( )48 Particle diameters of Antigen-antibodies complex : ,500 nm => nm = Light source Collimating len Slit Filter Sample Cuvette Stray light traps Detector Signal q Monochromator Nephelometer : Turbidimeter :


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