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Spectrochemical Instrumentation Modules

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Presentation on theme: "Spectrochemical Instrumentation Modules"— Presentation transcript:

1 Spectrochemical Instrumentation Modules
1. Light Source 2. Optical Components 3. Sampling Device 4. Wavelength Selector 5. Detector 6. Signal Processor

2 Spectrochemical Instrumentation Modules

3 Spectroscopic Light Sources
1. Continuum Sources 2. Line Sources 3. Quasi-continuum Sources

4 Source Types

5 Source Characteristics

6 Continuum Sources Emit radiation over a broad spectral range.
Continuum in Wavelength, not necessarily in time. Most of these are “black body emitters. The spectral range depends upon the temperature of the black body.

7 Spectral Radiance of a Black Body

8 Continuum Sources

9 Continuum Sources

10 Nernst Glower

11 Globars

12 Tungsten Lamps

13 Hydrogen or Deuterium Lamp
Current through low pressure H2 or D2 Fused silica window nm

14 Xenon Lamps Pass current through high pressure Xenon Gas
nm output, sapphire window Provide high intensity, but with high noise

15 Line Sources Emit intense radiation over a narrow spectral range (or line). The Full Width at Half Maximum (FWHM) for these sources is: FWHM ≤ 0.01 nm

16 Typical of Line Sources
1. Low pressure pen lamps (Hg pen lamp) 2. Hollow Cathode Lamp (HCL) 3. Electrode-less Discharge Lamp (EDL)

17 Pen Lamps Low pressure metal vapor inside an electrical discharge
Spectra characteristic of the metal vapor Often used for calibration purposes

18 Hg Calibration Spectrum

19 Hollow Cathode Lamps Cylindrical Cathode containing metal of interest
Low pressure inert gas atmosphere Produces spectrum of cathode metal

20 Hollow Cathode Lamp Spectrum

21 Electrode Discharge Lamps
Metal salt in inert atmosphere Atomized and excited by RF field 10 x stronger than HCL for volatile metals

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