仪器分析英文课件ChapterComponentsofOpticalInstruments.pptVIP

* * Chapter 3. Components of Optical Instruments §1 General designs of optical instruments Phenomena for optical spectroscopic methods Absorption Fluorescence Phosphorescence Scattering Emission Chemiluminescence Source container Wavelength selector Radiation detector Signal processor and readout Three configurations Components of typical spectroscopic instruments Source lamp Or heated solid Sample holder Wavelength selector Photoelectric transducer Signal processor and readout (1) (2) (3) (4) (5) hv hv hv I Source lamp Or heated solid Sample holder Wavelength selector Photoelectric transducer Signal processor and readout (1) (2) (3) (4) (5) hv hv hv I Source and Sample holder Wavelength selector Photoelectric transducer Signal processor and readout (1) and (2) (3) (4) (5) hv hv I A. absorption B. fluorescence, phosphorescence, scattering C. emission, chemiluminescence Sources for spectroscopic instruments §2 Sources of radiation Enough Energy Stability Continuum Sources Line Sources Laser Sources Light Amplification by Stimulated Emission of Radiation Advantages ? intense ? monochromatic (narrow bandwidths)(line sources) ? pulsed (10-15-10-6 s) or continuous wave (cw) ? coherent nature of outputs ? small beam divergence §3 Wavelength Selectors For spectroscopic analysis, a limited, narrow, continuous group of wavelength is required. 干涉光劈 Fig. 7-11 Output of a typical wavelength selector (p.155) Filters monochromators Two types of wavelength selectors Filters b. Absorption filter - colored glass or dye between two glass plates a. Interference filter - two thin sheets of metal sandwiched between glass plates, separated by transparent material (Interference for transmitted wave through 1st layer and reflected from 2nd layer ) Wavelength (nm) Transmittance 0 100 400 750 Band pass interference filter Transmittance 0 100 Useful in non-scanned situations and when a specific, known band of radiation needs to be monitored. Band-reject interference filter Five compo