Components of Optical Instruments or What’s inside that spectrometer?

Components of Optical Instruments Emission Flame Photometer Flame Atomic Absorption Spectrometer Absorption Spectrometer Fluorescence and/or Scattering Spectrometer SourceWavelength SelectorSampleDetector Signal Processor Readout

Components of Optical Instruments Emission Flame Photometer SourceWavelength Selector Sample Detector Signal Processor Readout

Components of Optical Instruments Flame Atomic Absorption Spectrometer SourceWavelength Selector Sample Detector Signal Processor Readout

Components of Optical Instruments Absorption Spectrometer SourceWavelength SelectorDetector Signal Processor Readout Sample

Components of Optical Instruments Fluorescence and/or Scattering Spectrometer Source Wavelength SelectorDetector Signal Processor Readout Sample 0-90 o

Components of Optical Instruments Fig. 7-2, pg. 145 ”(a) Construction materials

Components of Optical Instruments Fig. 7-2, pg. 145 ”(b) wavelength selectors for spectroscopic instruments."

Components of Optical Instruments

Sources YOU TELL ME!

Sources of radiation Blackbody Radiation: I

Monochromator – can vary wavelength – scan spectrum Prism – shorter wavelengths dispersed more

Grating – Dispersion of light is linear in

Types of gratings – most common – echellette UV-visible  1200 –1400 grooves /mm IR  hundreds of grooves/mm Holographic Gratings – made by laser technology – very cheap, easy to make and very reproducible, can produce up too 6000 grooves/mm.

Width of Slits

Effective Bandwidth –  eff = wD -1 reciprocal linear dispersion, the inverse of the linear dispersion (D, mm/nm), which is the spreading of the light by a monochromator grating. d is the distance between blazes on the grating, and F is the focal length of the monochromator. w= slitwidth when Dy = w,  is the effective bandwidth

Example: To tell the difference between and nm light, what slitwidth would be required?