1 / 9

FT-IR Instrument

FT-IR Instrument. Components. Source Michelson Interferometer Sample Detector. Sources. Black body radiators Inert solids resistively heated to 1500-2200 K Max radiation between 5000-5900 cm -1 (2-1.7 m m), falls off to about 1 % max at 670 cm -1 (15 m m)

osbourne
Télécharger la présentation

FT-IR Instrument

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FT-IR Instrument

  2. Components • Source • Michelson Interferometer • Sample • Detector

  3. Sources • Black body radiators • Inert solids resistively heated to 1500-2200 K • Max radiation between 5000-5900 cm-1 (2-1.7 mm), falls off to about 1 % max at 670 cm-1 (15 mm) • Nernst Glower – cylinder made of rear earth elements • Globar- SiC rod • CO2 laser • Hg arc (Far IR), Tungsten filament (Near IR)

  4. Michaelson Interferometer • 1014 Hz is too fast for P to be directly measured as a function of time • Can not measure the FID signal directly • Interferometer creates a replicate interference pattern at a frequency that is a factor of 1010 times slower • 104-105 Hz can be measured electronically • f = (2vm/c)n = 10-10n, vm = 1.5 cm/s

  5. Michaelson Interferometer • Beam splitter • Stationary mirror • Moving mirror at constant velocity • Motor driven Micrometer screw • He/Ne laser; sampling interval, control mirror velocity

  6. Stationary mirror HeNe laser Beam Splitter Source Moving mirror PMT Sample Detector

  7. Sample • Sample holder must be transparent to IR- salts • Liquids • Salt Plates • Neat, 1 drop • Samples dissolved in volatile solvents- 0.1-10% • Solids • KBr pellets • Mulling (dispersions) • Quantitative analysis-sealed cell with NaCl/NaBr/KBr windows

  8. Detector • Transducers • The heating effect of radiation • Thermal transducer- black body, small, very low heat capacity- DT=10-3 K, housed in vacuum, signal is chopped • Thermocouples • Two junctions of dissimilar metals, An and Bi • One is IR detector, one is reference detector • Potential difference that develops in proportional to DT; detection of DTs of 10-6 K is possible

  9. FT-IR detectors • Pyroelectric tranducers

More Related