Spectrophotometry
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What is the principle of spectrophotometry? (Lecture’s principle) (2)
Spectroscopy makes use of the fact that different substances absorb or emit electromagnetic radiation in different ways These differences are observed in the spectra of substances by using a spectrophotometer
What is a spectrometer?
Its a photometer (a device for measuring light intensity) that can measure intensity as a function of the colour, or more specifically, the wavelength of light
What is a spectroscopy?
Spectroscopy is a type of chemical analysis done by shining light on a sample to determine what is inside
How do biochemists make use of spectrometry?
Biochemists measure the absorbance or transmittance of a sample
What is absorbance?
How much light is absorbed by the sample
What is transmittance?
How much light passes through the sample
List the parts of the spectrophotometer. 4
A light source A holder for the sample A diffraction grating or monochromator to separate the different wavelengths of light A detector
What is a monochromator/diffraction grating?
An optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input.
What is absorbance?
A quantitative measure of the extent to which a compound absorbs ultraviolet-visible radiation at a particular wavelength
What is transmittance?
A quantitative measure of the extent to which a compound absorbs ultraviolet-visible radiation at particular wavelength
What does Beer Lambert’s Law tell us?
Beer’s Law tells us that if a solute absorbs light of a particular wavelength, the absorbance is directly proportional to the concentration of substance in solution.