Atomic Absorption Spectroscopy Flashcards
what is the function of AAS
to measure how much and the concentration of an element present in a substance
what are the 4 components of a spectrometer in order
hollow cathode lamp, vaporiser, mono-chromator and detector
explain step 1 the cathode lamp
made up of the same metal to be tested for, it emits gas that feeds the flame
explain step 2 the vaporiser
the light produce passes through a sample in vaporised form/atoms. only the elements being tested for will absorb the light
in relation to step 2 why does the light only get absorbed by the element being tested
electrons cant absorb energies of the foreign elemental light because energy levels are different
explain step 3 the mono chromator
mono chromator or light prism narrows down light waves and picks only ONE wavelength of light for analysis
explain step 4 the detector
measures the intensity of light displayed as a number showing the amount of light that hasnt been absorbed
what is the callibration curve used for
to measure the amout of element present, the absorbance of light of that element is compared to that of known samples
how do you construct a callbiration curve 2 steps
- number of known element concentrations are prepared and intensities measured by AAS
- concentration of another sample to be compared and determined its absorbance is measured shown by plotting curve - concentration against absorbance
What is the emission spectrum
wavelengths of light emitted by an excited atom are unique for that atom because of unique energy amounts
when excited atoms jump levels, that return to ground state and emit energy if the form of light
(electrons go from high to low energy level used for FLAME TEST)
what is the absorption spectrum
atoms will absorb light at wavelengths unique to their emission spectrum
(electrons go from low to high energy levels AAS)
