spectroscopy 2 Flashcards
what are the two types of atomic spectroscopy?
1- atomic emission
2- atomic absorption
if your energy is in the form of a radio wave what spectroscopy do you have?
atomic absorption spectra
if your energy is in the form of a flame what type of spectroscopy do you have?
flame emission spectra
what group in the periodic table is emission best for?
group 1- mostly bodily fluids eg lithium
what group is absorption better for?
higher group elements
what does the intensity of the light depend on?
number of atoms in the excited state
what kind of light is emitted from the flame?
propane think bandwith
what are the two limitations associated with the spectra?
1- self absorption- has to be linear and at higher conc. iit is not linear
2-excitation source- flame is not a homogeneous temp
what is the hollow cathode lamp?
glass tube filled with inert gas with the element to be analysed
positive ions are accelaterated towards the cathode
metal atoms are in gas phase
what is absorption defined as?
A = -log T = -log I/I0= a x b x c
what law does absorption follow?
beer lambert law ( linear)
what are limitations of the hollow cathode lamp?
- must have a large volume
- sensitive detection
- not possible to analyse solid samples
what are the 3 types of interferences in AA?
chemical
ionisation
spectracal
how does chemical interfere with AA?
molecule must be thermo stable complex with ionically stable species
if not releasing agent must be added
how does ionisation affect AA?
Alkali and alkaline earth metals have low ionization potential
so addition of ionisation suppressor ( something that ionises easier)
