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Creado por rb.russell1
hace más de 9 años
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Infra-red Spectroscopy
Bonds vibrate in 2 different ways: stretching bending
Mass Spectrometry
We use wave numbers because frequencies in Hz are often VERY LARGE. If the TRANSMITTANCE is 100%, then no radiation is absorbed. You can identify the FUNCTIONAL GROUP by reading the wave number @ a peak.
wave number= no' of waves in 1 cm (units: cm^-1)
Used to: IDENTIFY unknown compounds determine the ABUNDANCE of isotopes in an element gain info. on the STRUCTURE of molecules detect POLLUTANTS and toxic chemicals detect drugs
How it works: Ionisation- molecules become +ve ions when electron is knocked off Acceleration- molecular ions speed up Deflection- ions deflected round a bend by magnetic field. Field strength required links directly to ion's mass Detection- ions detected and info. fed to computor
m/z= mass:charge ratio (charge always 1)
Molecular ion peak: furthest peak to the right of the graphm/z value= Molecular mass
Fragmentation: excess energy causes bonds to weaken molecules split into 1 +ve ion and one neutral species ions detected neutral species aren't Isomers have the same Mr but different fragmentation patterns
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