field desorption

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1. BYABDUL QQAAYYOOOOMM MMUUGGHHEERRIIMMpphhiill sscchhoollaarr2 2. IntroductionExperimental techniquesIonization sourcesMechanismComparison FD and FIAdvantagesApplicationsConclusionAcknowledgment3 3. Field desorption has beenconsidered as offspring offield ionization and thus theprinciples governing the ionformation have traditionallybeen treated in more or lesssimilar way.4 4. DesorptionRemoval of a substance froma surface on which it isadsorbed 5. FD was developed by H.D.Beckey in1969.A term used to describe the formation ofions in the gas phase from a materialdeposited on a solid surface (known asan 'emitter') in the presence of a highelectrical field.6 6. The development of the experimental techniquesof field desorption- MS Various types of emitterdifferent sample loading techniques are also. Automatic FD emitter heating devices and laserassisted.7 7. Field Desorption analyses featurethe following:Suitable for high molecular mass and/or thermallylabile substances such as polymers, peptides,carbohydrates and organic or inorganic salts.A solution of the sample is applied to the emitterbefore it is introduced into the ion source.The emitter is mounted on the tip of the axialsample introduction probe. 8. Field Ionization gas is passed overionization sourceField Desorption dipped in solutioncontaining sample and placed back inspectrometer9 9. Field ionization (FI) is a method thatuses very strong electric fields toproduce ions from gas-phase molecules.+++ ++++++++++d

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