طيف سنج تحرك يوني با منبع يونش فرابنفش

چكيده انگليسي :

160 Hamed Bahrami Hamed bahrami12@gmail com 24 February 2013 Department of Chemistry Isfahan University of Technology 84156 83111 Isfahan Iran Supervisor Dr M Tabrizchi m tabriz@cc iut ac ir Advisor Dr H Farrokhpour Department Graduate Program Coordinator Dr H Tavakol Department of chemistry Isfahan University of Technology 84156 83111 Isfahan Iran fax 983113912350 Abstract In the first part of this thesis a different design for the use of a photoionization source UV Lamp in Ion Mobility spectrometry IMS has been proposed Ion mobility spectra of several chemical compounds were obtained while the effect of dopant and solvent on the spectra were studied In this design a curtain electrode was mounted in front of the UV lamp to divide the ionization zone into two distinct regions Dopant was directly photoionized in the first region and then solvent molecules were ionized via proton transfer with the dopant photoions in the second region Finally the analyte were ionized by protonated solvent molecules This design consumes much less dopant than the conventional sources and leads to increased photoionization yield The second part of the thesis deals with employing two ion sources namely photoionization UV and corona discharge CD source in an ion mobility spectrometer The design is capable of using each source individually or the two sources simultaneously Ion mobility spectra of some chemical compounds obtained by each ionization sources were reported The limits of detection for acridine were obtained to be 0 11 and 0 30 ng for CD and UV respectively Finally simultaneous operation of the two ionization sources was investigated by recording ion mobility spectra of selected samples In the third part of the thesis attempts were made to assign the peaks in ion mobility spectra of some compounds with different protonation sites such as caffeine obtained by the two ionization sources Experimental and theoretical evidences were collected to link the observed peaks to related ionic species In the experimental part the effects of sample concentration as well as the nature of the reactant ions in the existence and intensity of each peak were evaluated In the theoretical part some parameters such as thermodynamic stability proton affinity dipole moment charge distribution electron density and chemical bond length as well as volume and surface area of protonated isomers of sample molecules were calculated Using the collected data and evidences some predictions about the origin of each peak were proposed Furthermore the new concept of internal proton affinity IPA was introduced which expresses the tendency of holding an added proton for different sites in a molecule Keywords ion mobility spectrometry ionization source Ultraviolet lamp corona discharge proton affinity caffeine 1 Introduction Ion mobility spectrometry IMS is an analytical technique for detection of different chemical compounds In IMS sample vapors are converted into ions at atmospheric pressure Ions are then identified by measuring their mobility in an electric field whichPDF created with pdfFactory trial version www pdffactory com

بهرامي، حامد

طيف سنج تحرك يوني با منبع يونش فرابنفش

لامپ فرانبفش , تخليه كرونا , پروتون خواهي , كافئين