7627

7099

كارشناسي ارشد

شيمي فيزيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده شيمي

1391

يازده،84ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

حسين فرخ پور، محمود تبريزچي

حسن قاضي عسگر

20/1/92

مهدي رنجبر، محمد ژياني

شيمي

ID7099

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Mass Spectra of Alkaline Earth Chlorides by Laser Ionization Time of Flight Mass Spectrometry Maryam Alsadat Mirian mmirian66@yahoo com Jan 1 2013 Department of chemistry Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi H Farrokhpour h farrokh@cc iut ac ir M Tabrizchi m tabriz@cc iut ac ir Abstract Time of flight TOF mass spectrometry MS is one of the most sensitive and widely used methods for material analysis In TOF MS molecules are ionized accelerated and separated in a field free region In fact ions of different m z are dispersed in time during their flight along a field free drift path of known length The lighter ones will arrive earlier at the detector than the heavier ones Compared to other mass analyzers including magnetic sectors quadrupole and ion traps TOF can readily reach mass resolving power of 10000 or more with very high efficiency Since in TOF mass spectrometry a complete mass spectrum is generated in only microseconds the instantaneous data acquisition allows signal averaging to increase the signal to noise ratio in short analysis times In this work mass spectra of earth alkaline halides have been studied using laser ionization technique and a homemade time of flight mass spectrometer constructed in Isfahan University of Technology The spectrometer is a linear TOF and was operated in positive ion detection mode Solid samples were coated on a plate acted as the repeller in the accelerator The plate was then irradiate with an Nd YAG laser light at third harmonic 355nm The vacuum of the TOF mass spectrometer was kept at 10 7 mbar during the experiments Background mass spectrum of stainless steel plate and aluminum foil as supporting plate were recorded Aluminum foil was better since a fresh one can be used for each substance and its background mass spectrum was more privacy than that of stainless steel Time of flight spectra of MgCl2 CaCl2 SrCl2 and BaCl2 were recorded and assigned To assign the peaks approximate masses were first calculated using the calibration curve was then obtained by plotting the square root of standard masses versus flight times In mass spectra of CaCl 2 SrCl2 and BaCl2 ions of M MCl and MCl MCl2 with different isotopes were identified where M is alkali earth atom To support the assignments the isotope patterns of the M and MCl peaks were simulated A Gaussian shape function was considered for each peak The intensity for each peak was taken as the product of natural abundances of

حسين فرخ پور، محمود تبريزچي

حسن قاضي عسگر

مهدي رنجبر، محمد ژياني