Hamid Reza Shemlouei - Department of Chemistry, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Iran
Elham Forootan - Department of Chemistry, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Iran
Mahmoud Tabrizchi - Department of Chemistry, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Iran

Thermodynamics and kinetics of Ion molecule reactions are studied with various techniques such as; high pressure mass spectrometry [1], selected ion flow drift tube[2], proton transfer mass spectrometry[3] and ion mobility spectrometry [4]. These techniques normally use a drift tube in where ion-molecule reactions take place or ions are separated and identified based on their mobility. The drift tube consists of a series of rings with equally potential between adjacent rings. Usually, ions are lost as they drift through the tube. In our previous work the transmission of different ions in a drift tube was studied[5]. The aim of this work is to explore the effect of length and diameter of the tube on its transmission for ions.