Crossed Molecular Beam Study The Reaction Of Fluorine Atoms And Trans 1,3-butadiene Molecule

Universal crossed molecular beam techniques based on electron impact ionization nave been essential in investigating the dynamics of bimolecular chemical reactions Recently, a new low background and high sensitivity crossed molecular beam apparatus with an improved universal detector has been constructed at Institute of Atomic and Molecular Sciences in Taipei by Xueming Yang etc. Much lower background in the detector ( <10-12 Torr ) has also been achieved using multiple ultrahigh vacuum pumps. The H2 background in the detector can be reduced by about two orders of magnitude in comparison with previously built similar instruments. Backgrounds at m/e= 1 ( H ), 28 ( CO+ ), 16 ( CH4+, O+ ), 15 ( CH3+ ), 14 ( CH2+ ) and 13 (CH+) in the ionization region are also significantly reduced.By this apparatus, crossed molecular beam studies of fluorine atom plus trans-1,3-butadiene reaction has firstly been carried out in detail. Different products angular distributions and velocity distributions were observed, indicating single H atom formation channel in this reaction. Data measured in the laboratory frame were converted to that in the center-of-mass frame to obtain product kinetic energy distributions and angular distributions in the center-of-mass frame. From the velocity-angle-flux diagram and almost isotropic angular populations of product kinetic energy in the center-of-mass coordinate, it indicates that the channeldominantly proceeds via a long-lived complex in collisional energy of 5.7 kcal/mol.