Positive/negative ion velocity mapping apparatus for electron-molecule reactions.
In molecular dissociative ionization by electron collisions and dissociative electron attachment to molecule, the respective positively and negatively charged fragments are the important products. A compact ion velocity mapping apparatus is developed for the angular distribution measurements of the positive or negative fragments produced in the electron-molecule reactions. This apparatus consists of a pulsed electron gun, a set of ion velocity mapping optic lenses, a two-dimensional position detector including two pieces of micro-channel plates, and a phosphor screen, and a charge-coupled-device camera for data acquisition. The positive and negative ion detections can be simply realized by changing the voltage polarity of ion optics and detector. Velocity sliced images can be directly recorded using a narrow voltage pulse applied on the rear micro-channel plate. The efficient performance of this system is evaluated by measuring the angular distribution of O(-) from the electron attachments to NO at 7.3 and 8.3 eV and O(+) from the electron collision with CO at 40.0 eV.
Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China.
Bin
B
Wu
Lei
L
Xia
Hong-Kai
HK
Li
Xian-Jin
XJ
Zeng
Shan Xi
SX
Tian