TY  - GEN
ID  - heidok7585
Y1  - 2007///
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/7585/
N2  - Reaction microscopes enable kinematically complete measurements of atomic and molecular fragmentation. An ultracold atomic target is usually provided by a supersonic gas jet. The apparatus developed in the course of this thesis for the first time combines the principle of the reaction microscope with a magneto-optical trap. This allows for the preparation of lithium atoms in the sub-mK range. Being a three-electron system, its simple atomic structure makes lithium a model system of great topical interest for all kinds of ionization reactions. In order not to deteriorate the determination of the momenta of the charged fragments by the magnetic field of the trap, a pulsed mode of operation is adopted, creating field-free conditions during data acquisition and making efficient use of the stored target. The novel apparatus provides a versatile target for investigations on fragmentation of lithium by electron, ion and photon impact. For the first time, momentum-resolved measurements on multiphoton ionization in intense laser fields with pulse durations of 25~fs and peak intensities in the range between 10$^{11}$~W/cm$^2$ and 10$^{16}$~W/cm$^2$ were performed. The acquired photoelectron spectra exhibit unexpected structures such as a preferred emission in the direction perpendicular to the laser polarization axis, which are not fully understood yet. Presently, corresponding calculations are being done in several theory groups.
TI  - Multiphoton Ionization of Laser Cooled Lithium
A1  - Steinmann, Jochen
KW  - Reaktionsmikroskop 
KW  -  MOT 
KW  -  Lithium 
KW  -  Multiphoton-Ionisation 
KW  -  COLTRIMSReaction microscope 
KW  -  MOT 
KW  -  Lithium 
KW  -  Multiphoton ionization 
KW  -  Recoil ion momentum
AV  - public
ER  -