Berlin 2001 – wissenschaftliches Programm

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AMPD: EPS AMPD

AMPD 5: Sitzung 5

AMPD 5.6: Vortrag

Mittwoch, 4. April 2001, 11:45–12:10, H105

Velocity map imaging following laser induced photodissociation of molecules — •David H. Parker — Laser and Molecular Physics Dept., University of Nijmegen, The Netherlands

Velocity mapping [1,2] is an improvement of the ion imaging technique [3] introduced by Chandler and Houston in 1987. In velocity mapping an electrostatic immersion lens is used which has the wonderful property of mapping each different product velocity to the same point on the imaging detector, independent of the initial position of the particle. Furthermore, this is possible without the use of fine–wire grids that tend to block and distort the ion trajectories. This advance led to a very substantial improvement in the velocity resolution of ion imaging and to new progress in several fields of molecular dynamics research including crossed-beam reactive scattering [4]. In this talk the velocity mapping technique is described and applications are illustrated in studies of the photodissociation / ionization dynamics of molecular oxygen. Emphasis will be given to the utility of the product angular distributions for the deconvolution of overlapped continua in direct dissociation and the analysis of rotational effects in predissociation. The advantages of velocity map imaging of photoelectrons is also illustrated in analysis of resonance enhanced multiphoton ionization (REMPI) processes in O₂.

[1] Eppink, A. T. J. B., Parker, D. H. Rev. Sci. Instr. 1997, 68, 3477.

[2] D. H. Parker, In Photoionization and Photodetachment, Advanced Series in Physical Chemistry, Vol 10A and 10B, Ng, C., Ed., World Scientific Publishing Co. Ltd. Singapore, 2000; D.H. Parker, Molecular Oxygen Photochemistry, Accounts of Chemical Research, 33 (2000).

[3] Chandler, D. W., Houston, P. L. J. Chem. Phys. 1987, 87, 1445; Heck, A. J. R., Chandler, D. W., Annu. Rev. Phys. Chem. 1995, 46, 335.

[4] R. F. Delmdahl, B. L. G. Bakker, and D. H. Parker J. Chem. Phys. 113 (2000) 7728–30.