Hannover 2020 – scientific programme

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MO: Fachverband Molekülphysik

MO 10: Collisions and Reactions

MO 10.7: Talk

Wednesday, March 11, 2020, 12:30–12:45, f142

Velocity map imaging of chlorine from photodissociation with a [1+1]-REMPI scheme — •Christian Matthaei, Deb Pratim Mukhopadhyay, and Ingo Fischer — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Velocity map imaging (VMI) is a well-established method for studying the photodissociation dynamics of molecules [1]. When studying chlorine fragments, a [2+1] resonance-enhanced multiphoton ionization (REMPI) scheme is usually employed, requiring a laser with a wavelength of around 235 nm. Since many molecules and radicals also absorb light of this wavelength, the dissociation is generally performed with the same laser. The major disadvantages of these one-colour experiments are that a clean study of the molecules of interest is not always feasible and the dissociation wavelength cannot be changed.

Here, we present a technique for first dissociating molecules with one dye laser and then ionizing chlorine with a second dye laser via a novel [1+1]-REMPI scheme. For the ionization the output of a dye-laser is tripled in a noble gas-filled cell, generating 118 nm light in order to directly promote the electron into the excited state. Following ionization, the chlorine atoms are then detected via time-of-flight mass spectrometry and VMI. First measurements on test systems are shown.

Literature:

[1] M. N. R. Ashfold et al., Phys. Chem. Chem. Phys. 2006, 8, 26-53