Collision induced dissociation (CID)

TOF-CID spectrum of mass selected  Ti3O5 + and fragments

 

BACK

A particular ion (parent) is selected from the clusters’ size distribution using a mass-gate. Some energy is transferred to the cluster through collisions with Kr atoms in a collision chamber, leading to its fragmentation. Because of energy conservation, the fragments have lower kinetic energy than the parents and penetrate less deep into the reflectron and arrive earlier at the detector. Thus, they are separated from the parent masses in the TOF spectrum. The fragmentation cross-section which in this case is the lower limit of the integral collision cross-section is obtained.

Installation of a beam-gas cell collision chamber for CID experiments in the 0.1 to 1 keV energy range. By measuring the integral collision cross-section and calculation of the geometrical cross section,  information about the structure of transition metal oxide clusters is obtained for the systems  VxOy + Kr, NbxOy + Kr and TixOy+ + Kr.

Example TixOy+ + Kr.

 The fragmentation cross-section which in this case is the lower bound of the integral collision cross-section is obtained by normalizing the total intensity of ions  by the intensity of the parent :           

The experimental cross-sections (points) are normalized to the theoretical ones (lines), which are estimated with the geometric projection model using minimum energy structures of TixOy+ clusters calculated from different theoretical groups

References:

Michalis Velegrakis, Maria Massaouti,  Maria Jadraque, “Collision-induced dissociation studies on gas-phase titanium oxide cluster cations “Applied Physics A 107  (2012) DOI 10.1007/s00339-012-6854-1

Comparison of integral collision cross section (CID) with ab-initio calculations

Experiment

ó

Theory

ó

STRUCTURE CHARACTERIZATION WITH GEOMETRIC PROJECTION MODEL