Gas phase synthesis of transition metal oxides

TOF-Mass Spectrum of TixOy+ Clusters

3 groups of stable TixOy+ clusters:

              (TiO2)n+

              (TiO)+(TiO2)n

              (TiO)+(TiO2)nO2

 

Photofragmentation spectra (@ 308 nm) —> explain the growth of the clusters from TiO+ and Ti2O3+ by sequential uptake of TiO2 building blocks

Titanium oxide clusters - Photodissociation

Non-resonant photofragmentation is not very efficient

Photons are replaced with atoms => lead to fragmentation through collision

References:

 

M. Velegrakis et al  Applied Physics A 97 (2009) 765

 

Maria Jadraque, Borja Sierra, Antonis Sfounis, and Michalis Velegrakis, “Photofragmentation of mass-selected titanium oxide cluster cations”, Applied Physics B,   100  (2010)  587

 

 

· Important species with potential applications in the fields of:

           - Physics (magnetism, nanoelectronics, ...)

           - Chemistry (catalysis, ...)

           - Biology (antibacterial properties, ...)

· Their properties strongly depend on the local environment of the metal atoms such as the coordination number and the oxidation number.

· These change as the cluster size increases.

Transition metal oxide clusters-Examples

 

Ta: [Xe]5d36s2 ; Ta+: 5d36s1

Oxidation numbers

Ta:+5,+4,+3,+2,+1

Ta+:+4,+3,+2,+1

 

Oxidation number

Oxygen:     - 2

Metal:    + ó

 

 

Main Series:

[Ta+4O-22]+ · [Ta+52O-25]n ,   

[Ta+42O-24] +· [Ta+52O-25]n

 

Zr:[Kr] 4d25s2

Oxidation numbers

Zr: +4,+3,+2,+1

Zr+: +3,+2,+1

 

Main Series:

[Zr+2O-2]+ · [Zr+4O-22]n

 

 

Stability Rule:

Neutral cluster   :  x · ó  =  y· 2

Cation(+1) :     x · ó  - 1 =  y· 2

Anion  (-1)    :     x · ó  + 1 =  y· 2