ArF excimer laser photolysis of tetramethyltin Sn(CH3)4 probed by dye-laser-induced resonant multi-photon-ionization

Laser-photolysis of tetramethyltin Sn(CH3)4 (TMT) is very interesting being this molecule an attractive precursor for laser photodeposition of Sn thin films. Efficient dissociation and ionization are obtained irradiating the organometallic with the ArF laser beam, being the energy of one photon at 193 nm resonant with the first TMT absorption band. At low laser radiation density, the observation of the Sn(CH3)3 + ion dominating the mass spectrum shows that photolysis is initiated by the elimination of one methyl group. The relative abundance of lighter SnCH3 + and Sn+ ions is strongly depending on the energy density. Neutral photoproducts of the UV photolysis are sampled by dye-laser-induced resonant Multi-Photon Ionization (MPI); suitable wavelengths are idenfified through visible MPI in the 370-410 nm range. Futhermore neutral CH3 fragments are detected by 2R+1 ionization induced at 333.5 nm. Varying the delay between the UV and the probing laser pulses, informations on the reaction dynamics are achieved. The presence of a strong dissociative channel evidence by the two-color ionization experiments demonstrates the suitability of TMT as metal precursor for ArF laser induced deposition of Sn and Sn-containing films.