Time resolved laser studies of gas phase and condensed phase molecules

Sammanfattning: Different laser based techniques have been used to study lifetimes and spectra of gas phase molecules, and non-linear optical phenomena in condensed phase materials.The lifetimes of several electronically excited states of the diatomic molecules vanadium oxide, VO, zirconium sulphide, ZrS, titanium sulphide, TiS and titanium oxide, TiO have been performed by resonant two-photon ionisation spectroscopy in a molecular beam combined with a time of flight mass spectrometer. The identities of some previously unknown electronically excited states in some of the molecules are proposed. The lifetimes of electronically excited states of BaCl have been determined using the delayed coincidence technique.Femtosecond pump-supercontinuum-probe transient absorption spectroscopy was employed to study non-linear optical phenomena in UV fused silica, ethylene glycol, BK7-and BS7-optical glasses. Signals related to both the third (χ(3)) and the fifth (χ(5)) order non-linear susceptibilities were observed. The experimental results were compared with numerical simulations, and absolute values of the real and imaginary parts of the fifth order non-linear susceptibility of UV fused silica were determined.