Time resolved transient transmission spectroscopy of TiCl₄ and SnCl₄

Herewith, for the first time, we present the vibrational spectra collected for liquid TiCl₄ and liquid SnCl₄ by use of time resolved transient transmission spectroscopy. Of our interest is the isotopically split isotropic ν₁ intramolecular vibrational band, the shape of which is very sensitive to intermolecular interactions. The high resolution spectra, obtained as fast Fourier transforms of the time domain signals acquired in transient transmission experiment, are compared with spontaneous Raman spectra. The dependence of the spectrum shape on intermolecular interactions has been established by diluting TiCl₄ and SnCl₄ in CS₂ at different concentrations. Fitting the simplified oscillatory model of a liquid to FFTs of time domain signals in transient transmission experiment we have found intermolecular force constants and decoherence lifetimes for all concentrations. Application of the pump-probe spectroscopic technique and windowed fast Fourier transform procedure allowed us to observe the evolution of the spectral shape, and thus of the intermolecular forces, after the liquid has been perturbed by the femtosecond pump pulse.