Uzaysal ve zamansal olarak modifiye edilmiş lazer alanları ile moleküllerin yönlü ayrışması

In this thesis, the results of the four fundamental subjects of ultra-fast physics andthe theoretical foundations of these results are explained. In addressing these issues, laser pulse has been modified in various ways, both spatially and temporally. In the intensity dependence of dissociation, it has been shown in a simple way which dissociation channel is opened at which intensity. In these calculations, the system was moved around a nanotip and the effect of this nanotip on the dissociation channels was also examined. In the second part, a post-pulse is added to the two-cycle, ultra-short laser pulse with gaussian-envelope. The motivation here is that it is very difficult to create a clean laser pulse in real experimental settings. Because of this difficulty, a relatively weak post-pulse is added and the effect of this pulse on the results was examined theoretically. This post-pulse has been observed to affect the BS and especially the ZPD channels due to the long time scales and modifies the dissociation and asymmetry inthe low KER region where these two channels overlap. In the case of chirped ultra-short laser pulses, the form of chirping, called "Pulse-Width Maintained Chirping", is theoretically proposed. This shows that for positivechirp, the ATD channel shifts towards low energies. With detailed investigation of the isotope effect, important results were obtained regarding the dissociation yield and asymmetry. In this part, the system has been moved around a metallic nanotip. In this way, the laser interacted with both the molecule and the nanotip, and the system was dissociated by a space-dependent electric field by creating a space-dependent near field around the nanotip. Both heteronucleus and homonucleus isotopes of the hydrogen molecule have been studied. It has been observed that the dissociation yield decreases with the increase in mass, but the dissociation peaks shift towards higher energies, with a linear dependence on the mass number. In the thesis, the asymmetry contrast formed as a result of the space-dependent near field is also examined in detail.