5 And 6-Benzyluracil Lab Report

Abstract: The fully propagated real time-dependent density functional theory method have been applied to study the laser--molecule interaction in 5- and 6-benzyluracil (5BU and 6BU). Different parameters like direction, strength, wavelength of the laser field have been chosen in order to obtain the most efficient excitation of molecules. Results show that the 5BU and 6BU molecular systems have different responds to the applied laser field and different, well defined laser field parameters can be chosen in order to have highly efficient and selective excitation behavior for the studied molecular systems. On the other hand, it was demonstrated that the molecular excitation is a very complex conjunction of different one-electron orbital depopulation-population
In Fig. 7 we have compiled the total fractional electron depopulation of the first seven occupied orbitals for 5BU using the three laser intensities, while the field direction was set along the direction of {\emph Z} axis. The same results for 6BU are shown in Fig. 8. As it could be observed, the intensity value of 1.40$\cdot10^{11}$ W/cm$^2$ induce relatively small depopulation-population effects of the occupied-virtual orbitals for both 5BU and 6BU cases, while for the 8.76$\cdot10^{11}$ W/cm$^2$ intensity value we have obtained steadily increasing depopulation-population rate. During the 23 fs time-scale, if one applies laser field with higher intensity value (2.24$\cdot10^{12}$ W/cm$^2$) this increasing tendency remains quite similar for 6BU, but shows a saturation followed by a small decreasing for 5BU. In both molecular cases the peak intensity value of 2.24$\cdot10^{12}$ W/cm$^2$ induces almost a double amount of fractional electron excitation ($\approx$ 1.25{\emph e} for 5BU and $\approx$ 2.2{\emph e} for 6BU) than that of 8.76$\cdot10^{11}$ W/cm$^2$ ($\approx$ 0.7{\emph e} for 5BU and $\approx$ 1.2{\emph e} for 6BU). If one analyses the different occupied and virtual one-electron orbital behavior, as is presented in Fig.-s S11 and S12 of ESI$\dag$, a much more complex picture of
The results have shown that there are significant differences in case of the efficiency of the laser field absorption applied along the three principal axes of the molecules. 5BU can be easily excited if one applies the laser field along the {\emph Y} or {\emph Z} axes, while 6BU could efficiently absorbs it only if the field is applied towards the {\emph Z} axis. The absorption efficiency can be increased if the polarization of the laser field is not considered along the one of the principal axes, but through the combination of different vector directions. Accordingly, for 5BU we have obtained the highest excitation efficiency if the field is orientated along the {\emph YZ} direction, while 6BU gives the highest yield of absorption for the {\emph -YZ} direction, which is perpendicular on the previous direction. This fact clearly demonstrates the necessity of the molecular alignment before the molecular system is being excited by a laser