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Coherence and Ultrashort Pulse Laser Emission Part 14

Tham khảo tài liệu 'coherence and ultrashort pulse laser emission part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 512 Coherence and Ultrashort Pulse Laser Emission Fig. 4c. Color online TDDFT LB94 orbital population Ni a t of CS2 for selective fixed angle 0 between the molecular axis and the laser polarization direction and I 1.72x1014 W cm2. Only the relevant KS orbitals which possess an important response to the laser field are shown with their label. CS2 LB94 1.7 x1014 w cm2 0 0 10 20 30 40 0 10 20 30 40 Harmonic Order N Fig.4d. Color online TDDFT LB94 harmonic spectra of CO2 for some angles between the molecular axis and the laser polarization direction. Laser pulse duration eight optical cycles peak intensity I 1.72 1014 W cm2 and wavelength 800nm. harmonic while when 0 90o the harmonic spectrum signal is significantly higher as expected resulting from a constructive interference as found in the CO2 and the H2 case.48 c. OCS Considering the nonsymmetric OCS case one finds that the amount of ionization computed using Eq.9 is nearly the same at the end of the eight cycle laser pulse around 7 independent of the laser molecule angle 0. However the difference between theses orientations on the harmonic spectra Fig.4e is remarkable. 513 Non Perturbative Time-Dependent Density Functional Theory TDDFT Study of Ionization and Harmonic Generation in Linear Di- N2 and Tri- CO2 OCS CS2 . For the parallel orientation 0 0 the spectra shows in the plateau region a striking pronounced minimum or destructive interference as for the CS2 and CO2 case around N 39. For 0 90o unlike what we find for the case of CS2 a minimum is found around N 25. This interference minimum is rather broad and as deep as is found for 0 0o. Although the oxygen and the sulfur atom experience exactly the same external electric field the minimum observed is due to the electronegativity and the IP difference between the two atoms. To explain these results we invoke the semiclassical picture of MHOHG. When the driving laser field is polarized perpendicular to the molecular axis if the two nuclei are identical CS2 and