Routes of odd-even harmonic emission from oriented polar molecules

Abstract

We study odd-even high-harmonic generation (HHG) from oriented asymmetric molecules with different symmetries in strong laser fields. A model based on strong-field approximations is used which allows us to resolve the contributions of different emission routes to odd-even HHG. The comparison between the HHG yields of all routes versus one certain route demonstrates that the routes in which the electron ionizes from the gerade component of the asymmetric orbital contribute mainly to odd-even HHG. We show that the potential mechanism is associated with effects of intramolecular interference in tunneling ionization as the bound electron passes through the barrier formed by the laser field and the asymmetric Coulomb potential. The influences of different emission routes on asymmetric orbital imagining with odd-even HHG are also addressed.

Effect of Molecular Charge Asymmetry on Even-to-odd Ratio of High-order Harmonic Generation

“…Specifically, with increasing the ratio Z 1 /Z 2 , the ratio F sharply increases, then approaches or exceeds one, before dropping dramatically. It is noticed that for harmonics near the cutoff, the ratio F undergoes a sharp maximum due to the destructive interference effect and this occurs for odd harmonics and is absent in even ones [23,26]. However, these sharp maximums are not seen in Fig.…”

“…6, we plot the ratio F as a function of X. It is shown that, after a sudden growth, the ratio F slowly changes with increasing of X value, except for a sharp maximum due to the destructive interference of odd HHG spectra [23,26]. For harmonics in the plateaus of HHG spectra, and R values as indicated in Fig.…”

“…The HHG spectra of those molecules possess both odd and even harmonics due to the symmetry breaking of the lasermolecule systems [14,17,19,22]. The odd-even HHG spectra can be applied for reconstructing the asymmetric molecular orbital [18], probing electron dynamics [17,[23][24][25][26], nuclear dynamics [27], and orientation degree of asymmetric molecules [28,29]. Notably, in 2017, Hu et al have first found the pure-even HHG spectra, i.e., the spectra contain only even harmonics when the laser electric field is perpendicular to the molecular axis of CO [19].…”

Alignment dependence of photoelectron momentum distributions for diatomic molecules N$_2$ in strong elliptical laser fields

“…For aligned symmetric diatomic molecules [31] with a not very large internuclear distance R, it has been shown that the interference of the electronic wave between these two atomic centers of the molecule under the barrier induces the remarkable increase of ionization yields of the target molecule in comparison with its partner atom with a similar ionization potential I p [32][33][34]. Further theoretical studies showed that this effect has important influences on alignment dependence of ATI [35,36], HHG [37] and NSDI [38] of symmetric molecules, as well as ATI and HHG of oriented asymmetric molecules [39].…”

Chụp Ảnh Cắt Lớp Phân Tử N2 Định Phương Không Hoàn Toàn Từ Phổ Sóng Điều Hòa Bậc Cao

“…Sau đó, phương pháp chụp ảnh cắt lớp đã được ứng dụng khi HHG phát xạ khi tương tác với laser hai màu (Zhai et al, 2018). Gần đây, phương pháp chụp ảnh cắt lớp đã được mở rộng cho phân tử bất đối xứng CO (Qin, Zhu, Zhang, & Lu, 2012;Chen, Fu, & Liu, 2013;Xie, Yu, Li, Wang, & Chen, 2018;Zhai et al, 2018;Yuan et al, 2018).…”