High harmonic generation in H$_{2}^{+}$ and HD+ by intense femtosecond laser pulses: A wave packet approach with nonadiabatic interaction in HD+

Pramana

Farzana Sharmin¹  Samir Saha¹  S S Bhattacharyya¹ 

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关键词: High harmonic generation;    H$_{2}^{+}$;    HD+;    wave packet;    nonadiabatic interaction.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

We have theoretically investigated the high harmonic generation (HHG) spectra of H$_{2}^{+}$ and HD+ using a time-dependent wave packet approach for the nuclear motion with pulsed lasers of peak intensities (𝐼0) of 3.5 × 1014 and 4.5 × 1014 W/cm2, wavelengths (𝜆L) of 800 and 1064 nm, and pulse durations (𝑇) of 40 and 50 fs, for initial vibrational levels 𝜈0 = 0 and 1. We have argued that for these conditions the harmonic generation due to the transitions in the electronic continuum by tunnelling or multiphoton ionization will not be important. Thus, the characteristic features of HHG spectra in our model arise only due to the nuclear motions on the two lowest field-coupled electronic states between which both interelectronic and intraelectronic (due to intrinsic dipole moments, for HD+) radiative transitions can take place. For HD+, the effect of nonadiabatic (NA) interaction between the two lowest Born–Oppenheimer (BO) electronic states has been taken into account and comparison has been made with the HHG spectra of HD+ obtained in the BO approximation. Even harmonics and a second plateau in the HHG spectra of HD+ with the NA interaction and hyper-Raman lines in the spectra of both H$_{2}^{+}$ and HD+ for 𝜈0 = 1 have been observed for higher value of 𝐼0 or 𝜆L. Our calculations indicate reasonable efficiencies of harmonic generation even without involving the electronic continuum.

【 授权许可】

Unknown