# Mollow Sidebands

We have shown that sidebands of the usual odd harmonics occur in high harmonic spectra of open shell molecules at equilibrium geometries. The sidebands are due to a driving laser induced one-photon coupling (Rabi flopping) between one of the inner valence orbitals and the HOMO, a mechanism analogous to Mollow triplets known from quantum optics. The phenomenon is found and illustrated for parallel as well as perpendicular transitions, di-, tri- and polyatomic molecules (see Figure).

Y. Xia and A. Jaron-Becker, *Opt. Express* **24**, 4689 (2016)

# Multielectron Contributions in HHG

High harmonic generation (HHG) is an important spectroscopic tool to study the response of molecules to intense laser fields. Usually, in these studies the single-active-electron approximation is applied, in which the dynamics of electrons from different orbitals are considered independently from each other. However, using time-dependent density functional theory we have shown that multielectron effects play an important role for the interpretation of recent experimental data for the ellipticity of higher-order harmonics from nitrogen molecules. In particular, our results contain essential contributions from the HOMO, the HOMO-1 and the HOMO-2 orbitals over the whole HHG spectrum (see Figure).

Y. Xia and A. Jaron-Becker, *Opt. Lett.* **39**, 1463 (2014)