Extreme ultraviolet photon effect on ionization and recombination of high-order harmonic generation Hang Liu, Liqiang Feng, Yan Qiao and Xiaodan Jing Eur. Phys. J. D, 75 4 (2021) 144 Published online: 29 April 2021 DOI: 10.1140/epjd/s10053-021-00153-0