This paper proposes highly charged ions pumped by intense laser to produce very high order harmonics. Numerical simulations and full quantum theory of Ne 9+ ions driven by laser pulses at 1064 nm in the power range of 10 9 W/cm 2 ∼ 10 15 W/cm 2 show that the emission spectrum corresponds to the electronic transitions from the excited states to the ground state, which is very different from the spectrum of general high-order harmonic generation. In such situation, harmonic order as high as 1000 can be obtained without producing lower order harmonics and the energy conversion efficiency is close to general high order harmonic generation of hydrogen atom in the same laser field.

For a long time, empirical formulars have been used to predict the steady-state creep rate due to lack of clear microscopic description of the mechanism, which frequently leads to unreliable predictions. In this work, a statistical model of single atom developed recently is used to predict the steady-state creep rate at an atomic diffusion level. To test the model, we measure the creep rates of three kinds of materials, i.e., 42CrMoA, 2Cr12Ni, and 1Cr12Mo, and collect the experimental data of other materials, such as IN738LC and K435. The results show that our theoretical predicts are in good agreement with the experimental results.

The critical criterion for realizing population trapping is deduced for a two-level system driven by a frequency-modulated laser field in terms of dressed atom model, followed by demonstrating the various population trapping behaviours under different conditions. Detailed numerical solutions of time-dependent Schr?idinger equation are found to be in good agreement with the analytical results.

We report the first experimental investigation of the photoionization cross-sec-tions of singlet excited ststes 3858's and 3s4d'D in atomic magnesium, which can not be directly reached from the ground state. The measured absohte values are us.5.1S (571.lnm)=(0.27fO.O9)Mb and (TJs#D (552.8nm)=(2.6fO.9)Mb. Theoretical calculations were given, which are in good agreement with the measured values.