Circularly polarized attosecond light generation from OCS molecules irradiated by the combination of linear polarized infrared and orthogonal terahertz fields.

Researching ultrafast dynamics and creating coherent light sources will both benefit significantly from the establishment of polarization control in high-order harmonic generation (HHG). By employing the time-dependent density functional theory method, we investigate HHG of carbonyl sulfide molecules using a combination of a linear polarized infrared (IR) laser and a weaker orthogonal Terahertz (THz) field. Our findings show that by adjusting the amplitude of the THz field, the movement scale of electrons in the THz direction can be tuned, thereby one can control the harmonic intensity in the IR laser direction.

Minimum structure of high-order harmonic spectrum from molecular multi-orbital effects involving inner-shell orbitals.

The spectral features of high-order harmonic spectra can provide rich information for probing the structure and dynamics of molecules in intense laser fields. We theoretically study the high harmonic spectrum with the laser polarization direction perpendicular to the NO molecule and find a minimum structure in the plateau region of the harmonic spectrum. Through analyzing the time-dependent survival probability of different electronic orbitals and the time-dependent wave packet evolution, it is found that this minimum position is caused by the harmonic interference of HOMO a, HOMO-1, and HOMO-3 a orbitals.

Significantly enhanced conversion efficiency of high-order harmonic generation by introducing chirped laser pulses into scheme of spatially inhomogeneous field.

An effective scheme to enhance the yield of high-order harmonic generation originated from spatially inhomogeneous field through the interaction between few-cycle chirped laser pulses and a nano-tip structure is demonstrated. The conversion efficiency of harmonics from chirped laser pulses was significantly improved by nearly three more orders of magnitude than that of chirp-free pulses, and the cutoff energy of the corresponding harmonics was dramatically enhanced. By superimposing a series of properly selected orders of harmonics, isolated attosecond pulses of high intensity can be obtained.

Chirp-free isolated attosecond pulse generation from an atom irradiated by a fundamental terahertz pulse synchronizing an infrared laser pulse.

We theoretically study high-order harmonic generation (HHG) and attosecond pulses from an atom irradiated synchronically by a terahertz (THz) pulse and an infrared laser pulse. For the HHG spectrum from the THz pulse alone and the combined pulse, an apparent peak-valley structure appears the platform region. Specially, for the periodic structure generated by an atom under the action of the combined pulse is originated from the interference between the electrons ionized at different instants in the laser field, which undergo many recollision and return to the core at the same time.

Structure-activity relationship studies of 3-aroylindoles as potent antimitotic agents.

The concise synthesis and structure-activity relationship (SAR) studies of 3-aroylindoles were carried out in an effort to improve the potency and solubility of anticancer drug candidate BPR0L075 (8) by exploring structure modifications through three regimens: substitution of the B ring, at the N1 position, and of the 3-carbonyl linker. The SAR information revealed that the methoxy group of the B ring could be replaced with an electron-donating group such as methyl (in compound 9) or N,N-dimethylamino (in compound 13) while retaining both strong cytotoxic and antitubulin activities. The introduction of amide (compounds 30-33) and carbamate (compounds 34-37) functionalities at the N1 position of 8 gave analogues with potent antiproliferative activities.