The focal electric fields for a 4π high numerical aperture (NA) focusing system with both the doughnut and higher-order Laguerre-Gaussian (LG) radially polarized (RP) beams are investigated in the case of NA=1, and the full width at half-maximum values of the focal spots are calculated. Compared with the single-lens high NA focusing configuration, a sharper spot, whose size is reduced efficiently in the transverse as well as the axial direction, can be formed. Such size reduction is attributed to not only the destruction interference of the longitudinal component caused by the π phase shift between any two adjacent rings of the incident higher-order LG RP beam coming from one particular direction but also the perfect destruction interference of the radial component formed by the two counter-propagating incident beams.

The first enantioselective synthesis of cytotoxic natural products rigidiusculamides A (ent-21) and B (8) has been achieved by two synthetic routes. The first one is convergent based on the common intermediate 11, obtained through a high yielding SmI(2) -mediated Reformatsky-type reaction. A highly diastereoselective one-pot Dess-Martin periodinane-mediated bis-oxidation allowed the direct conversion of the diastereomeric mixture of 11 into rigidiusculamide B (8). Isolation of minor diastereomer 21, in combination with computational work, allowed us to suggest the structure of the natural rigidiusculamide A to be ent-21, as synthesized by the second route. Four diastereomers (7, ent-7, 22a, and 22b) and an enantiomer (21) of rigidiusculamide A (ent-21) have been synthesized. On the basis of literature precedents and computational work, a biosynthetic pathway for rigidiusculamides A and B was proposed to account for the opposite configuration at C-5 of those two congeners.

The influence of 12 nm spherical silver nanoparticles (AgNPs) and 20 nm spherical gold nanoparticles (AuNPs) on the luminescence of europium complex Eu(TTFA)3 were studied. When 350 nm is chosen as the incident light, the maximum enhancement factor of the complexes mixed with AgNPs is about 2.5 at the wavelength of 612 nm. Besides the enhancement of the localized field, the overlap between the localized surface plasmon resonance spectra of nanoparticles and the absorption band of fluorescent molecules is another important factor for excitation field enhancement. By means of the quasi-static approximation theory, the distribution of the electric field around a single spherical metallic nanopaticle illuminated by plane wave was calculated. The simulation results show that the field enhancement effect is more obvious when the incident light is close to the resonance of the metallic nanoparticle, which could be demonstrated by our following experimental results. The distribution of the electric field under the same conditions was also simulated through the COMSOL software. The results are consistent with those of the quasi-static approximation theory.

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We investigate three-dimensional focus shaping generated from double-mode cylindrical vector beams with the Gaussian and Bessel-Gaussian pupil apodization functions by choosing the suitable polarization states of beams. Further, we compare them with that generated from the Laguerre-Gaussian pupil apodization function in the same situation. We find that the focus shaping generated from the Gaussian beam has the smallest zero intensity spot size. However, the situation of the Bessel-Gaussian beam not only possesses stability, which makes it suitable when applied in optical trapping, but also shows the best uniformity, which indicates its excellent performance in super-resolution fluorescence microscopy.