Two novel polarization transformers, quarter-quarter-half and half-quarter-quarter, comprising two-quarter waveplates (QWP) and a half waveplate (HWP) realizing transformation between arbitrary states of polarization (SOP) are investigated using a geometry method in this work. The expressions of azimuths of each waveplate in two polarization transforms are derived in Stokes space. Compared to the matrix treatment methods, the geometry method proposed in this paper is simple and explicit.

The 3p photoabsorption spectra of Ca Ⅲ are analyzed with multichannel quantum defect theory (MQDT). Fitting MQDT parameters to minimize deviation between the observed and theoretical energy values, we have determined the MQDT parameters (μα,Uiα) for J=1 odd-parity MQDT model and using these parameters we predict the energies and Landé g factors of 3p5nd(3/2, 3/2) (7≤n≤31), 3p5nd(3/2, 5/2)(12≤n≤31), 3p5nd(1/2, 3/2)(11≤n≤18), 3p5ns(1/2, 1/2)(12≤n≤19), 3p5ns(3/2, 1/2)(13≤n≤32) and autoionized energy levels of 3p5ns(1/2, 1/2) (20≤n≤24) and 3p5nd(1/2, 3/2)(19≤n≤23). Some assignments of levels are changed.

Suspended gold nanospheres have been synthesized via electrochemical method. UV-vis spectra and fluorescence emission spectra have been studied at room temperature. Numerical calculations based on quasi-static, scattering and local field theories were developed to describe these optical properties. With the increasing dielectric constant of surrounding medium from 1.0 to 2.0, both local field enhancement factor and absorption wavelength maximum red shift in a linear way. However, the wavelength maximum of scattering cross-section depends on the surrounding medium dielectric constant in a nonlinear fashion.

Silver colloidal nanospheres have been synthesized via electrochemical method. The absorption spectrum features show two peaks at 410 and 470nm, which result from transverse and longitudinal surface plasmon resonance, respectively. Two kinds of fluorescence emission peaks are observed. The shorter wavelength peaks fixed at about 315nm are due to the local field enhancement and the longer wavelength peaks red shift with the increasing excitation wavelength, which results from the electron interband transitions.

Suspended gold nanorods with mean aspect ratio 2.5 have been synthesized via electrochemical method. Resonance scattering properties have been studied. Two scattering peaks fixed at 400 and 640nm are due to the scattering of the gold nanorods via coupling to the transverse and longitudinal surface plasmon resonance. The quasi-static calculation results indicate that with the increasing aspect ratio of the nanorods, the longer wavelength scattering peak red shifts linearly and the shorter wavelength peak blue shifts non-linearly. When aspect ratio a/b=1.0, ellipse degenerate to sphere and the two peaks unite into one peak at 450nm.