THz spectra of five borates crystals

Terahertz spectral responses have been studied for five borate crystals Nas[B2P3O13] （NBP）, Zn3BPO （ZBP）, SrB407 （SBO）, Na3LagO3（BO 3）8 （NLBO） and PbB407 （PBO）. It is found that the samples had good transmission in 0.25--1.5 THz region. Both SBO and NLBO have an absorption coefficient less than 10 cm^-1. Among them, SBO has not only the smallest absorption coefficient but also a very flat dispersion in the frequency region under investigation. Distinct resonance absorption peaks are observed for ZBP at v1 = 1.4 THz, v2 = 2.0 THz and SBO at v = 2.4 THz. In the spectrum of PBO, two abnormal dispersions appear in the frequency regions 1.44--1.74 and 2.2--2.5 THz. The absorption coefficients and refraction indices of the five crystals are extracted from the THz time-domain （THz-TDS） spectra in 0.25--2.5 THz region. The properties and origins of the spectral responses are addressed.     

The R- and AR-indices： Complementing the h-index

Based on the foundation laid by the h-index we introduce and study the R- and AR-indices. These new indices eliminate some of the disadvantages of the h-index, especially when they are used in combina-tion with the h-index. The R-index measures the h-core’s citation intensity, while AR goes one step further and takes the age of publications into account. This allows for an index that can actually in-crease and decrease over time. We propose the pair (h, AR) as a meaningful indicator for research evaluation. We further prove a relation characterizing the h-index in the power law model.