Theoretical Study on the Structural and Optoelectronic Properties of the Linear Perfluorooctane Sulfonate (PFOS)

The perfluoroalkyl substances（PFS） have attracted considerable attention in recent years as a persistent global pollutant to be able to bioaccumulate in higher organisms.In this paper,theoretical analysis on electronic structures,optoelectronic properties and absorption spectra properties of the perflurooctane sulfonate（PFOS） in gas phase have been investigated by using the DFT/TD-DFT method.The geometric structures,electrostatic potentials,energy gaps,ionization potentials,electron affinities,frontier molecular orbital,excitation energies and absorption spectra for the ground state of PFOS were calculated.The result indicates that the ability of accepting electron of neutral PFOS is larger than that of anionic PFOS,while the electron excited by UV irradiation from HOMO to LUMO in the anionic PFOS is easier than that in the neutral PFOS.

Structures,Aromaticity and Raman Spectroscopy of Double Hanging Ring Molecules[(GnHn-1^m)(GnHn-1^m)](G=C,Si,Ge;n=3,5,6,7,8;m=+1,-1,0,+1,+2)

Theoretical calculations of Double Hanging Ring Molecule(DHRM) [(GnHn-1^m)(GnHn-1^m)](G=C,Si,Ge;n=3,5,6,7,8;m=+1,-1,0,+1,+2) were performed via Gaussian 09 with the method of Density Functional Theory(DFT). Geometrical optimization, Potential Energy surface Scan(PES), Degree of Aromaticity(DOA) and Nucleus Independent Chemical Shift(NICS) were computed to study the optimal structures and aromaticity of DHRMs. Ring Stretching Vibration Raman Spectroscopy(RSVRSF) was predicted to seek the relation between RSVRSF and aromaticity of DHRMs. The results show optimal structures of DHRMs[(GnH(n-1)~m)(GnH(n–1)~m)](n = 3, 5~8);DA = 90° is the stable structure when n = 3, 7, 8;while n = 5 corresponds to DA = 30°, n = 6 corresponds to DA = 50°;the correlation between DOA and NICS of DHRMs is quadratic;the value of RSVRSF of DHRM approximates to its corresponding single ring molecule, which could act as characteristic frequency of ring molecule to identify its aromaticity;the correlation between RSVRSF and DOA is quadratic, and that between RSVRSF and NICS is linear.

The Status of Ammonia(NH_3) Emissions and Achievements of Emissions Reduction Technology in Farmland Ecosystems

NH3 is one of the leading causes of grey haze, and one of the main causes of serious ecological imbalances that result in environmental problems such as acid rain and air quality deterioration. At present, excessive fertilizer application greatly intensifies NH3 emissions intensity on farmland. In order to understand status and achievements of research on farmland NH3 emissions, the literature of farmland NH3 emission-related studies was retrieved from SCl journals and the Chinese science citation database. These are summarized with respect to the research progress on NH3 emission factors and emission reduction technologies. The future research direction of field NH3 emission and emission reduction technology need to strengthen the field observation on different soil environment and crop types, and understand the effect of NH3 emission on fertilizer application period and the proportion, temperature and organic fertilizer management in farmland mainly. The research results can provide more information about the factors that influence NH3 emissions. This study offers theoretical guidance and support directed at mitigating farmland NH3 emissions in the future.

DFT study on nonlinear optical properties of lithium-doped corannulene

The effects of lithium doping on the nonlinear optical properties of new electrodes (lithium-doped corannulene) were investigated in detail. Nine dynamically stable geometries of Lin-C20H10 (n=1, 2) are predicted by B3LYP/6-31G(d,p). Among these nine structures, the largest first static hyperpolarizability (β0) is computed to be 15314 au, which is dramatically larger than the β0 value of 74 au for C20H10, indicating that Li doping plays an important role in elevating the first hyperpolarizability of corannulene.