Влияние способа сильного легирования на композиционную однородность и оптические свойства монокристаллов LiNbO-=SUB=-3-=/SUB=- : Mg

Raman spectroscopy, laser conoscopy and photoinduced light scattering methods have been applied to comparatively study composition uniformity of strongly doped LiNbO3 crystals with a magnesium concentration close to a threshold value ≈5 mol% MgО, grown from a charge synthesized using precursor Nb2O5:Mg (homogeneous doping method) and at direct addition of magnesium to the melt (direct doping method). It has been shown that application of homogeneous doping method allows one to obtain compositionally more homogeneous heavily doped LiNbO3:Mg crystal than direct melt doping method.

Isolamendu molekularrean oinarritutako gas faseko espektroskopiaren abantailak antrazenoan oinarritutako polimeroaren karakterizazioan

Molekulen propietate fisiko-kimikoen jatorria ezagutzea ezinbestekoa da material berrien garapenerako. Hala ere, teknika esperimental konbentzionalen mugak direla eta, aipatutako helburua betetzea ez da erraza. Erronka hau gainditzeko beharrezkoa den zehaztasuna egoera-isolatutako ikasketetan eskuragarri dago. Kasu honetan, konduktantzia altua aurkezten duen antrazeno unitatez osatutako foldameroen familia berriaren propietate intrintsekoak aztertu dira egoera isolatutako RIDIRS (Resonant Ion Dip Infrared Spectroscopy) laser-espektroskopia eta espantsio supersonikoak erabiliz. Modu honetan, isolatutako molekulen berezko infragorri espektro esperimentala eta DFT (Density-functional theory) kalkuluen emaitzak konparatu dira antrazeno monomeroen arteko π-π elkarrekintzen nagusitasuna determinatu ahal izateko. Horren ondorioz, laser-espektroskopia gainerako karakterizazio-teknikentzako osagarri ezinhobea dela egiaztatu da.

Standoff Chemical Detection Using Laser Absorption Spectroscopy: A Review

Remote chemical detection in the atmosphere or some specific space has always been of great interest in many applications for environmental protection and safety. Laser absorption spectroscopy (LAS) is a highly desirable technology, benefiting from high measurement sensitivity, improved spectral selectivity or resolution, fast response and capability of good spatial resolution, multi-species and standoff detection with a non-cooperative target. Numerous LAS-based standoff detection techniques have seen rapid development recently and are reviewed herein, including differential absorption LiDAR, tunable laser absorption spectroscopy, laser photoacoustic spectroscopy, dual comb spectroscopy, laser heterodyne radiometry and active coherent laser absorption spectroscopy. An update of the current status of these various methods is presented, covering their principles, system compositions, features, developments and applications for standoff chemical detection over the last decade. In addition, a performance comparison together with the challenges and opportunities analysis is presented that describes the broad LAS-based techniques within the framework of remote sensing research and their directions of development for meeting potential practical use.

Rapid and Sensitive Analysis of Trace Leads in Medicinal Herbs Using Laser-Induced Breakdown Spectroscopy–Laser-Induced Fluorescence (LIBS-LIF)

Toxic metals in medicinal herbs are potentially harmful for people taking herbal medicines. In this work, laser-induced breakdown spectroscopy–laser-induced fluorescence (LIBS-LIF) spectroscopy was first applied to carry out rapid and sensitive trace lead analysis in medicinal herb samples. To overcome the problem of diversity on the sample size, shape, and density for different samples, original samples were pulverized to powder and then pressed into pellets for spectral analysis. A series of standard samples were self-made for building a calibration curve. As an exemplary study, lead in Rheum officinale was analyzed with LIBS-LIF spectroscopy with significantly improved analytical sensitivity. The R2 of the build linear calibration curve was 0.996 and the detection limit of lead in R. officinale was determined to be 0.13 ppm. The enhancement factor on the signal-to-background ratio was >100 under low lead concentrations if compared with LIBS analysis. The lead concentrations in several original R. officinale samples were quantitatively determined. This work demonstrated that LIBS-LIF can be successfully applied to carry out rapid, sensitive, and quantitative trace lead analysis for medicinal herbs.

Synthesis and photophysical properties of conjugated (dodecyl)benzoateethynylene macromolecules: staining ofBacillus subtilisandEscherichia colirhizobacteria

The staining of agrobacteria was successfully demonstrated through a benzoateethynylene by fluorescence spectroscopy, laser confocal microscopy and microRaman.