Wyniki wyszukiwania - BazTech

1

Structural, spectral, electrical, Z-scan and HOMO LUMO studies on new 2-amino-6-methylpyridinium 2-hydroxybenzoate crystal

Punithaveni B., Thilagavathy K., Muthukumarasamy N., Nithyaprakash D., Saravanabhavan M.

Materials Science Poland

|

2018

|

Vol. 36, No. 4

537--546

EN

New organic single crystals of 2-amino-6-methylpyridinium 2-hydroxybenzoate (2A6M2H) were grown by slow evaporation solution growth technique at room temperature. The grown crystal structure was studied using single crystal XRD. Crystalline nature and phases were confirmed by powder XRD analysis. FT-IR study was used to identify the functional groups present in the compound. UV-Vis study revealed that the lower cut off wavelength of the crystal is at 350 nm. The dielectric studies indicated the low value of dielectric loss at high frequency. Mechanical properties of the crystals were studied using Vickers microhardness test. The Z-Scan studies were conducted for the crystal using He–Ne laser.

2

Wpływ osnowy polimerowej na piezooptykę nanokrystalitów γ-glicyny

Oźga K., Nabiałek M., Szota M., Rakus P., Czaja P., Dośpiał M., Berdowski J., Tylczynski Z.

Przetwórstwo Tworzyw

|

2011

|

[R.] 17, nr 6

483-487

PL

Ustalono główną rolę polarności osnów polimerowych na dyspersję zjawiska piezooptyki nanokrystalitów γ-glicyny wprowadzonych w osnowy polimerowe poli(metakrylanu metylu) (PMMA) oraz poliwęglanu (PC). Stwierdzono pojawienie się efektu piezooptycznego pod wpływem obróbki laserowej dwoma wiązkami świetlnymi o długości fali 1064 nm oraz 532 nm, generowanymi z jednego źródła laserowego YAG: Nd. Optymalne rozmiary nanokrystalitów γ-glicyny, dla których otrzymano odpowiednie wartości współczynników piezooptyczych wynosiły 50-80 nm (optymalna koncentracja 5,5 % w j. wag.). W pracy badano relaksacje oraz zależności spektralne odpowiednich współczynników tensora piezooptycznego.

EN

We have established a principal role of the polarity of polymer matrices on the piezooptical dispersion of the γ-glycine nanocrystallites embedded into the polymethymethacrylate (PMMA) and polycarbonate (PC) matrices. We have found that the optical treatment by bicolor two laser beams at 1064 nm and 532 nm which are originating from the same 10 ns Nd:YAG lasers, causing occurrence of the piezooptical effects. The optimal content of the γ-glycine nanocrystallites with respect to the magnitude of piezooptical coefficients with the sizes within the range 50-80 nm correspondence to the 5.5 % in weighting unit. We studied relaxation and spectral dependences of the corresponding coefficients of piezooptic tensor.

3

Higher-order space charge field effects on the self-deflection of bright screening spatial solitons in two-photon photorefractive crystals

Jiang Q., Su Y., Ji X.

Optica Applicata

|

2010

|

Vol. 40, nr 2

481--490

EN

We investigate the effects of higher-order space charge field on the self-deflection of bright screening spatial solitons due to two-photon photorefractive effects by a numerical method under steady-state conditions. The expression for an induced space charge electric field including higher-order space charge field terms is obtained. Numerical results indicate that bright screening solitons undergo self-deflection process during propagation, and the solitons always bend in the opposite direction of the c axis of the crystal. The self-deflection of bright screening solitons can experience considerable increase especially in the regime of high bias field strengths. Relevant examples are provided.

4

New mid-infrared optical sources based on isotropic semiconductors (zinc selenide and gallium arsenide) using total internal reflection quasi-phase-matching

Haidar R., Kupecek P., Rosencher E., Triboulet R., Lemasson P.

Opto-Electronics Review

|

2003

|

Vol. 11, No. 2

155-160

EN

The French aerospace agency is involved in the realization of compact solid-state coherent sources, such as optical parametric oscillators (OPO), using new materials, such as highly non-linearly efficient semiconductors (ZnSe, GaAs or InP). However, since these materials are optically isotropic, they require new phase-matching techniques. We report the quasi - phase matched difference frequency generation in isotropic semiconductors using total internal reflection. We made use of large Fresnel birefringence at reflection between the signal and idler wave outputs of an OPO. Large tunability (between 8 and 13 um) is demonstrated. Agreement between theoretical expectation and experimental results is excellent.

5

Local Fields and Distributed Response : Electric Susceptibility Calculations for Molecular Materials

Munn R., Papadopoulos M. G, Reis H.

Polish Journal of Chemistry

|

2002

|

Vol. 76 / nr 2-3

155-165

EN

Progress in the last 25 years towards realistic theoretical calculation of linear and non-linear electric susceptibilities of molecular materials is reviewed. Key issues are proper treatment of local electric fields and of the spatial distribution of molecular response. The local fields contribute directly to the susceptibilities and indirectly by modifying the molecular response in the material. Distributing molecular dipolar response over equivalent submolecules gives good results if enough submolecules are used. Fully distributed response including charge transfer within molecules can approach experimental accuracy.

6

On the nature of long-lived photoexcited states in polydiacetylenes : the photoinduced absorption spectra of PDA-4BCMU

Comoretto D., Moggio I., Alloisio M., Cuniberti C., Musso G. F., Ottonelli M., Dellepiane G., Kajzar F., Lorin A.

Opto-Electronics Review

|

1999

|

Vol. 7, No. 2

121-129

EN

We report the results of steady-state photoinduced absorption experiments on PDA-4BCMU grown and oriented silica substrate. A high degree of axial order, checked by linear and nonlinear optical dichroism and correlated with X-ray measurements was found. Polycrystalline films were obtained with a preferential orientation of crystallites. Unlike the solution cast films exhibiting the so called "red form" only, the deposited films are blue thus showing a better π -electron conjugation than in the former case due to a better planarity of polymer chains. The films were used to perform steady-state photoinduced absorption experiments. Three photoinduced absorption bands at 0.82, 0.95, and 1.39 eV were observed. The 0.82 and 0.95 eV absorption features are assigned to charged states while the 1.39 eV peak is originated by triplet excitions. The photogeneration in PDA-4BCMU of both charged and neutral stated is discussed and compared with the results obtained in polydiacetylenes having carbazolyl groups as substituents. The relative weight of one excited species over the other one is dictated by the molecular and supramolecular organization of the polymer.