SHG Technique Research Articles

Crystal growth, Hirshfeld surface, quantum chemical calculations, optical, photoluminescence and thermal analyses of sodium D-isoascorbate monohydrate single crystal

The metal-organic sodium D-isoascorbate monohydrate (NDAM) crystal was from grown slow evaporation technique. The NDAM crystal belongs to an orthorhombic crystal system. The vibrational assignments of NDAM molecules were found using FTIR and FT-Raman studies. The predominant O…H interactions are observed in the dnorm surface. The calculated dipole moment (μ) of the NDAM molecule is 4.4837 Debye. The chemical hardness of the title molecule is found to be 1.5405 eV. The isoascorbate ring moiety contains the HOMO value of NDAM. The highest Mulliken charge value was observed in Na8 (+0.6439). The fragment orbitals O, N, H, and C are donated to the formation of the molecular orbital. The H atoms have the strongest attraction. The NBO is used to calculate the stabilization energy of inter and intramolecular interactions of NDAM. The SHG behaviour of NDAM crystal was confirmed using Kurtz powder SHG technique. The emission was observed between 350 and 580 nm. The thermal studies of the NDAM crystal were found by TGA/DTG analysis.

Synthesis, growth, structural, optical, thermal and NLO studies of new organic single crystal: 3-Hydroxy pyridinium 2-hydroxy benzoate

• The present molecular complex is crystallized in the space group of P2 1 2 1 2 1 . • The emission peak observed at 415 nm in PL spectrum indicates blue emission. • The SHG efficiency of the present crystal is 1.6 times higher than that of KDP. • The present crystal is thermally stable upto 224°C. • Hirshfeld surface analysis illustrates that O•••H interactions are more prominent. The single crystal of 3-hydroxy pyridinium 2-hydroxy benzoate (3HP2HB) molecular complex was grown by solution growth method. The conformation of crystal structure was done by single crystal X-ray diffraction (SCXRD) technique and it uncovers that the title crystal belongs to orthorhombic crystal system with P2 1 2 1 2 1 space group. The absorption spectrum of grown crystal was recorded using UV–Vis spectroscopy. Fluorescence emission spectrum was observed in the blue band region using spectroflurometer. 1 H and 13 C NMR spectral technique was used to predict the presence of hydrogen and carbon bonded network. The Fourier transform infrared spectral technique (FT-IR) was used to identify the presence of various functional groups in the crystal structure. The second order nonlinear optical property of the crystal was studied by the modify Kurtz-Perry powder SHG technique using Nd:YAG laser with wavelength 1064 nm. The thermal stability of the title crystal was carried out by TG/DTA studies. The presence of inter-molecular interactions was examined by Hirshfeld surface. The DFT method was used with B3LYP/6-311++G(d,p) basis set to compute the structural, electronic and reactivity properties of the title crystal.

D-π-A chromophores with a quinoxaline core in the π-bridge and bulky aryl groups in the acceptor: Synthesis, properties, and femtosecond nonlinear optical activity of the chromophore/PMMA guest-host materials

Novel D-π-A chromophores with quinoxaline/quinoxalinone core in the π-conjugated bridge and various bulky groups in the acceptor moiety have been synthesized and systematically investigated at molecular level by UV–Vis spectroscopy, DFT calculations, electrochemical and TGA-DSC methods as well as at materials level by the example of PMMA-based composite polymer materials doped with different chromophore contents using molecular modeling and SHG technique. Chromophores exhibit positive dioxane/chloroform solvatochromic shift of ca. 50 nm, high values of first hyperpolarizability and dipole moment, small energy gap and good thermal stability. Tolyl and cyclohexylphenyl substituents unlike phenyl can be treated as most effective isolating groups, preventing chromophore pronounced aggregation even at 30 wt% content. Femtosecond nonlinear optical (NLO) activity was studied for poled thin guest-host polymer films with various chromophore weight content. Film DBA-VQPhV-TCFPhCy(25 wt%)/PMMA with bulky cyclohexylphenyl groups in chromophore acceptor shows maximal NLO coefficient, d33, values among the studied materials (37 pm/V) as well as good long-term stability of NLO response together with excellent chromophore thermal stability (Td = 256 °C). Composite materials doped with quinoxaline chromophores are photostable with respect to laser pulses with peak intensities up to 11 GW/cm2.

Development of High-Efficiency UV Laser Generated by SHG Technique with Primary Visible Fiber Laser

Development of High-Efficiency UV Laser Generated by SHG Technique with Primary Visible Fiber Laser

Structural, Optical and Dielectric Characterization of Guanidine Acrylate (GuAcr) NLO Single Crystals

Organic single crystal of Guanidine Acrylate (GuAcr) was grown by simple inexpensive slow evaporation technique. The grown crystal was subjected into various characterizations like single crystal XRD, UV-Vis, FTIR studies, electrical, mechanical properties and SHG technique. The XRD data shows that the crystal belongs to orthorhombic structure. The UV-Vis spectral studies observed that the cutoff wavelength of the grown crystal is 320nm. Optical band gap of the grown crystal was also calculated, and it was found to be 3.99 eV. Vibrational frequencies of GuAcr crystal were confirmed by FTIR spectra. Electrical properties of the GuAcr single crystals were studied using impedance spectroscopy. Decreasing impedance with increasing temperature is indicated that the negative temperature co-efficient of resistance behavior like an insulator. Dielectric response of the crystal with varying frequencies was also studied. Second harmonic generation of the title compound was studied using Kurtz Perry- powder SHG technique. It reveals that as grown crystal is suitable for Nonlinear Optical (NLO) device fabrications.

Large nonlinear optical activity of chromophores with divinylquinoxaline conjugated π-bridge

Two chromophores with π-deficient quinoxaline (Q) core in the π-electron bridge together with dibutylaniline (DBA) donor moiety and tricyanofuranyl (TCF) or dicyanovinyl (DCV) acceptor moieties have been synthesized to investigate their macroscopic nonlinear optical (NLO) activity in guest-host materials. A distinctive feature of the 7-DBA-VQPhV-TCF chromophore is predominance of negative solvatochromism over the positive one, which is quite rarely met for the chromophores manifesting inverse solvatochromic behavior as well as the blue shift of the absorption maximum compared to the chromophore FTC with divinylthiophene π-bridge. Introduction of quinoxaline moiety in the conjugated bridge promotes the increase of thermal stability: Td of both compounds is higher than 225 °C. Density functional theory was used to calculate the chromophores first hyperpolarizability (β). Quadratic NLO response characterized by d33 coefficient was measured by SHG technique for thin guest-host polymer films. The influence of chromophore content on the NLO coefficient of 7-DBA-VQPhV-TCF/PMMA film has been investigated and the d33 value of this film reaches 108 pm/V at 25 wt% load. The poled film 7-DBA-VQPh-DCV/PMMA shows twice smaller d33 values (30 pm/V) at the same chromophore load (20 wt%).

Investigation of Electric Field–Induced Structural Changes at Fe-Doped SrTiO3 Anode Interfaces by Second Harmonic Generation

We report on the detection of electric field–induced second harmonic generation (EFISHG) from the anode interfaces of reduced and oxidized Fe-doped SrTiO3 (Fe:STO) single crystals. For the reduced crystal, we observe steady enhancements of the susceptibility components as the imposed dc-voltage increases. The enhancements are attributed to a field-stabilized electrostriction, leading to Fe:Ti-O bond stretching and bending in Fe:Ti-O6 octahedra. For the oxidized crystal, no obvious structural changes are observed below 16 kV/cm. Above 16 kV/cm, a sharp enhancement of the susceptibilities occurs due to local electrostrictive deformations in response to oxygen vacancy migrations away from the anode. Differences between the reduced and oxidized crystals are explained by their relative oxygen vacancy and free carrier concentrations which alter internal electric fields present at the Pt/Fe:STO interfaces. Our results show that the optical SHG technique is a powerful tool for detecting structural changes near perovskite-based oxide interfaces due to field-driven oxygen vacancy migration.

Synthesis, crystal growth, thermal and spectroscopic studies of acentric materials constructed from aminopyridines and 4-nitrophenol

A series of single co-crystals of non-centrosymmetric complexes of different mono- and diaminopyridines, namely 4-aminopyridine, 3,4-diaminopyridine, 2-amino-6-methylpyridine, 2,6-diaminopyridine, 2-aminopyridine, with 4-nitrophenol were grown by slow evaporation technique from solution at constant temperature. Optical transparency in the region of 300–1100nm was found to be suitable for nonlinear optical applications with cut off wavelengths at 420–474nm for these co-crystals. Single crystal X-ray analysis confirms the non-centrosymmetric packing. Thermogravimetric and differential thermal analysis shows good thermal stability of the studied compounds with melting point at range 99–172°C for different co-crystals. The second harmonic generation efficiency has been measured on single crystals by comparative SHG technique relative to KTP crystal. The nonlinear optical coefficient of the compounds was found to be up to 39pm/V.

Investigation on growth, structure and characterization of succinate salt of 8-hydroxyquinoline: An organic NLO crystal

8-Hydroxyquinolinium succinate (8-HQSU) has been synthesized and single crystals were grown from ethanol solvent by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated by single crystal X-ray diffraction analysis. It reveals that 8-HQSU crystallizes in monoclinic system with non-centro symmetric space group P21. FTIR, 1H and 13C NMR spectral investigations have been carried out to identify the vibrational modes of various functional groups and placement of proton and carbon in the 8-HQSU compound, respectively. UV–vis–NIR transmission spectrum shows the cutoff wavelength around 357nm. In addition, a photoluminescence spectral analysis was carried out for 8-HQSU crystals. The thermal properties of crystals were evaluated from TGA and DTA techniques and the crystal was found to be stable up to 145°C. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Photoconductivity studies were carried out on the grown crystals it reveals the positive photo conducting nature. Powder second harmonic generation property of the crystal was confirmed by Kurtz and Perry powder SHG technique and it is found to be 1.3 times greater than that of KDP.

Investigation of carrier transit motion in PCDTBT by optical SHG technique

We analyze the carrier transit behavior in poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazole)] (PCDTBT), which has been reported as a donor material for efficient bulk heterojunction photovoltaic devices. The transfer and transient carrier mobilities in the PCDTBT thin films have been measured and analyzed. The transfer mobility has been measured by the transfer curve of the OFET, whereas the transient mobility is recorded using a time-resolved electric field-induced optical second harmonic generation (TRM-SHG) technique. Using the TRM-SHG technique, the dynamic motion of the charge carriers in the PCDTBT thin films has been directly visualized. We anticipate that the analysis of the carrier motion by TRM-SHG will be effective for the understanding of carrier behavior in PCDTBT thin film and will help to make further improvements in the efficiency of the PCDTBT-based photovoltaic devices.

Synthesis, crystal growth and spectroscopic investigation of second order organic nonlinear optical single crystal: 2-Chloro-N-[4-(dimethylamino)benzylidene]aniline

Organic nonlinear optical (NLO) crystal 2-chloro-N-[4-(dimethylamino)benzylidene]aniline (2Cl4DBA) was synthesized and grown by restricted slow evaporation technique at room temperature using acetone as solvent with good degree of transparency. The lattice parameters were determined and found to be noncentrosymmetric orthorhombic system by single crystal X-ray diffraction. The crystalline nature of the synthesized material was recorded by the powder X-ray diffraction pattern. Molecular structure of the grown crystal was investigated by 1H and 13C NMR and functional groups were identified by FTIR spectrum analysis. The optical absorbance of the grown crystal was ascertained by recording UV–Visible spectrum. Thermal and physiochemical stability of the grown material was investigated by TG/DTA analysis. SHG efficiency was determined by Kurtz–Perry Powder SHG technique and found to be 4.2 and 1.54 times greater that of standard KDP and urea crystals respectively.

The IR temperature studies of phase transition of 4-aminopyridinium-hydrogen maleate-maleic acid: Isotopic effect and nonlinear optical properties

[4-NH2C5H4NH][C4H3O4][C4H4O4] (abbreviated as APM) and its N,O-deuterated analogue have been synthesized. The single-crystal X-ray diffraction studies for N,O-deuterated analogue are reported. The Kurtz and Perry powder SHG technique confirms the second order nonlinear optical properties of APM. The structural phase transition of APM occurring at 312K has been examined by infrared spectroscopy. The infrared temperature studies on the polycrystalline APM showed that the modes arising from NH⋯O and OH⋯O intermolecular hydrogen bonds vibrations appear to be very sensitive to the structural phase transition. The molecular mechanism of the phase transition is explained in terms of significant changes in the hydrogen bond configuration.

Synthesis, growth and spectral studies of S-benzyl isothiouronium nitrate by density functional methods

S-benzyl isothiouronium nitrate (SBTN), was synthesized and characterized by X-ray diffraction, FTIR, UV–Vis and NMR spectra. The Centro-symmetric single crystal of S-benzyl isothiouronium nitrate (SBTN), which crystallizes in monoclinic crystal system with space group P21/C, exhibits second order non-linear optical (NLO) susceptibility, due to intermolecular charge transfer. S-benzyl isothiouronium ion forms well defined charge transfer (CT) salt with anion nitrate through N–H⋯O and C–H⋯O hydrogen bonds. It is to identify the direction of specific N–H⋯O hydrogen bond between the –NH2 group and O− in the anion and also sacking in the solid state responsible for NLO activity in this crystal. The SHG technique confirms the non-linear optical property of the grown crystals. Density functional theory (DFT) calculation has been carried out to study the nature of hydrogen involved in the SBTN crystal. The bond lengths and bond angles of the structure of SBTN crystal calculated using B3LYP method with 6-311+(2d,2p) basis set. These calculations are compared with experimental values to provide deep insight into its electronic structure and property of grown crystal.

Synthesis, nucleation, growth, structural, spectral, thermal, linear and nonlinear optical studies of novel organic NLO crystal: 4-fluoro 4-nitrostilbene (FONS)

A novel organic nonlinear optical material 4-fluoro 4-nitrostilbene (FONS), with molecular formula (C14H10FNO2) has been synthesized. Using ethyl methyl ketone as solvent, the synthesized material has been repeatedly recrystallized to minimize the impurities and good optical quality single crystals were harvested by slow evaporation method. Single crystal X-ray diffraction analysis reveals that the grown FONS crystal belongs to monoclinic system with noncentrosymmetric space group “P21”. The powder X-ray diffraction pattern of FONS has been recorded. Functional groups of the title compound were confirmed by FTIR and the molecular structure was confirmed by 1HNMR. The UV–vis–NIR absorption study reveals no absorption in the visible region and the cut-off wavelength was found to be at 408nm. Optical band gap (Eg) of the grown crystal was found to be 3.27eV and also the optical constants were determined. Thermal behaviour of the FONS has been studied by TGA/DTA analyses. From the mass spectrum, the ratio of compound formation of FONS was analyzed. The NLO property has been confirmed by Kurtz and Perry powder SHG technique and the SHG efficiency of FONS (262mV) crystal was found to be 12 times greater than that of KDP (21.7mV).

Effect of Substituent Position on the Properties of Chalcone Isomer Single Crystals

This paper summarizes the synthesis, growth and the effect of the position of the substituent in the thienyl ring and also the properties of the grown chalcone crystals, 2-CTP and 3-CTP. The formation of compound is confirmed by the re- corded H1NMR spectra. A FT-IR spectrum confirms the presence of all functional groups in both of the crystals. Single crystal XRD reports that even though these two compounds crystallize in monoclinic crystal system, 2-CTP has centro- symmetric P21/c space group and 3-CTP has non-centrosymmetric space group P21. Thermal properties of grown crys- tals analyzed by TG/DTA study explain that the 3-CTP compound is slightly more stable than 2-CTP. The transparency of these isomers in the vis-IR region has been studied. Second and third order nonlinear optical properties of 3-CTP and 2-CTP crystals have been investigated by powder SHG and Z-scan technique respectively.

Synthesis, structural, optical and thermal studies of an organic nonlinear optical 4-aminopyridinium maleate single crystal

Synthesis and growth of a novel organic nonlinear optical (NLO) crystal of 4-aminopyridinium maleate (4APM) in larger size by the slow evaporation solution growth technique are reported. Single crystal and powder X-ray diffraction analyses reveal that 4APM crystallizes in monoclinic system with space group P21 with cell parameters a=8.140(4)Å, b=5.457(5)Å, c=10.926(10)Å and volume=481.4(7)Å3. The grown crystal has been characterized by Fourier transform infrared and UV–visible spectral analyses. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been carried out to study its thermal properties. Dielectric measurements have been carried out to study the distribution of charges within the crystal. The mechanical strength of the crystal has been studied by using Vickers’ microhardness test. The etching studies have been carried out on the grown crystal. The Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal and the SHG efficiency of 4APM was found to be 4.8 times greater than that of KDP crystal.

Studies on the nonlinear optical single crystal: Ammonium d,l-tartrate (C4H9NO6)

The organic nonlinear optical material ammonium d,l-tartrate single crystal has been successfully grown by slow evaporation solution technique (SEST). The grown crystals were characterized by single crystal XRD and the lattice parameters have been confirmed. The structural perfection of the grown crystal was analyzed by high-resolution X-ray diffraction measurement. The optical transmittance spectrum shows that the material has a good optical transparency in the entire visible region with the UV cut-off wavelength at 234nm. Thermogravimetric and differential scanning calorimetric measurements were performed to study the thermal properties of the grown crystal. Chemical etching studies were attempted to determine the dislocation density of the grown crystal. Mechanical behavior was assessed using Vickers hardness testing carried out on (001) crystallographic plane. The Kurtz–Perry powder SHG technique confirms the NLO property of the grown crystal and the efficiency of AMT crystal was found to be 1.3 times that of standard KDP crystal.

Single crystal growth and properties of semiorganic nonlinear optical L‐arginine hydrochloride monohydrate crystals

AbstractL‐arginine hydrochloride monohydrate (LAHCl.H2O) has been synthesized and single crystals have been grown from its aqueous solution by slow evaporation and slow cooling methods. The solubility of the material was measured at various temperatures and bulk crystals of size 26×13×11 mm3 have been grown by optimizing the growth parameters. The grown crystals have been subjected to single crystal XRD studies to confirm the structure and to estimate the lattice parameters. FTIR analysis indicate the mode of vibrations of different molecular groups present in LAHCl and confirm the protonation of guanidyl, amino groups and deprotonation of COO‐ groups. UV‐Vis transmission spectrum revealed the linear optical properties of the grown crystals with a transparency of 65% over the entire visible range upto 300 nm. Thermal behavior of the grown crystal was investigated from DTA and TGA measurements. Dielectric studies have been carried out on the grown crystals. Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal. The SHG efficiency of LAHCl was found to be 0.38 with respect to KDP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Hydrothermal crystal growth of ABe2BO3F2 (A=K, Rb, Cs, Tl) NLO crystals

Abstract Crystals of a family of compounds, ABe 2 BO 3 F 2 (ABBF, A=K, Rb, Cs, Tl), have been grown hydrothermally. Each of these materials was studied using the powder SHG technique and exhibited promising NLO behavior. Seeded crystal growth was demonstrated and the growth conditions were optimized by modifying the temperature, thermal gradient and mineralizer concentration. RbBe 2 BO 3 F 2 crystals possessed a particularly good combination of SHG intensity, favorable crystal habit and fast growth rates. High quality crystals suitable for advanced deep-UV NLO studies were grown at rates of 0.11 mm/day on (0 0 1) and 0.12 mm/day perpendicular to (0 0 1).

Effects of Counterions on Molecular Transport Across Liposome Bilayer: Probed by Second Harmonic Generation

The transport rate of an organic cation, malachite green (MG), across a unilamellar bilayer (∼105 nm) of the dioleoylphosphatidylglycerol (DOPG) liposome has been studied by the SHG technique. This is the first time to our knowledge that the effects of anions on molecular cation transport have been observed. Our studies show four results. First, in the presence of sodium chloride (NaCl) or sodium bromide (NaBr), the time constant for transport of MG across the DOPG bilayer increases with the increase in the concentration of the counterion (i.e., Cl- or Br-). Second, with the organic electrolytes, sodium citrate (NaCitrate) and sodium ethanesulfonate (NaEtSO3), the transport rate is independent of the concentration of the counterion (i.e., Citrate- and EtSO3-). Third, at the same counterion concentration, the transport rate depends on the species of the counterion used. The rate of MG transport is the slowest with Cl-, faster with Br-, and the fastest with the two organic counterions, Citrate- and EtSO3-. ...