Deuterated Triglycine Sulfate Research Articles

Pyroelectric effect and piezoelectric properties of composites based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene) and deuterated triglycine sulfate

In this work, composite films of a copolymer of vinylidene fluoride with trifluoroethylene P(VDF-TrFE) comprising microcrystals of deuterated triglycine sulfate (DTGS) were produced. The pyroelectric properties of the composite samples were studied by the dynamic method. Pyroelectric measurements indicated an extreme dependence of the pyroelectric coefficient on the concentration of DTGS inclusions in the composite. Piezoelectric modules were macroscopically measured in static mode. The measured piezoelectric moduli d 31 and d 33 show ambiguous dependences on the volume fraction of DTGS inclusions.

Double hysteresis loops in deuterated triglycine sulfate after thermal depolarization

The temperature behavior of the hysteresis loops and switching current parameters measured in the increasing field have been studied in single crystals of deuterated triglycine sulfate. We have revealed the hysteresis loops doubling leading to appearance of additional maxima at the field/time dependence of the switching current during cooling from 59.3 to 51.4°С. This effect was attributed to the bias fields arising as a result of bulk screening of depolarization field. Different current maxima corresponded to the switching in the areas with different values of bias field.

Linearity measurement of FTIR infrared spectral emissivity measurement facility determined using flux superposition at NIM

A Fournier-Transform infrared (FTIR) spectrometer using a deuterated triglycine sulfate (DTGS) detector is the radiation detective unit of the infrared spectral emissivity measurement facility of standard reference of P. R. China at NIM. The linearity of the FTIR spectral responsivity in the NIM infrared spectral emissivity measurement facility has a significant contribution to emissivity measurement. The linearity of the FTIR using the DTGS detector is experimentally measured using a flux superposition principle. A linearity measurement system of FTIR spectral responsivity is established using a high- and mid-temperature standard reference cavity blackbody radiation sources, covered the temperature range (373-1373) K. The linearity characteristics are measured in the temperature range of (473∼1273) K of the blackbody radiation sources. The measurement results with the uncertainties at the representative wavelengths of 3.9 μm and 10.6 μm are reported. The associated discussions about the linearity measurement results, including the difference at the two wavelengths, the effects caused by reflection and verifications are carried out. All the measurements in this paper are traceable to NIM.

Investigation of the linearity of the NIM FTIR infrared spectral emissivity measurement facility by means of flux superposition method

The Fourier-Transform infrared (FTIR) spectrometer is a commonly used instrument in infrared radiation measurements. An infrared spectral emissivity measurement facility using a deuterated tri-glycine sulfate (DTGS) detector has been set up at the National Institute of Metrology, China (NIM). The linearity of the spectral responsivity is one of the main uncertainty contributions in spectral-emissivity measurement, performed over a wide spectral radiance range (0–30,000 W/(m2·sr·μm)). Using the flux superposition method, a double-aperture method, where the apertures are positioned precisely by a cage structure, has been used to measure the linearity of the FTIR measurement system, a sub-system of the infrared spectral emissivity measurement facility, developed at NIM. The drift characteristics of the blackbody radiation sources and the FTIR measurement system during a typical linearity measurement have been investigated. Drifts of the blackbody sources are reduced by integration of the spectrum. The quasi-linear drifts of the FTIR measurement system are corrected by inverting the measurement sequence of the apertures. Moreover, corrections for the effects of aperture imperfections on the linearity measurement have been quantified experimentally. Measurements are reported for blackbody radiation sources in the temperature range (473–1273 K), with detection at the wavelengths 3.9 μm and 10.6 μm, respectively.

Tertiary pyroelectric effect in TGS group crystals

In this paper, the study of the dynamic pyroelectric effect under different powers of modulated heat flux in deuterated triglycine sulfate (DTGS) near the Curie point is presented. It was found that pyroelectric coefficient was essentially dependent on the power of the modulated radiation, especially in the phase transition region. It is shown that a tertiary pyroelectric effect makes an additional contribution to the pyroelectric response observed in TGS group crystals near phase transition region. The tertiary pyroelectric effect is caused by a nonuniform distribution of piezoelectric coefficients in the samples as a result of temperature gradient presence.

Empirical demonstration of CO2 detection using macroporous silicon photonic crystals as selective thermal emitters.

This study describes the detection of CO2 using macroporous silicon photonic crystals as thermal emitters. It demonstrates that the reduction of structural nonhomogeneities leads to an improvement of the photonic crystals' emission. Narrow emission bands (Q∼120) located within the R-branch of carbon dioxide were achieved. Measurements were made using a deuterated triglycine sulfate photodetector and the photonic crystals, heated to 400°C, as selective emitters. A gas cell with a CO2 concentration between 0ppm and 10,000ppm was installed in the center. Results show high sensibility and selectivity that could be used in current nondispersive infrared devices for improving their features. These results open the door to narrowband emission in the mid-infrared for spectroscopic gas detection.

Dielectric properties of composite materials based on P(VDF-TrFE) copolymer and deuterated triglicyne sulfate crystal

The film structures on the base of soft and crystalline ferroelectrics (poly(vinylidene fluoride - trifluoroethylene) copolymer and deuterated triglycine sulfate) were produced. The volume content of the DTGS microcrystal particles embedded in the polymer matrix of the composite films was up to 10%. It was found crystalline phase changes in the polymer matrix at the DTGS inclusions presence. The DTGS crystal particles increased dielectric permittivity and electrical conductivity of the composite films. The temperature dependences of the dielectric permittivity indicated increasing the phase transition temperature of polymer matrix at the DTGS inclusions growth.

Focus on analytical equipment, sensors, and instrumentation

Focus on analytical equipment, sensors, and instrumentation

Big bore and extremely flexible mid-infrared hollow waveguide for gas absorption module

Big-bore, low-loss, and extremely flexible hollow waveguides were fabricated for mid-infrared spectroscopic gas sensing. The waveguide with inner/outer diameter of 1.4/2.0 mm can be curved with a bending radius as small as 1.4 cm A module of gas absorption cell for spectroscopic sensing was proposed with the hollow waveguide curved into a channeled substrate. Hollow waveguide with inner coatings of silver and silver iodide films attains low loss in the mid-infrared region for methane gas detection. Sensing properties for the module was experimentally discussed. Limit of detection of 6 ppm was obtained by using an FTIR (Fourier Transform infrared spectroscopy) system and DTGS (deuterated triglycine sulfate) detector. Comparisons were made to metallic hollow waveguide only with silver inner coating.

Material Spectral Emissivity Measurement Based on Two Reference Blackbodies

Spectral emissivity is one of the important physical properties of materials. Emissivity measurement is critical for accurate temperature measurements and the evaluation of the stealth performance for materials. In this paper, a Fourier transform infrared spectrometer and an energy comparison method are used to study material emissivity measurements. Two reference blackbodies are employed for real-time measurement and correction of the spectrometer background function to enhance the emissivity measurement accuracy, to improve the design of a three-parabolic-mirror optical system, and to enlarge the optical field of view to meet the measurement requirements. The linearity of the system is measured using a mercury cadmium telluride detector and a deuterated triglycine sulfate detector. The results indicate that the linear range of the system meets the emissivity measurement requirements for the temperature range from $$50\,^{\circ }\mathrm{C}$$ to $$1000\,^{\circ }\mathrm{C}$$ . The effective radiation surface is introduced as a parameter of the reference blackbodies to reduce the influence of the measurement distance. The Fourier transform infrared spectrometer is used to measure the spectral emissivity of a conductive silica film and SiC, respectively, at different temperatures in the wavelength range of $$1\ \upmu \mathrm{m}$$ to $$25\ \upmu \mathrm{m}$$ . The expanded uncertainty is less than 5 %.

Aminoacid Containing Partially Deuterated Ferroelectrics

In this work we analyze dielectric data for partially deuterated triglycine selenate (TGSe)1-x (DTGSe)x with x = 0, 0.35, 0.80, and partially deuterated triglycine sulfate (TGS)1-x (DTGS)x with x = 0, 0.54, 0.77. The starting data are the Curie temperature, Curie constant and spontaneous polarization at low temperature for various compositions and deuterated compounds. From these data, the effective field coefficient β, the number of elementary dipoles per unit volume N, and the elementary dipole moment μ can be obtained. A slight increase of β with x composition is apparent, while N and μ seem to change very little with deuteration.

Broadband terahertz wave generation from a MgO:LiNbO_3 ridge waveguide pumped by a 15 μm femtosecond fiber laser

Cherenkov phase-matched terahertz (THz) wave generation from a MgO:LiNbO3 ridge waveguide was studied using optical rectification. Pumping was achieved using 20 and 60 fs laser pulses from a fiber laser centered at 1.56 μm. Time-domain spectroscopy (TDS) results showed a single-cycle pulse with 20 fs pulse pumping and a near-single-cycle pulse with 60 fs pulse pumping. The spectrum covered the range of 0.1-7 THz, with a signal-to-noise ratio of over 50 dB. The output power measured by a Si bolometer and a deuterated triglycine sulfate pyroelectric detector is shown and compared to that of a commercial photoconductive antenna. This system is believed to be a promising THz source for low-cost, compact, robust, and highly integrated TDS, THz imaging, and tomography systems.

Identification of Carbonates as Additives in Pressure‐Sensitive Adhesive Tape Substrate with Fourier Transform Infrared Spectroscopy (FTIR) and Its Application in Three Explosive Cases

Pressure-sensitive tape is often used to bind explosive devices. It can become important trace evidence in many cases. Three types of calcium carbonate (heavy, light, and active CaCO(3)), which were widely used as additives in pressure-sensitive tape substrate, were analyzed with Fourier transform infrared spectroscopy (FTIR) in this study. A Spectrum GX 2000 system with a diamond anvil cell and a deuterated triglycine sulfate detector was employed for IR observation. Background was subtracted for every measurement, and triplicate tests were performed. Differences in positions of main peaks and the corresponding functional groups were investigated. Heavy CaCO(3) could be identified from the two absorptions near 873 and 855/cm, while light CaCO(3) only has one peak near 873/cm because of the low content of aragonite. Active CaCO(3) could be identified from the absorptions in the 2800-2900/cm region because of the existence of organic compounds. Tiny but indicative changes in the 878-853/cm region were found in the spectra of CaCO(3) with different content of aragonite and calcite. CaCO(3) in pressure-sensitive tape, which cannot be differentiated by scanning electron microscope/energy dispersive X-ray spectrometer and thermal analysis, can be easily identified using FTIR. The findings were successfully applied to three specific explosive cases and would be helpful in finding the possible source of explosive devices in future cases.

Novel Lipofuscin Bisretinoids Prominent in Human Retina and in a Model of Recessive Stargardt Disease

Bisretinoid adducts accumulate as lipofuscin in retinal pigment epithelial (RPE) cells of the eye and are implicated in the pathology of inherited and age-related macular degeneration. Characterization of the bisretinoids A2E and the all-trans-retinal dimer series has shown that these pigments form from reactions in photoreceptor cell outer segments that involve all-trans-retinal, the product of photoisomerization of the visual chromophore 11-cis-retinal. Here we have identified two related but previously unknown RPE lipofuscin compounds. By high performance liquid chromatography-electrospray ionization-tandem mass spectrometry, we determined that the first of these compounds is a phosphatidyl-dihydropyridine bisretinoid; to indicate this structure and its formation from two vitamin A-aldehyde (A2), we will refer to it as A2-dihydropyridine-phosphatidylethanolamine (A2-DHP-PE). The second pigment, A2-dihydropyridine-ethanolamine, forms from phosphate hydrolysis of A2-DHP-PE. The structure of A2-DHP-PE was corroborated by Fourier transform infrared spectroscopy, and density functional theory confirmed the presence of a dihydropyridine ring. This lipofuscin pigment is a fluorescent compound with absorbance maxima at approximately 490 and 330 nm, and it was identified in human, mouse, and bovine eyes. We found that A2-DHP-PE forms in reaction mixtures of all-trans-retinal and phosphatidylethanolamine, and in mouse eyecups we observed an age-related accumulation. As compared with wild-type mice, A2-DHP-PE is more abundant in mice with a null mutation in Abca4 (ATP-binding cassette transporter 4), the gene causative for recessive Stargardt macular degeneration. Efforts to clarify the composition of RPE lipofuscin are important because these compounds are targets of gene-based and drug therapies that aim to alleviate ABCA4-related retinal disease.

Infrared studies at the ice laboratory of Alcoy

At present, there are few laboratory spectra of analogs of astrophysical interest in the far-infrared range (FIR). Laboratory infrared (IR) spectra of simple ices and its mixtures obtained at low temperature and pressure are found mainly up to 25 μm, and few up to 200 μm. On the other hand, there are some spectra for carbonaceous material and silicates up to 2000 μm. Our laboratory is equipped with an IR spectrometer that integrates a Michelson interferometer with a resolution better than 0.25 cm −1 and that operates under vacuum conditions of 10 −1 mbar. There is also a silicon bolometer, a very high-sensitivity detector in comparison with the standard deuterated triglycine sulfate (DTGS) detectors. The use of the bolometer and the possibility of working under vacuum conditions inside the optics and the sample compartment of the spectrometer allow obtaining high-sensitivity spectra free from H 2O vapor and CO 2 gas bands. Those conditions are necessary to obtain high-quality spectra in the FIR where absorption bands are much less intense than those in the mid-IR region. In our laboratory there is also a high-vacuum chamber that allows different studies on ices deposited onto a cold finger. We have already carried out experiments on the study of ice density as a function of temperature, UV irradiation of ices, temperature-programmed desorption (TPD) and UV–vis reflectance. In this work, we present the design of the experimental setup we are building to carry out different experiments simultaneously on the same ice sample, including spectra measurements in the mid-IR range (MIR) and the FIR. This design integrates jointly the IR spectrometer, the high-vacuum chamber and the silicon bolometer. Lastly, we show a spectrum we have obtained of a solid of astrophysical interest such as crystalline forsterite grains by using the polyethylene pellet technique.

The Secondary Structure of Calcineurin Regulatory Region and Conformational Change Induced by Calcium/Calmodulin Binding

The protein serine/threonine phosphatase calcineurin (CN) is activated by calmodulin (CaM) in response to intracellular calcium mobilization. A widely accepted model for CN activation involves displacement of the CN autoinhibitory peptide (CN(467-486)) from the active site upon binding of CaM. However, CN activation requires calcium binding both to the low affinity sites of CNB and to CaM, and previous studies did not dissect the individual contributions of CNB and CaM to displacement of the autoinhibitory peptide from the active site. In this work we have produced separate CN fragments corresponding to the CNA regulatory region (CNRR(381-521), residues 381-521), the CNA catalytic domain truncated at residue 341, and the CNA-CNB heterodimer with CNA truncated at residue 380 immediately after the CNB binding helix. We show that the separately expressed regulatory region retains its ability to inhibit CN phosphatase activity of the truncated CN341 and CN380 and that the inhibition can be reversed by calcium/CaM binding. Tryptophan fluorescence quenching measurements further indicate that the isolated regulatory region inhibits CN activity by occluding the catalytic site and that CaM binding exposes the catalytic site. The results provide new support for a model in which calcium binding to CNB enables CaM binding to the CNA regulatory region, and CaM binding then instructs an activating conformational change of the regulatory region that does not depend further on CNB. Moreover, the secondary structural content of the CNRR(381-521) was tentatively addressed by Fourier transform infrared spectroscopy. The results indicate that the secondary structure of CNRR(381-521) fragment is predominantly random coil, but with significant amount of beta-strand and alpha-helix structures.

High-power terahertz-wave generation using DAST crystal and detection using mid-infrared powermeter

The exact power output of a table-top-sized terahertz (THz)-wave source using a nonlinear optical process has not been clarified because detectors for these experiments [Si bolometer, deuterated triglycine sulfate (DTGS), etc.] are not calibrated well. On the other hand, powermeters for the mid-infrared (mid-IR) region are well established and calibrated. We constructed a high-power dual-wavelength optical parametric oscillator with two KTP crystals as a light source for difference frequency generation. The obtained powers of dual waves were 21 mJ at ~1300 nm, ten times higher than that of the previous measurement. The device provides high-power THz-wave generation with ~100 times greater output power than that reported in previous works. A well-calibrated mid-IR powermeter at ~27 THz detected the generated THz wave; its measured energy was 2.4 microJ. Although the powermeter had no sensitivity in the lower-frequency range (below 20 THz), the pulse energy at such a low-frequency region was estimated in reference to the output spectrum obtained using a DTGS detector: the energy would be from about the submicrojoule level to a few microjoules in the THz-wave region.

Optical studies of ferroelectric phase transition in deuterated triglycine sulfate crystals

We report on precise experimental measurements with the Senarmont technique of optical birefringence in partly deuterated triglycine sulfate crystals (DTGS, deuteration degree x ≈ 0.7) and interpretation of the influence of ferroelectric phase transition (PT) on the birefringence. The critical phenomena observed, not too close to the PT point, are quantitatively analysed. The fluctuation effects are shown to be fairly well described in terms of the approach of first fluctuation correction to the Landau theory. We have derived spontaneous electrooptic characteristics of DTGS and revealed that deuteration improves those characteristics.

Domain Structure and Pyroelectric Effect in the Presence of Temperature Gradient in Ferroelectrics

A study is made demonstrating that in deuterated triglycine sulfate crystals the maximum pyrocoefficient value measured simultaneously by quasistatic and dynamic methods decreases with the increase of the heat flux power. For dynamic measurements the position and magnitude of the pyrocurrent maximum depend on the heat flux density. This behaviour of the pyroresponse is explained by the instability of the monodomain state and depolarization of the crystal surface layer.

Polarization switching of triglycine sulfate and deuterated triglycine sulfate single crystals irradiated with a high-current pulsed electron beam

The influence of high-current pulsed electron beams on the processes of polarization switching in triglycine sulfate and deuterated triglycine sulfate single crystals is investigated using the Barkhausen effect.