Thallium Acid Phthalate Research Articles

L-shell spectroscopy of neon and fluorine like copper ions from laser produced plasma

Ne, F, and O-like Rydberg resonance lines along with some of the inner shell satellite lines of Copper plasma, in the wavelength range of 7.9–9.5 Å, are experimentally observed using a thallium acid phthalate crystal spectrometer. The plasma is produced by the irradiation of a Cu target with a 15 J, 500 ps Nd: Glass laser with a focusable intensity up to 5 × 1014 W/cm2. The observed lines result from the transitions among 2p-nd, 2p-ns, and 2s-nd (n = 4–6) levels. Transition wavelengths, transition probabilities, and oscillator strengths of these lines are calculated using the Multi-Configuration Dirac-Fock method. In this computation, the contribution of relativistic corrections such as two-body Breit corrections and QED corrections due to vacuum polarization and self-energy has also been considered. FLYCHK simulations are used to analyze the distribution of the various charge states of the Copper ions and to find the temperature and density of plasma. Moreover, the effect of self-absorption of the plasma (opacity), as well as of suprathermal electrons on charge state distribution of ions, is also studied. The synthetic spectrum provides a best-match with the experimental spectrum at a laser intensity of 1.3 × 1014 W/cm2 for Tc = 150 eV, Th = 1000 eV, f = 0.008, and density 4.5 × 1020 cm−3.The temperature and density ranges are also calculated using a radiative hydrodynamic code. The calculated temperature and density range are in agreement with the experimentally determined values. The effect of the change in laser intensity on the L-shell spectrum of Cu is studied which indicates the switching between lower (Cu XX) and higher charge states (Cu XXI and Cu XXII) at higher laser intensities.

A Monochromatic Soft X-ray Generation from Femtosecond Laser-produced Plasma with Aluminum

A tabletop ultrafast soft x-ray has been generated from the laser-produce plasma with a femtosecond pulsed Ti:Sapphire laser. The estimated total flux of Al Kα is of 2.2 × 109 photons/sec in 4π radian and the parameters related to the optical performance were obtained. The tungsten/silicon multilayer, flat quartz and bent thallium acid phthalate (TLAP) crystal were used for monochromatization of soft x-ray to refine the aluminum Kα radiation and compared the respective value of E/ΔE. To estimate the size of the x-ray source beam generated by a fs laser, the approximation using the FWHM obtained from the x-ray beam scan near the focal point was discussed, and the size of the diameter was about 9.76 μm.

A Practical Method for Accurate Measurement of Trace Level Fluorine in Mg‐ and Fe‐Bearing Minerals and Glasses Using Electron Probe Microanalysis

Fluorine plays an important role in magmatic and hydrothermal processes, but due to its low abundance in geological samples determining F is difficult by electron probe microanalysis. By using a W‐Si multi‐layered pseudocrystal as the diffraction crystal instead of thallium acid phthalate (TAP), count rates were considerably higher, which however introduced spectral interferences between FKα and FeLα and MgKβ lines when normal integral mode is applied. In this study, we developed a protocol using a W‐Si multi‐layered pseudocrystal for measuring accurately trace level F in both minerals and glasses. First, we used differential mode with an optimised PHA (pulse height analysis) setting in signal processing, instead of normal integral mode, which completely eliminated the second‐order MgKβ line. Second, the overlap of the first‐order FeLα on FKα peak, which cannot be filtered by modifying the PHA setting, was calibrated quantitatively using F‐free minerals and silicate glasses. Applying this two‐step method, F was determined in a number of reference glasses, as well as in glasses synthesised from powders of the rock reference materials AC‐E, GS‐N and DR‐N. Our data are consistent within error with F concentrations determined by other methods, demonstrating the reliability of this method.

Measurement of integral diffraction coefficients of crystals on beamline 4B7 of Beijing Synchrotron Radiation Facility

Integral diffraction coefficients of the crystal are the essential data of a crystal spectrometer which is extensively used to measure quantitative x-ray spectra of high temperature plasmas in kilo-electron-volt region. An experimental method has been developed to measure the integral diffraction coefficients of crystals on beamline 4B7 of Beijing Synchrotron Radiation Facility. The integral diffraction coefficients of several crystals including polyethylene terephthalate (PET), thallium acid phthalate (TlAP) and rubidium acid phthalate (RAP) crystals have been measured in the x-ray energy range 2100–5600 eV and compared with the calculations of the ‘Darwin Prins’ and the ‘Mosaic’ models. It is shown that the integral diffraction coefficients of these crystals are between the calculations of the ‘Darwin Prins’ and the ‘Mosaic’ models, but more close to the ‘Darwin Prins’ model calculations.

The influence of a magnetic field on the microhardness of K, Rb, Cs, NH4, and Tl acid phthalate crystals

The influence of a magnetic field on the microhardness of potassium acid phthalate has been studied for different magnetic inductions, exposure times, sample orientations in a magnetic field, and impurity compositions of the crystals. It was shown that the magnetic field effect is multiply repeated on the (010) face after relaxation. The influence of magnetic treatment on ammonium, rubidium, thallium, and cesium acid phthalate crystals is analyzed. The reasons for the observed changes in the crystal microhardness in the magnetic field are discussed.

Subpicosecond X-ray diffraction study of laser-induced disorder dynamics above the damage threshold of organic solids

Ultrafast disordering in Langmuir–Blodgett (LB) films and TlAP (thallium acid phthalate) crystals has been investigated by optical-pump–X-ray-probe experiments using intense femtosecond laser pulses. A laser-produced plasma X-ray source at 7.12 Å wavelength is used to study atomic dynamics by subpicosecond time-resolved X-ray diffraction. It is found that a drop of the X-ray diffracted intensity appears with time constants from below 600 fs up to a few tens of picoseconds in LB films optically excited at laser fluxes from 1.8 to 27 J cm−2. This loss in the diffracted intensity is understood as a displacement of the diffracting atoms by ∼8 Å from their equilibrium position. The response of the TlAP crystal was significantly slower. The relation to the atomic structure of the materials is discussed.

Wide-band, high-resolution soft x-ray spectrometer for the Electron Beam Ion Trap

We have constructed two wide-band, high-resolution vacuum flat crystal spectrometers and implemented them on the Electron Beam Ion Trap located at the Lawrence Livermore National Laboratory. Working in unison, these spectrometers can measure an x-ray bandwidth ⩽9 Å in the soft x-ray region below 21 Å. In order to achieve this large bandwidth each spectrometer houses either two 125 mm × 13 mm × 2 mm RAP (rubidium acid phthalate, 2d=26.121 Å), two 114 mm × 13 mm × 2 mm TlAP (thallium acid phthalate, 2d=25.75 Å) crystals, or some combination thereof, for dispersion and two position sensitive proportional counters for detection of x rays. The spectrometers are used to measure wavelengths and relative intensities of the L-shell line emission from Fe XVII–XXIV for comparison with spectra obtained from astrophysical and laboratory plasmas. The wide wavelength coverage attainable by these spectrometers makes it possible to measure all the L-shell emission from a given iron ion species simultaneously.

Soft-x-ray imaging with toroidally curved thallium acid phthalate crystals in the water window

Two-dimensional imaging in the wavelength region of the water window (N Ly alpha) is demonstrated with a toroidally curved thallium acid phthalate crystal. Direct imaging of a plasma pinch line, as well as imaging of a mesh with plasma backlighting in which the same source is used, is shown. For verification, the results are compared with the results by other methods. An absolute intensity calibration of the images is demonstrated with theoretical data for the reflection properties of the crystal. This advance in two-dimensional imaging was possible owing to the recent progress in the precise bending of acid phthalate crystals to defined concave shapes of high quality (sphere, toroid). With these crystals, the two-dimensional imaging method is pushed to the wavelength of 2.66 nm, which is well inside the water window.

Solution growth of large section thallium acid phthalate single crystals by joining seed

Growth of large section thallium acid phthalate (TAP) single crystals by joining seed was investigated. Two crystal plates cleaved from the same piece of TAP crystal were joined, one plate along <110 > and one plate along < 1 1 0 > , so that their a , b and c orientations were consistent. One seed plate had an area of (001) face two times larger than that of the single original plate. Growth conditions were solution pH = 3.98, rate of decreasing temperature = 0.3-0.4°C/day and temperature range = 55–75°C. A large perfect crystal of 95 x 65 x 50 mm 3 in size was finally obtained. The X-ray diffraction characteristic parameters of TAP crystals grown by joining seed were measured; interplanar spacing 2d( 001) = 25.78 A ̊ diffraction peak coefficient P = 71%; full width at half maximum w = 38”; integral reflection coefficient R = 1.0 x 1.0 −5 arc sec. Meanwhile, the joining technique was applied, along <100 > and < 1 00 > , <010 > and <0 1 0 >, respectively, and with the (110) face and ( 1 1 0) face as the joining interface, to the (001) plates cleaved from the same piece of the TAP crystal. The results are discussed briefly.

Effects of Dislocations on Growth Habit in Crystal of Thallium Acid Phthalate

The spiral and ordinary dislocations both running nearly perpendicular to the (001) growth surface of thallium acid phthalate, were revealed and identified by x-ray topography. They play an unexpectedly important role on that face by providing the self-perpetuating step sources so as to accelerate its growth rate or even to change its crystal morphology.

BORRMANN IMAGE OF DISLOCATION IN THE CRYSTAL OF THALLIUM ACID PHTHALATE

The crystal of thallium acid phthalate (TAP) is a newly developed X-rays analyzing ele-ment with higher diffraction power. The Bormann image of the spiral dislocations has been observed and studied by means of X-ray topography. It is shown that the image contrast with fine structure nearly in the core of dislocation is decreasing not only with decreasing the crystal thickness, but also with decreasing the Borrmann coefficient s so greatly as to blur or even to make the fine contrast information loss completely when the images are inversed from "white" to "black" in the contrast.

Chemical-shift analysis of O Kα by EPMA color-mapping method for BiSrCaCuO superconductive specimen

The chemical shifts of x-ray spectra are now frequently observed with EPMA (Electron Probe Microanalysis). The conventional method of chemical-shift analysis with EPMA is to compare the peak shapes and peak positions of standard spectra with those of unknown spectra. We reported that O-Kα peak shapes detected by using a TAP (Thallium acid phthalate) crystal reflect their crystal structures. Fig. 1 shows these O-Kα spectral peaks. In the present study, concerning the BiSrCaCuO superconductor made by the sintering method, it was observed that the O-Kα spectra of several kinds of phases reflected their crystal structures. Moreover, it is now possible to observe these chemical shifts of spectra by using the color mapping method in EPMA.

Analytical characteristics of a multilayer dispersion element (2d = 60 Å) in the determination of fluorine in minerals by electron microprobe

AbstractThe analytical characteristics of a W/Si multilayer dispersion element (MLDE) with a nominal 2d spacing of 60 Å are assessed and compared with those of a conventional thallium acid phthalate (TAP) crystal for the determination of fluorine in silicate and phosphate minerals by electron microprobe. Measured count rates for fluorine were found to be up to fourteen times higher using the MLDE compared with TAP giving improved detection limits of 0.02 to 0.08 wt. % F (six sigma, 100s count time) compared with equivalent data of 0.06 to 0.12 wt. % F by TAP. At equivalent spectrometer angles, peak widths by MLDE were broader by a factor of 2 to 3. However, an important advantage of MLDE was found to be the absence of multiple order diffractions higher than the second order. In consequence, the troublesome third order P-Kα line interference on the F-Kα line, normally encountered in the analysis of apatites, is absent in determinations made using the MLDE. Conversely small interferences on the F-Kα line were detected from the first-order Lα line of Fe and second-order Lα line of Mg. X-ray data and spectra of selected minerals are presented to demonstrate these interferences. Detection limits for elements that can also be determined using the MLDE were 0.07 to 0.15 wt. % oxygen and 0.34 wt. % carbon.

New organic crystals as x‐ray monochromators: Triphenylbenzene and thalliúm tartrate

AbstractThe usefulness of analysing crystals for x‐ray spectrometry is governed, to a large extent, by their angular dispersion and reflection efficiency, but other features such as crystal fluorescence must also be taken into account. Experimental results are presented that illustrate the performances of two organic crystals: (i) triphenylbenzene, which constitutes an attractive alternative to ammonium dihydrogen phosphate for the determination of magnesium in cements and other calcium‐containing matrices, and (ii) thallium tartrate, which may be recommended for the determination of sodium and possibly magnesium instead of the widely used thallium acid phthalate.

Quantitative X-ray fluorescence analysis of boron in thin films of borophosphosilicate glasses

X-ray fluorescence analysis of boron is complicated by the low atomic number and the low K shell energy of boron, and the effects of these on excitation, fluorescence yield, absorption and energy analysis. At present, acceptable energy resolution and sensitivity with small equipment dimensions and the capability of processing high photon counting rates can only be met by wavelength-dispersive energy analysis using synthetic multilayers as the diffraction device. These multilayers, compared with thallium acid phthalate and lead stearate, show a far increased reflectivity. They differ, however, from common analyser crystals in the marked appearance of higher order Bragg reflections. The analysis of boron in a matrix containing oxygen, for instance borophosphosilicate glass, is hampered by the overlap of B Kα in the first order and O Kα in the third order. It has been demonstrated that undesirable higher order Bragg reflections can be extinguished by employing multilayer structures with an appropriate thickness ratio of the layer pair. Thereby, it is possible to determine the mass content of boron in borophosphosilicate glass with an accuracy better than 0.2 wt.% B in a measuring time of 5 min.

Layered Synthetic Microstructures in Sequential and Simultaneous X-Ray Spectrometry

SummaryFor many years Layered Synthetic Microstructures (LSM's) have been used successfully as dispersive devices. The commercial variety introduced in 1984 offered significantly greater stability and diffracted intensity characteristics over Thallium Acid Phthalate (TAP) crystals. These devices offer superior sensitivity for fluorine, sodium and magnesium in all but a few applications where resolution is very critical. Subsequently, a variety of these devices have been optimised for analysis of the lower atomic number elements.Recently, several industrial applications have required the development of LSM's with 2d spacings optimised to enable quantitative analysis of oxygen, nitrogen, carbon and even boron. In these applications, the large incremental difference in characteristic wavelength per atomic number step limits the dynamic range of elements over which the LSM can be optimised. These considerations are discussed as they relate to routine analyses of very low atomic number elements by sequential Wavelength Dispersive Spectrometry (WDS).Newly developed fabrication techniques are used to produce curved LSM's for use with the focusing optics of simultaneous WDS. Application of these curved devices for the analysis of Mg in steel, Na in slags and F in glass will be discussed.Finally, an application which requires the analysis of thin films on semiconductor devices will be described. In this method, characteristic K-spectra and L-spectra of low and high atomic number elements, respectively, are selected for optimum sensitivity to the surface composition.

X-ray spectral line coincidences between fluorine K- and transition-metal L-series lines

X-ray spectroscopy was performed in the 12–15-Å region, recording L-series lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Cr, Mn, Fe, and Ni L spectra, and F viii and F ix K-shell lines. Wavelengths were determined to accuracies of 1–3 mÅ and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions, using 1.05- and 0.527-μm laser excitation with the KMS CHROMA laser. Laser intensity varied from 1.2–2.5×1014 W/cm2 in 200-ps pulses. Three groups of x-ray spectra were collected with highly dispersive x-ray crystals at wave bands centered at 12.643, 13.781, and 14.458 Å, corresponding to H- and He-like lines from fluorine. Two specially designed flat crystal spectrographs employing camera shutters were used with pairs of beryl and thallium acid phthalate (TAP) crystals. The spectra from potential lasant and pump candidates could be recorded on the same spectrogram to aid in identifying x-ray line coincidences. In cases where wavelengths were measured in both the 1.05- and 0.527-μm laser work, agreement within 1–3 mÅ was obtained for the L-series x-ray lines. Within this accuracy range, some five L-series x-ray lines, mostly 2p-3d transitions from the metals Cr, Mn, and Ni, had wavelength values coincident with K-series lines in fluorine.

A high-resolution x-ray diagnostic technique using simultaneous diffraction from several planes of acid phthalate crystals

An x-ray diagnostic tool was developed for acquiring and interpreting high-resolution spectra for hot-plasma emission from selected elements. A convex, curved potassium acid phthalate (KAP) crystal was used to collect spectral data from an exploded-A1-wire plasma over a wide exposure latitude with the 001, 002, and the 013 planes simultaneously diffracting. The curved-crystal diffraction efficiencies were calculated for these three planes in KAP and evaluated with x-ray line intensities derived from the experimental A1 data. The crystal efficiencies were also computed for two other commonly used acid phthalate crystals rubidium acid phthalate (RAP) and thallium acid phthalate (TAP), to compare with KAP crystals. The calculated efficiencies for the first-order diffraction in KAP, RAP, and TAP agreed with available experimental data.

Comparison of crystals for oxygen analysis

AbstractA comparison is made between five acid phthalates and clinochlore as analyzer crystals for oxygen Kα emission. Thallium acid phthalate (TAP) is shown to be superior for quantitative analysis because it has high reflectivity, relatively smaller corrections to reflectivity for anomalous dispersion, relatively low high order reflectivities and relatively low fluorescence background. The interplanar 2d spacing for TAP is 25.7626 ± 0.001 Å and its coefficent of thermal expansion α is 32.7 ± 1 K−1. At the oxygen Kα position its effective 2d spacing is 25.724 Å and the mean reflection coefficient is 2.8 × 10−4 rad. For analysis of chemical state, where higher resolution is often desired to distinguish band shapes and satellites, rubidium acid phthalate (RAP) is the best choice. It has α = 37.0±3 K−1, an effective 2d spacing of 26.083 Å and a mean reflection coefficient of 8.2 × 10−5 rad.

The evaluation of the thallium acid phthalate crystal for X‐ray fluorescene spectrometry

AbstractThe Thallium Acid Phthalate (TIAP) analysing crystal is compared with KAP, RBAP and pentaerythritol (PE) crystal for the determination of light elements. Peak and background intensities are compared for various crystal‐collimator combinations. It is shown that TIAP is a very useful crystal to cover the range of elements F to Si.