Spectrographic Detection Research Articles

Planar Photonic Chips with Tailored Dispersion Relations for High-Efficiency Spectrographic Detection

Planar Photonic Chips with Tailored Dispersion Relations for High-Efficiency Spectrographic Detection

Automation of ISP 51 Spectrograph by NI LabVIEW and digital camera

In this project, the ISP 51 (Inductively Coupled Plasma) automation was implemented to perform digital calculations. For this, a digital camera was placed in the spectrograph detection area, and all the images obtained were processed using the LabVIEW software environment.

Using a simple spectrophotometer to analyze cypress hydrolat composition.

The Pure Dew (Cypress Hydrolat), which could be extracted from the waste material after the extracting essential oil from Taiwan cypress, has a good bactericidal effect. However, due to the high cost on quality control and concentration measurement of the Pure Dew, its application was restricted. This research tries to find suitable spectral frequencies through which the absorbance detected by the spectrometer could be used as the index of the pure dew concentration. This study used Gas Chromatography-Mass Spectrophotometer (GC-MS) to analyze the composition of Taiwan cypress hydrolat. After obtaining the composition, the raw liquor of cypress hydrolat was diluted to 100, 50, 25 and 0% v/v with pure water. The test samples were then tested by a simple spectrophotometer. After the spectrographic detection of absorbance using a simple spectrophotometer, it is confirmed that the spectrum of wavelength between 205-350 nm is the most representative. The absorptance and the pure dew concentration was roughly in linear relation which suggested that a simple spectrophotometer can be used to develop a low-cost and high.

SALT HRS Discovery of the Binary Nucleus of the Etched Hourglass Nebula MyCn 18

AbstractThe shaping of various morphological features of planetary nebulae is increasingly linked to the role of binary central stars. Identifying a binary within a planetary nebula offers a powerful tool with which to directly investigate the formation mechanisms behind these features. The Etched Hourglass Nebula, MyCn 18, is the archetype for several binary-linked morphological features, yet it has no identified binary nucleus. It has the fastest jets seen in a planetary nebula of 630 km s−1, a central star position offset from the nebula centre, and a bipolar nebula with a very narrow waist. Here we report on the Southern African Large Telescope High Resolution Spectrograph detection of radial velocity variability in the nucleus of MyCn 18 with an orbital period of 18.15 ± 0.04 d and a semi-amplitude of 11.0 ± 0.3 km s−1. Adopting an orbital inclination of 38 ± 5° and a primary mass of 0.6 ± 0.1 M⊙ yields a secondary mass of 0.19 ± 0.05 M⊙ corresponding to an M5V companion. The detached nature of the binary rules out a classical nova as the origin of the jets and the offset central star as hypothesised in the literature. Furthermore, scenarios that produce the offset central star during the AGB and that form narrow waist bipolar nebulae result in orbital separations 80–800 times larger than observed in MyCn 18. The inner hourglass and jets may have formed from part of the common envelope ejecta that remained bound to the binary system in a circumbinary disk, whereas the offset central star position may best be explained by proper motion. Detailed simulations of MyCn 18 are encouraged that are compatible with the binary nucleus to further investigate its complex formation history.

Comparison between Two Detection Systems for Fiber-Optic Chemical Sensor Applications

Two optical detection system designs are compared for fiber-optic chemical sensor applications. A single grating spectrograph with fiber-optic input and photodiodes at three different wavelengths is compared to 1x3 fiber-optic splitters and photodiode detectors with integrated interference filters. The splitters are used to direct the optical power to the filter photodiodes. Three types of 1x3 commercially available splitters were tested: a 400 microm fused glass fiber-optic coupler, a 1000 microm fused plastic fiber-optic coupler, and a 1000 microm glass fiber-optic bundle. This study finds that the fiber-splitter-based detection systems have similar stray light, signal-to-noise ratio, and long-term absorbance stability compared to the spectrograph detection system with a modest improvement in spectral resolution (from approximately 12 nm to approximately 6 nm). It is also much smaller in size and lower in cost. Applications of the two systems in a colorimetric CO2 partial pressure sensor are compared and similar accuracy and precision are achieved.

PAH metabolites in bile, cytochrome P4501A and DNA adducts as environmental risk parameters for chronic oil exposure: a laboratory experiment with Atlantic cod

In order to perform environmental risk assessments with regard to oil contamination in the sea, it is important to obtain knowledge about threshold levels for possible adverse effects in marine organisms. With this objective in mind, selected biomarkers were studied in Atlantic cod ( Gadus morhua) chronically exposed to mechanically dispersed crude oil. The fish were exposed for 30 days in a continuous flow system to nominal concentrations of 0.06, 0.25 and 1 ppm North Sea crude oil. Fish were sampled five times during the exposure period. In addition, the 1 ppm group and the control group were sampled 1 week after the end of exposure. Polyaromatic hydrocarbon (PAH) concentrations in the seawater were analysed regularly by direct fluorescence and, at one occasion, by gas chromatography with mass spectrographic detection (GC/MS) measurements. Liver samples were analysed for parent PAH levels by means of GC/MS measurements, and PAH metabolites in bile were analysed by means of fixed wavelength fluorescence. Cytochrome P450 induction in liver was estimated by ethoxyresorufin- O-deethylase (EROD) activity, and hepatic DNA adducts were analysed by the 32P-postlabelling assay. The parent PAH concentrations in liver showed peak levels 3 days after the start of exposure, followed by a reduction towards the end of the experiment. In contrast, the PAH metabolites in bile and EROD activity showed generally increasing levels throughout the whole exposure period, indicating an increased biotransformation efficiency. The level of DNA adducts in the 1 ppm group showed a stable increase during the entire exposure period. Only a slight, non-significant decrease in DNA adduct levels was observed after 7 days of recovery in clean water. Exposure-dependent responses were observed for all three biomarkers. The lowest nominal concentration of dispersed oil in water, 0.06 ppm, corresponded to a measured total PAH concentration in the water of 0.3 ppb. Atlantic cod exposed to this concentration showed increased levels of PAH metabolites in bile and a slight induction of CYP1A, as well as formation of DNA adducts when compared with control fish. Particularly noteworthy is the detection of DNA adducts at such a low exposure concentration of oil in water, which, to our knowledge, is a novel finding. These dose–response data may serve as useful contributions when assessing environmental risk with regard to marine oil pollution.

Flat and curved crystal spectrography for mammographic X-ray sources.

The demand for improved spectral understanding of mammographic X-ray sources and non-invasive voltage calibration of such sources has led to research into applications using curved crystal spectroscopy. Recent developments and the promise of improved precision and control are described. Analytical equations are presented to indicate effects of errors and alignment problems in the flat and curved crystal systems. These are appropriate for all detection systems. Application to and testing of spectrographic detection (using standard X-ray film) is presented. Suitable arrangements exist which can be used to measure X-ray tube voltages well below 1 kV precision in the operating range of 20-35 kV.

Conditional-sampling spectrograph detection system for fluorescence measurements of individual airborne biological particles

We report the design and operation of a prototype conditional-sampling spectrograph detection system that can record the fluorescence spectra of individual, micrometer-sized aerosols as they traverse an intense 488-nm intracavity laser beam. The instrument's image-intensified CCD detector is gated by elastic scattering or by undispersed fluorescence from particles that enter the spectrograph's field of view. It records spectra only from particles with preselected scattering-fluorescence levels (a fiber-optic-photomultiplier subsystem provides the gating signal). This conditional-sampling procedure reduces data-handling rates and increases the signal-to-noise ratio by restricting the system's exposures to brief periods when aerosols traverse the beam. We demonstrate these advantages by reliably capturing spectra from individual fluorescent microspheres dispersed in an airstream. The conditional-sampling procedure also permits some discrimination among different types of particles, so that spectra may be recorded from the few interesting particles present in a cloud of background aerosol. We demonstrate such discrimination by measuring spectra from selected fluorescent microspheres in a mixture of two types of microspheres, and from bacterial spores in a mixture of spores and nonfluorescent kaolin particles.

Graphite furnace for alternative combination with d.c. arc or inductively coupled plasma. Introduction and analysis of solid samples

A graphite furnace and d.c. arc combined source with the use of halogenating atmosphere in the furnace is described. The construction makes possible the introduction and analysis of both liquid and solid samples at minimum risk of contamination. Spectrographic detection resulted in background equivalent mass values below 10 ng for 22 from 36 elements applied in solution (Ar + CCl4 atmosphere and NaCl matrix). The intensity-time profiles indicated high rates of distillation of the impurities (including B, Cr, Hf, Mo, Ti, V, W and Zr) from silicon carbide and silicon nitride samples in the first 40 s of heating under chlorination (CCl4 vapour). Two versions of the exit part of the furnace are described for coupling to an ICP source; one of them has been used for the determination of titanium in alumina (spectrometric detection). Standardization with solution standards for solid sample analysis was unsuccessful. Based on the analytical curve obtained with variable amounts of solid standards (5–20 mg), a detection limit of 0.32 μg/g Ti was found for 20 mg alumina.

An assessment of prominent lines in inductively-coupled argon plasmas with special reference to spectrographic general survey analysis

About 600 prominent lines for inductively-coupled plasma-atomic emission spectrometry (ICP-AES) using an argon ICP were studied with the triple objective of (1) compiling a library of prominent lines for spectrographic general survey analysis in this laboratory, (2) comparing the detection limits and sensitivities of the lines with literature data, in particular those in the author's Line Coincidence Tables for ICP-AES [Pergamon Press, Oxford (1980)], and (3) providing a list of lines with “universal” sensitivities that can be generally used for semiquantitative analysis. A 50 MHz ICP operated under compromise conditions and spectrographic detection were used. The latter limited the wavelength region of the prominent lines covered to a range between 235 and 446 nm. For 598 lines listed in the Line Coincidence Tables (LCT) the paper presents the visually estimated detection limits and an assessment of band interferences in regions of ±0.05nm about the prominent lines. Similar data are presented for 88 computer predicted, supplementary prominent lines [Spectrochim. Acta 36B, 169 (1981)] for which the predictions came true. For the 383 prominent lines located between 252 and 446 nm densitometrically determined detection limits and sensitivities are given. The sensitivities were converted to a “universal scale”, independent of the spectral characteristics of the optics and the detector. The results of the visual and densitometric determinations are compared mutually and with the data given in the LCT, which are primarily based on the experimental work of Winge et al. [Appt. Specirosc. 33, 206 (1979)]; consequently the present paper also assesses the extent to which data for prominent lines can be transferred from the one ICP to the other, if both are operated under compromise conditions. The conversion of sensitivities on the “universal scale” to a scale applicable to a particular apparatus using the corresponding spectral distributions of the background intensity is discussed and illustrated with examples. The experimental results for 383 lines in the 252–446 nm region are shown to confirm the appropriateness of the data in the LCT for the great majority of the lines; 18 exceptions are specified and discussed. Similarly, for 29 lines below 252 nm or above 446 nm discrepancies with the LCT data are reported and discussed. The use of the complete set of results (including those on the supplementary prominent lines) as a basis for a library of prominent lines for spectrographic general survey analysis is explained. It is shown that in such a library, owing to the limitations that photographic detection imposes on the accessibility of the lower wavelength region, an order of prominence (“ranking”) has to be accepted which differs drastically from that in a “complete” library usable if no wavelength limitations are dictated by the spectroscopic apparatus. In this connection, the paper finally gives a brief outline of the operation of a computer software package used in this laboratory for line selection in general and for spectrographic survey analysis in particular.

Multichannel, direct-reading spectrograph attachment

An instrument is described which provides a multichannel direct-reading capability for photoelectric spectrographic detection. The important feature of the instrument is the ability of the user to select at will any combination of channels for position adjustment and to move these while preserving the optical integrity of the enclosure. Photomultipliers are used and the results of performance tests are described.

Thermal decomposition of potassium azide

Experimental studies of the thermal decomposition of single crystal and powder samples of KN3 in an ultrahigh vacuum environment are reported. Mass spectrographic detection was used to monitor the decomposition products and, from the temperature dependence of the N2 partial pressure, three regions of decomposition were found with associated activation energies of 1.0±0.1, 1.35±0.05, and 2.4±0.2 eV in order of increasing temperature. Azide radicals and potassium atoms were also detected in the decomposition products. The application of an electric field across the sample during decomposition was found to increase the decomposition rate for both signs of the voltage on the free surface of the crystal. The relaxation time for the pressure change associated with application of the field was found to be essentially the same as that for the decay of the induced ionic current to an equilibrium value. Models for the decomposition process are discussed.

Nanosecond pulse radiolysis effect studied spectrographically

Absorption spectra have been obtained for the benzene excimer and for solvated electrons in water, methanol and glycerol by a technique utilising a 3 nanosecond Čerenkov light flash as the internal source for spectrographic detection during pulse radiolysis.

Spectrographic Detection of Topographic Features on Mars

Observations of the martian carbon dioxide band at 1.05 microns made with a three-channel multislit spectrophotometer indicate gross height variations in the vicinity of Syrtis Major and surrounding desert regions. Syrtis Major appears to be very high with essentially no detectable carbon dioxide above it. The data appear to confirm local trends and, in magnitude at least, the large variations of height found in earlier radar observations. A one-to-one correlation of height with albedo is not evident in the results. Elevated areas are found in both desert and dark regions. In several regions dark areas are associated with relatively steep slopes.

Determination of lead and bismuth in molybdenum trioxide briquette

Determination methods of small amounts of lead and bismuth, contained in molybdenum trioxide briquette which is charged into the steelmaking furnace as a substitute for the ferromolybdenum, have been studied. Crashed and powdered sample are dissolved in aqua regia and organic matters present are decomposed completely by the addition of perchloric acid. After being cooled, the molybdenum acid anhydride deposited is dissolved either with ammonia water in the presence of tartric acid or with sodium hydroxide. Lead is extracted with dithizone-tetrachloride solution in advance from the solution of pH 10, containing tartarate and cyanide, and then, separated from bismuth by shaking with 0.05 N nitric acid. Finally, lead is extracted and measured as dithizonate in dithizone-benzene solution. Bismuth is extracted and determined photometrically as diethyldithio carbamate in the carbon tetrachloride solution, after being separated and concentrated according to the ferric hydroxide coprecipitation procedure. In the use of the spectrographic detection, conbined with the dithizonate extraction, it is confirmed that the samples do not contain any amount of thallium, which is interfered with the determination of lead and bismuth. Analytical results some commercial briquettes and ferromolybdenums are shown in Tables I and II.

Absorption Spectrum of Astatine*

A highly sensitive method of spectrographic detection of gases was used to detect the absorption of atomic astatine. Two lines were recorded whose wavelengths were 2244.01 and 2162.25 A. These lines were tentatively assigned to the transitions ²P320−⁴P52 and ²P320−⁴P32 between configurations 6p5 and 6p4 7s. The assignment of two resonant lines of polonium was confirmed.

Spectrographic detection of airborne silicon tetrafluoride

Experiments are described using one of two indirect methods which are possibly applicable to detection of traces of fluorine or fluorinated compounds in air. The fluorine must be converted to silicon tetrafluoride and the silicon is detected. The limit of detection of fluorine in silicon tetrafluoride is found to be 0·1 part per million.

Spectrographic detection of airborne fluorine

Abstract A flame light source capable of sampling a high-velocity air stream is described. An account is given of the application of this source to detection of airborne fluorine by formation and excitation of SrF molecules. At a flow rate of air of 100 l. min−1 and with 5 min exposure time for the recording of spectra, the limit of detection was 50 μg fluorine (present in air as CCl2F2) 1.−1, the SrF band head/background ratio then being 0·3.

Mass Spectrographic Detection of Impurities in Liquids

The mass spectrograph with the vacuum spark positive ion source distinguishes between bulk impurities in the electrodes and contaminants present on their surface. Surface contamination can be detected and identified when it is the equivalent of less than 0.01 monolayer in thickness. Impurities in liquids are studied by exposing an electrode to the liquid, thereby contaminating its surface. Two ways of contaminating an electrode surface are described: (a) electroplating of impurities onto the electrode, and (b) evaporation leaving residue on the electrode. Experiments with doped water demonstrate that impurities at a concentration of 10−9 atom fraction can be detected. Only about 10−10 g of impurity is needed for detection using the evaporation technique. Some applications are discussed.

The Spectrographic Detection of Selenium in the DC Arc Flame*

The Spectrographic Detection of Selenium in the DC Arc Flame*