Charge-coupled Device Spectrometer Research Articles

Miniaturized dielectric barrier discharge-molecular emission spectrometer for determination of total sulfur dioxide in food

SO2 is a type of additive widely used in the food processing industry as preservative and anti-browning, bleaching, or effective antibacterial agent. However, the SO2 residue can have adverse effects on human health. In this work, a low-temperature microplasma generated by dielectric barrier discharge was used for the direct, in situ excitation of the molecular emission of SO2 in food samples. The food samples were acidified and heated to release SO2 and a miniaturized charge-coupled device spectrometer recorded the characteristic emission line at 301.9 nm. The linear correlation coefficient of the method was greater than 0.99 in the range of 10 to 100 mg L−1. Moreover, the limit of detection was 0.01 mg L−1, with recoveries between 72% and 108% and relative standard deviations of 1.5%–7.6%. The method is simple, accurate, low-cost, involves miniaturized and compact equipment and is suitable for the determination of total SO2 in food samples.

Application of Charge Coupled Device Spectrometer in Oil-Bearing Rock Detection

Application of Charge Coupled Device Spectrometer in Oil-Bearing Rock Detection

Accurate wavelength calibration method for compact CCD spectrometer.

Wavelength calibration is an important step in charge-coupled device (CCD) spectrometers. In this paper, an accurate calibration method is proposed. A model of a line profile spectrum is built at the beginning, followed by noise reduction, bandwidth correction, and automatic peak-seeking treatment. Experimental tests are conducted on the USB4000 spectrometer with a mercury-argon calibration light source. Compared with the traditional method, the results show that this wavelength calibration procedure obtains higher accuracy and the deviations are within 0.1 nm.

Fast-type high-accuracy universal polarimeter using charge-coupled device spectrometer

A fast, high-accuracy universal polarimeter was developed using a charge-coupled device (CCD) spectrometer (CCD-HAUP), to carry out simultaneous optical anisotropic (linear birefringence, LB; linear dichroism, LD) and chiroptical (circular birefringence, CB; circular dichroism, CD) measurements on single crystals without any pretreatment, in the visible region between 400–680 nm. The principle of the HAUP method is to measure the intensities of emergent light passing through a polarizer, a crystal sample, and then an analyzer, as the azimuth angles of the polarizer and analyzer are independently altered. The CCD-HAUP has the unique feature that white transmitted light intensity can be measured using a CCD spectrometer, compared with the generalized HAUP (G-HAUP) system in which monochromatic transmitted light is measured using a photomultiplier. The CCD-HAUP measurements across the entire wavelength region are completed within the G-HAUP measurement time for a single wavelength. The CCD-HAUP drastically reduces the measurement time for a dataset to only 1.5 h, from the 24 h required for the G-HAUP system. LB, LD, CB, and CD measurements of single crystals of α-quartz and enantiomeric photomechanical salicylidenephenylethylamines before, during, and after ultraviolet light irradiation show results comparable to those obtained using the G-HAUP system. The newly developed system is very effective for samples susceptible to degradation induced by external stimuli, such as light and heat.

Fiber-MZI-based FBG sensor interrogation: comparative study with a CCD spectrometer.

We present an experimental comparative study of the two most commonly used fiber Bragg grating (FBG) sensor interrogation techniques: a charge-coupled device (CCD) spectrometer and a fiber Mach-Zehnder interferometer (F-MZI). Although the interferometric interrogation technique is historically known to offer the highest sensitivity measurements, very little information exists regarding how it compares with the current commercially available spectral-characteristics-based interrogation systems. It is experimentally established here that the performance of a modern-day CCD spectrometer interrogator is very close to a F-MZI interrogator with the capability of measuring Bragg wavelength shifts with sub-picometer-level accuracy. The results presented in this research study can further be used as a guideline for choosing between the two FBG sensor interrogator types for small-amplitude dynamic perturbation measurements down to nano-level strain.

Wavelength dependence of the ablation characteristics of Cu (In, Ga) Se2 solar cell films and its effects on laser induced breakdown spectroscopy analysis

As a novel method for fast depth profile analysis of Cu (In, Ga) Se2 (CIGS) thin film solar cell, laser induced breakdown spectroscopy (LIBS) is introduced, and the effects of laser wavelength on depth resolution are investigated. From LIBS analysis of a commercial CIGS solar cell using an ultraviolet (λ = 266 nm) and a visible (λ = 532 nm) nanosecond Nd: YAG lasers and an intensified charge-coupled device spectrometer, it is shown that the use of a shorter wavelength laser does not guarantee an enhancement of depth resolution. Although the averaged ablation depth per pulse was smaller for the ultraviolet laser, the craters produced by the visible laser was much smoother and more uniform, demonstrating that depth resolution depends not only on laser wavelength but also strongly on the ablation mechanisms.

Fast temperature spectrometer for samples under extreme conditions.

We have developed a multi-wavelength Fast Temperature Readout (FasTeR) spectrometer to capture a sample's transient temperature fluctuations, and reduce uncertainties in melting temperature determination. Without sacrificing accuracy, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range, and a well-constrained focus. Complimenting a charge-coupled device spectrometer, FasTeR consists of an array of photomultiplier tubes and optical dichroic filters. The temperatures determined by FasTeR outside of the vicinity of melting are, generally, in good agreement with results from the charge-coupled device spectrometer. Near melting, FasTeR is capable of capturing transient temperature fluctuations, at least on the order of 300 K/s. A software tool, SIMFaster, is described and has been developed to simulate FasTeR and assess design configurations. FasTeR is especially suitable for temperature determinations that utilize ultra-fast techniques under extreme conditions. Working in parallel with the laser-heated diamond-anvil cell, synchrotron Mössbauer spectroscopy, and X-ray diffraction, we have applied the FasTeR spectrometer to measure the melting temperature of (57)Fe0.9Ni0.1 at high pressure.

Quantitative analysis with advanced compensated polarized light microscopy on wavelength dependence of linear birefringence of single crystals causing arthritis

To improve our ability to identify single crystals causing arthritis, we have developed a practical measurement system of polarized light microscopy called advanced compensated polarized light microscopy (A-CPLM). The A-CPLM system is constructed by employing a conventional phase retardation plate, an optical fibre and a charge-coupled device spectrometer in a polarized light microscope. We applied the A-CPLM system to measure linear birefringence (LB) in the visible region, which is an optical anisotropic property, for tiny single crystals causing arthritis, i.e. monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD). The A-CPLM system performance was evaluated by comparing the obtained experimental data using the A-CPLM system with (i) literature data for a standard sample, MgF2, and (ii) experimental data obtained using an established optical method, high-accuracy universal polarimeter, for the MSUM. The A-CPLM system was found to be applicable for measuring the LB spectra of the single crystals of MSUM and CPPD, which cause arthritis, in the visible regions. We quantitatively reveal the large difference in LB between MSUM and CPPD crystals. These results demonstrate the usefulness of the A-CPLM system for distinguishing the crystals causing arthritis.

Depth profiling analysis of CuIn_1-xGa_xSe_2 absorber layer by laser induced breakdown spectroscopy in atmospheric conditions

This work reports the capability of depth profile analysis of thin CuIn1-xGa(x)Se2 (CIGS) absorber layer (1.89 μm) with a sub-hundred nanometer resolution by laser induced breakdown spectroscopy (LIBS). The LIBS analysis was carried out with a commercial CIGS solar cell on flexible substrate by using a pulsed Nd:YAG laser (λ = 532 nm, τ = 5 ns, top-hat profile) and an intensified charge-coupled device spectrometer in atmospheric conditions. The measured LIBS elemental profiles across the CIGS layer agreed closely to those measured by secondary ion mass spectrometry. The resolution of depth profile analysis was about 88 nm. Owing to the short measurement time of LIBS and the capability of in-air measurement, it is expected that LIBS can be applied for in situ analysis of elemental composition and their distribution across the film thickness during development and manufacturing of CIGS solar cells.

Development of micro-optics for high-resolution IL spectroscopy with a proton microbeam probe

Confocal optics for ion luminescence (IL) was developed for the precise analysis of the chemical composition of microscopic targets with an external proton microbeam probe. Anti-reflection-coated confocal micro-lens optics with an effective focus area of approximately 800×800μm was installed on the microbeam line of a single-ended accelerator. Chromatic aberrations of the confocal optics were examined at wavelengths of 300–900nm. An electrically-cooled back-thinned charge coupled device spectrometer with a wavelength resolution of 0.5nm was used for the microscopic spectroscopy and IL imaging of microscopic mineral targets. Simultaneous microscopic IL and micro-PIXE analysis were performed using an external 3MeV H+ microbeam with a current of less than 100pA. A spectral resolution of 3nm was achieved for a single IL peak which corresponded to Cr3+ impurities in a single-crystal of aluminum oxide. The use of IL spectroscopy and imaging for aerosol targets revealed microscopic distributions of the chemical and elemental composition in the atmosphere.

Characterization of sliding spark plasma source for direct trace spectronalysis

The sliding spark plasma – which is produced via ablation of a dielectric material enforced between a pair of electrodes by a pulsed high-voltage discharge propagating along the dielectric surface – has immense potential as a simple but novel spectroscopic source for direct in situ quantitative analysis of non-conducting samples, a ubiquitous theme in material characterization. The plasma-excited optical spectrum spans a broad spectral range Vacuum Ultra Violet-Near Infra Red (VUV-NIR) and carries the atomic and molecular signatures of the base matrix chemical composition. Since the analytical figures of merit for quantitative spectroanalysis are a function of the spark source and dielectric matrix ablation characteristics, we systematically studied the sliding spark plasma source, utilizing a charge-coupled device spectrometer with blazed holographic grating in order to find the combination of parameters that can tailor the source for trace spectroanalysis of dielectrics in air and atmospheric pressure. It was observed that in the UV–vis spectral range a unique set of sample matrix conditions, besides spark source parameters, exists for enhanced trace analyte spectral emission with low signal-to-noise ratios and where trace spectrochemical analysis of dielectrics depends multivariately on spark scan frequency, electrode geometry, plasma discharge current, spark source inductance, initial rate of applied voltage, mode of sample ablation, and specific capacitance of the dielectric surface.

Iodine excitation in a dielectric barrier discharge micro-plasma and its determination by optical emission spectrometry

A low temperature micro-plasma generated in a dielectric barrier discharge (DBD) was used as a radiation source for the excitation of iodine and its determination by vapor generation-optical emission spectrometry. A piece of ceramic tube served as an excitation chamber to provide a small gas path for introducing a helium stream to generate a DBD micro-plasma by using a neon power supply. Iodine was on-line vaporized by reaction of iodide in sample solution (or iodate pre-reduced to iodide by ascorbic acid) with H(2)O(2). The vapor was subsequently separated and transferred into the DBD excitation chamber by a helium stream for performing optical emission and detection at a 905 nm emission line. The emission spectra were measured with a QE65000 charge-coupled device spectrometer. A few important issues governing the performance of the entire system, e.g., selection of the analytical emission line, elimination of the DBD micro-plasma background variation and optimization of the experimental parameters, were investigated. With a sampling volume of 1.0 mL, a linear range of 0.1-10.0 mg L(-1) was obtained along with a detection limit of 0.03 mg L(-1). A precision of 2.1% RSD was achieved at the concentration level of 2 mg L(-1) iodine. The present system was applied in the determination of trace iodine in real samples, i.e., GBW10023 laver, table salt and cydiodine buccal tablets, giving rise to satisfactory results.

Sequential monitoring of elemental mercury in stack gas by dielectric barrier discharge micro-plasma emission spectrometry

A simple device was constructed for the on-site sequential monitoring of emitted elemental mercury (Hg0) in coal-fired stack gas. The device integrates on-line gold amalgam preconcentration, external thermal desorption and cold excitation in an enclosed atmospheric-pressure dielectric-barrier discharge (DBD) micro-plasma chamber. The emission was monitored by using a charge coupled device spectrometer. The Hg0 emission at 253.7 nm was well separated from the emission spectra of the Ar-DBD-plasma which eliminates the spectral interferences of ambient air and gaseous inorganic small molecular pollutants in the stack gas, e.g., NOx, SO2, H2S and HCl. Quantification was based on first derivative spectra. Among the three mercury species, Hg0 is efficiently and selectively trapped on the gold amalgam at <220 °C, the threshold temperature for thermal desorption of the trapped Hg0 is ca. 420 °C above which the gold amalgam releases the enriched Hg0 rapidly and gives rise to a high concentration of Hg0 in the flowing Ar stream in a very short period of time which significantly improves the detection sensitivity. A linear calibration graph was achieved within 8–256 ng (the mass of enriched Hg0 on the gold trapping micro-column) with a detection limit of 2.3 ng and an RSD of 4.0% at 32 ng. A spiking recovery of 96.1% was achieved at a spiking mass level of 50 ng Hg0. For real sample analysis (stack gas from a honeycomb briquette stove), a calibration range of 2.7–60.8 ppt was achieved after 5 min preconcentration with a 0.5 L min−1 sampling flow rate.

Development of a miniature analytical system in a lab-on-valve for determination of trace copper by bead injection spectroscopy

A miniature analytical system based on a lab-on-valve platform is developed for trace metal analysis by bead injection spectroscopy. A multipurpose flow cell integrated into a lab-on-valve is furnished with two pieces of fiber optics to communicate with light source and charge coupled device (CCD) spectrometer, respectively, in order to monitor real-time absorbance of the samples. Micro-beads loaded with chromogenic reagent are packed into the multipurpose flow cell to form a renewable microcolumn for solid phase extraction by bead injection. When the sample solution flows through the microcolumn, the target analyte will be captured on the surface of beads and detected directly by the CCD spectrometer without elution. The beads are automatically discarded from the multipurpose flow cell after each analytical cycle. This analytical system was employed to determine trace copper by loading of a chromogenic reagent 2-carboxy-2′-hydroxy-5′-sulfoformazylbenzene (zincon) on the beads of an anion exchanger (Sephadex QAE A-25). With a sample volume of 2.5mL, a detection limit of 3μgL−1 and a linear range of 10–100μgL−1 were obtained for copper, along with a RSD value of 2.5% (at the 50μgL−1 level). The accuracy and practical applicability of the proposed system were validated by analysing certified reference materials, i.e., GBW10010, GBW09101, GBW08608, and further demonstrated by spiking recovery of copper in a water sample.

DESIGN OF A PORTABLE ELECTROTHERMAL VAPORIZATION FLAME ATOMIC EMISSION SPECTROMETRY DEVICE FOR FIELD ANALYSIS

A nontraditional, portable flame atomic emission spectrometry (FAES) device has been constructed using a welding industry metal cutting torch as the flame source with a tungsten coil electrothermal vaporization device for sample introduction. Twenty-microliter sample aliquots were pipetted onto a commercially available tungsten filament, and a home-written Visual Basic program was used to automatically dry and atomize the sample. The sample was then transported into the heart of the air-acetylene flame, where it was excited, and the resulting emission signal was focused onto the entrance of a miniature charge coupled device spectrometer. Figures of merit were determined for five alkaline and alkali earth metals of biological and environmental significance. Limits of detection were, on average, 100 times lower than those for traditional flame emission spectrometers. The capabilities of this portable device make it an ideal tool for biological field analysis, particularly in areas where traditional laboratories are inaccessible.

Dielectric Barrier Discharge Molecular Emission Spectrometer as Multichannel GC Detector for Halohydrocarbons

A novel microplasma molecular emission spectrometer based on an atmospheric pressure dielectric barrier discharge (DBD) is described and further used as a promising multichannel GC detector for halohydrocarbons. The plasma is generated in a DBD device consisting of an outer electrode (1.2 mm in diameter) and an inner electrode (1.7 mm in diameter) within a small quartz tube (3.0 mm i.d. × 5.0 mm o.d. × 50 mm), wherein analyte molecules are excited by the microplasma to generate molecular emission. Therefore, the analytes are selectively and simultaneously detected with a portable charge-coupled device (CCD) via multichannel detection of their specific emission lines. The performance of this method was evaluated by separation and detection of a model mixture of chlorinated hydrocarbons (CHCl(3) and CCl(4)), brominated hydrocarbons (CH(2)Br(2) and CH(2)BrCH(2)Br), and iodinated hydrocarbons (CH(3)I and (CH(3))(2)CHI) undergoing GC with the new detector. The completely resolved identification of the tested compounds was achieved by taking advantages of both chromatographic and spectral resolution. Under the optimized conditions with the CCD spectrometer set at 258, 292, and 342 nm channels for determination of chlorinated hydrocarbons, brominated hydrocarbons, and iodinated hydrocarbons, respectively, this detector with direct injection provided detection limits of 0.07, 0.06, 0.3, 0.04, 0.05, and 0.02 μg mL(-1) for CCl(4), CHCl(3), CH(2)Cl(2), CH(3)I, CH(3)CH(2)I, and (CH(3))(2)CHI, respectively.

Study on the chemiluminescence resonance energy transfer between luminol and fluorescent dyes using a linear CCD spectrometer

Chemiluminescence (CL) has been a useful tool for analytical applications. Fluorescein can be used to enhance CL emission of luminol. With three-dimensional (3D) dynamic CL spectrum obtained from a linear CCD (charge-coupled device) flow-injection CL spectrometer, the fluorescein enhanced CL analysis was studied. The enhanced process can be described with chemiluminescence resonance energy transfer (CRET) at certain fluorescein concentrations. In the process of CRET, fluorescein enlarges CL intensity but does not join the CL reaction. Compared with classic luminol–Co 2+ CL system, the fluorescein-enhanced system exhibits stronger CL signal with the linear range and detection limit for traces of Co 2+ unchanged.

A Compact Spectrophotometer Using Liquid Core Waveguide and Handheld Charge Coupled Device: For Green Method and Ultrasensitive Speciation Analysis of Cr(III) and Cr(VI)

ABSTRACT In this short letter, we report a compact spectrophotometer consisting of a liquid core waveguide as the optical cell and a handheld charge coupled device spectrometer as the detector. This instrumentation features portability, ultrahigh sensitivity, simultaneous multicomponent detection, and minimal analyte solution. Its ultrahigh sensitivity permits the measurement of Cr(III) without coloration with any reagents. Therefore, a simple, fast, cost-effective, and green analytical method was developed for the ultrasensitive and simultaneous speciation analysis of Cr(III) and Cr(VI) in water samples, with the limits of detection down to the ppb level.

Design and development of an automated flow injection instrument for the determination of arsenic species in natural waters.

The design and development of an automated flow injection instrument for the determination of arsenite [As(III)] and arsenate [As(V)] in natural waters is described. The instrument incorporates solenoid activated self-priming micropumps and electronic switching valves for controlling the fluidics of the system and a miniature charge-coupled device spectrometer operating in a graphical programming environment. The limits of detection were found to be 0.79 and 0.98 microM for As(III) and As(V), respectively, with linear range of 1-50 microM. Spiked ultrapure water samples were analyzed and recoveries were found to be 97%-101% for As(III) and 95%-99% for As(V), respectively. Future directions in terms of automation, optimization, and field deployment are discussed.

Characterization of a picosecond laser generated 4.5keV TiK-alpha source for pulsed radiography

K α radiation generated by interaction of an ultrashort (1ps) laser with thin (25μm) Ti foils at high intensity (2×1016W∕cm2) is analyzed using data from a spherical Bragg crystal imager and a single hit charge-coupled device spectrometer together with Monte Carlo simulations of Kα brightness. Laser to Kα and electron conversion efficiencies have been determined. We have also measured an effective crystal reflectivity of 3.75±2%. Comparison of imager data with data from the relatively broadband single hit spectrometer has revealed a reduction in crystal collection efficiency for high Kα yield. This is attributed to a shift in the K-shell spectrum due to Ti ionization.