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PubMed2004

Assessment of skeletal muscle perfusion by contrast medium first-pass magnetic resonance imaging: technical feasibility and preliminary experience in healthy volunteers.

PURPOSE: To probe the potential and pitfalls of contrast medium first-pass skeletal muscle perfusion imaging under reproducible stress conditions. MATERIALS AND METHODS: Magnetic resonance (MR) signal dynamics in calf muscle and lower-leg arteries of 20 healthy volunteers were analyzed under postarterial occlusion reactive hyperemia and concurrent contrast medium first pass, using a saturation recovery spoiled gradient-echo type sequence without heartbeat synchronization. The signal vs. time curves were analyzed descriptively and by two-compartment deconvolution analysis. RESULTS: Highly significant changes in calf muscle signal dynamics in the hyperemic leg vs. those in the contralateral leg at rest were found in phenomenological and deconvolution analysis. Although a distortion of the arterial signal derived input function by inflow effects was found to cause large variations of the deconvolution results, the magnitude of the observed effects suggested a potential for immediate visual detection of areas with reduced tissue perfusion. CONCLUSION: The first-pass approach appeared promising for visual evaluation. However, a disentanglement of inflow and contrast medium-induced effects on arterial signal intensity was deemed a prerequisite for input function-based numerical assessment.

Adult↗
PubMed2005

Principles of cerebral perfusion imaging by bolus tracking.

The principles of cerebral perfusion imaging by the method of dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) (bolus tracking) are described. The MRI signals underlying DSC-MRI are discussed. Tracer kinetics procedures are defined to calculate images of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT). Two general categories of numerical procedures are reviewed for deriving CBF from the residue function. Procedures that involve deconvolution, such as Fourier deconvolution or singular value decomposition (SVD), are classified as model-independent methods because they do not require a model of the microvascular hemodynamics. Those methods in principle also yield a measure of the tissue impulse response function and the residue function, from which microvascular hemodynamics can be characterized. The second category of methods is the model-dependent methods, which use models of tracer transport and retention in the microvasculature. These methods do not yield independent measures of the residue function and may introduce bias when the physiology does not follow the model. Statistical methods are sometimes used, which involve treating the residue function as a deconvolution kernel and optimizing (fitting) the kernel from the experimental data using procedures such as maximum likelihood. Finally, other hemodynamic indices that can be measured from DSC-MRI data are described.

Blood Volume↗
PubMed1995

Fourier processing of liquid chromatograms using flow radioactive detection.

Flow radioactivity counters coupled to liquid chromatography devices cause a systematic bias to the separation by broadening peaks within the radiochromatogram. Such signal smearing may be evaluated on standardization runs with a single peak, using the ratio between Fourier transforms of whole chromatographic data for the measured radioactivity time series (radioactivity channel) and for the concentration time series (optical density channel). This ratio constitutes a kernel suitable to perform the deconvolution of any radiochromatogram performed under similar conditions. Through deconvolution, the signal smearing is removed, reverting to peaks with the same geometry as in the concentration chromatogram: same retention time, peak width, and shape. The deconvolution method in processing radiochromatograms allows an easier interpretation and gives more reliable radioactivity quantification (improved linearity of the measured response). Fourier transformation of the radiochromatogram also allows the removal of transitory events (noise) through the correlation procedure. This method may provide substantial gain in sensitivity, depending upon the residence time of the sample in the counting cell.

Chromatography, Liquid↗
PubMed1995

A hybrid-hybrid matrix method for 3D NOE-NOE data analysis.

A hybrid-hybrid matrix method is described that quantitatively analyzes 3D NOE-NOE NMR data. Experimental 3D data are merged with simulated 3D data to create a hybrid 3D NOE-NOE spectrum. This is then deconvoluted into a 2D hybrid NOESY spectrum. The deconvoluted, 2D hybrid NOESY spectrum can then be merged with other 2D NOESY experimental data along with additional simulated 2D data as necessary to create a hybrid-hybrid 2D NOE volume matrix. This hybrid-hybrid volume matrix is then used with the complete relaxation program, MORASS, to calculate a rate matrix, and the resulting distances taken from the off-diagonal cross-relaxation rates can then be utilized in a distance geometry or restrained molecular-dynamics refinement of the structure. This process is repeated until a satisfactory agreement between the calculated and observed 3D volumes is obtained. This hybrid-hybrid matrix method retains computational efficiency and utilizes the resolution of the 3D data set while retaining any information content of the available 2D data. The initial tests of the deconvolution algorithm give high correlation results even with the introduction of random error into the 3D data set. Our results suggest that the hybrid-hybrid matrix method for analysis of 3D NOE-NOE spectra may provide a viable tool in the refinement of large molecules.

Algorithms↗
PubMed1995

Limitations of the maximum entropy principle in devising drug input rate.

A computer program applying the principle of maximum entropy to the analysis of drug absorption rate has been developed. Plasma concentrations of amoxicillin obtained after oral and intravenous dosing have been analysed, together with simulated data corresponding to a complex input. Amoxicillin absorption rates devised by the program were similar to those obtained by a standard deconvolution method, although they were displayed as an almost continuous profile. However, improbable fluctuations were obtained with some data sets and the fraction absorbed was underestimated by 13%. With the simulated data, the maximum entropy program did not provide a better solution than the standard deconvolution procedure, and it was sensitive to the addition of random error and to the number of samples. The maximum entropy principle, as implemented in our computer program, may not have a better performance than standard deconvolution procedures, especially in human experiments where the number of blood samples is usually limited.

Administration, Oral↗
PubMed1989

Factor analysis of dynamic structures (FADS) in the diagnosis of renal disease.

Factor analysis of dynamic structures (FADS) has been used in the interpretation of dynamic scintigraphic studies since the technique was described by Bazin et al. (1980). This study was designed to analyse to what extent, if any, does physiological factor analysis of dynamic renal data really help the clinician and by how much the method improves the diagnostic accuracy when compared to deconvolution analysis and parenchymal transit time (PTT) measurements. One hundred and fifty patients who were clinically, biochemically and radiologically investigated for renal disease were included in the study. Fifty of these were found to have no clinical evidence of renal disease, 50 were diagnosed as having non obstructive kidney disease and 50 had evidence of renal obstruction. Data obtained from 99mTc-DTPA renography were processed using deconvolution (with PTTs) and physiological factor analysis and the results compared by ROC analysis. Clinically the information gained from factor analysis was superior to that obtained from deconvolution with PTT measurements in that a more accurate differentiation between an obstructive nephropathy and an obstructive uropathy was obtained. It is considered that physiological factor analysis enhanced the clinical information obtained from renography, increases diagnostic accuracy and obviates the need for diuresis renography.

Humans↗
PubMed1997

Nonclassical secretory dynamics of LH revealed by hypothalamo-hypophyseal portal sampling of sheep.

Continuous withdrawal of hypophyseal portal blood from unrestrained sheep has permitted detailed assessments of the pulsatile secretion of gonadotrophin-releasing hormone (GnRH). To determine if this blood can also be used to characterize the sensory dynamics of pituitary hormones, patterns of luteinizing hormone (LH) in the hypophyseal portal blood of ovariectomized ewes was compared with previous patterns of GnRH and peripheral LH. Hypophyseal portal blood and jugular vein blood were collected every 5 min from six ovariectomized ewes over 6-12 h. Hypophyseal portal blood contained GnRH-associated, sharply defined LH pulses that were much larger than in the periphery. Pulses of secreted LH (hypophyseal portal LH less peripheral LH) showed much faster rates of rise and fall than peripheral and followed pulses of GnRH by an average of 1.26 min. In contrast to pulses in jugular blood, secreted LH pulses often reached a relatively unchanging interpulse nadir-plateau and thereby approached closely algorithm-estimated, extrapolated baselines. The interpulse baseline concentrations of secreted LH (99.6 ng/mL) in hypophyseal portal blood were 31-fold higher than those for jugular LH (3.23 ng/mL). These elevated concentrations also exceeded mean jugular peak concentrations (11.1 ng/mL) and, thus, primarily must represent newly secreted LH. The non-Gaussian profiles of this secreted LH were substantially more complex than the inputs predicted from jugular LH measurements by deconvolution. Furthermore, regardless of the analytical approach, estimations of the mass of secreted LH in each pulse did not correlate well with inputs predicted by deconvolution or Kushler-Brown pulsefit analysis of corresponding pulses in jugular blood (r2 ranging 0.40-0.48). Among alternative explanations is the possibility of heterogeneity in concentrations of GnRH in the portal vessels and variable distribution within the hypophysis. In summary, assay of hypophyseal portal blood obtained directly from the pituitary provides a method for direct assessment of secretory responses to hypothalamic peptides, and thereby serves as an unmatched method for studying the dynamics of LH secretion in vivo. With this approach, LH is revealed to be secreted as complex, non-Gaussian pulses that are far more sharply defined that those in the periphery, include non-GnRH-dependent, secretory components that cannot be predicted by deconvolution and are followed by periods of relatively constant, basal secretion.

Algorithms↗
PubMed2002

The conscious Göttingen minipig as a model for studying rapid pulsatile insulin secretion in vivo.

AIMS/HYPOTHESIS: Pulsatile secretion is important for insulin action and suitable animal models are important tools for examining the role of impaired pulsatile insulin secretion as a possible link between beta-cell mass, function and morphology and insulin resistance. This study examines the vascular sampling site, insulin kinetics, pulsatility and the response to glucose pulse entrainment to evaluate the Göttingen minipig as a model for studying pulsatile insulin secretion. METHODS: Basal and glucose entrained insulin secretion was examined in normal minipigs and evaluated by autocorrelation, cross correlation and deconvolution. RESULTS: Cross correlation showed a relation between oscillations in insulin concentrations in the portal and jugular vein in anaesthetised animals ( p<0.001 in all animals), confirming the usefulness of jugular vein sampling for pulse detection. Jugular vein sampling in conscious animals showed obvious oscillations allowing estimates of burst shape and insulin kinetics. Glucose entrainment improved the pulsatile pattern (autocorrelation: 0.555+/-0.148 entrained vs 0.350+/-0.197 basal, p=0.054). Deconvolution analysis resolved almost all insulin release as secretory bursts (69+/-20 basal vs 99.5+/-1.2% entrained, p<0.01) with a pulse interval (min) of 6.6+/-2.2 (basal) and 9.4+/-1.5 (entrained) ( p<0.05) and a pulse mass (pmol/l per pulse) which was higher after entrainment (228+/-117 vs 41.2+/-18.6 basal, p<0.001). CONCLUSION/INTERPRETATION: The ability to fit kinetic parameters directly by deconvolution of peripheral endogenous insulin concentration time series in combination with the suitability of jugular vein sampling, rapid kinetics and entrainability makes the Göttingen minipig ideal for mechanistic studies of insulin pulsatility and its effects on insulin action.

Anesthesia, General↗
PubMed2001

Quantification of beta-cell function during IVGTT in Type II and non-diabetic subjects: assessment of insulin secretion by mathematical methods.

AIMS/HYPOTHESIS: We compared four methods to assess their accuracy in measuring insulin secretion during an intravenous glucose tolerance test in patients with Type II (non-insulin-dependent) diabetes mellitus and with varying beta-cell function and matched control subjects. METHODS: Eight control subjects and eight Type II diabetic patients underwent an intravenous glucose tolerance test with tolbutamide and an intravenous bolus injection of C-peptide to assess C-peptide kinetics. Insulin secretion rates were determined by the Eaton deconvolution (reference method), the Insulin SECretion method (ISEC) based on population kinetic parameters as well as one-compartment and two-compartment versions of the combined model of insulin and C-peptide kinetics. To allow a comparison of the accuracy of the four methods, fasting rates and amounts of insulin secreted during the first phase (0-10 min) and the second phase (10-180 min) were calculated. RESULTS: All secretion responses from the ISEC method were strongly correlated to those obtained by the Eaton deconvolution method (r = 0.83-0.92). The one-compartment combined model, however, showed a high correlation to the reference method only for the first-phase insulin response (r = 0.78). The two-compartment combined model failed to provide reliable estimates of insulin secretion in three of the control subjects and in two patients with Type II diabetes. The four methods were accurate with respect to mean basal and first-phase secretion response. The one-compartment and two-compartment combined models were less accurate in measuring the second-phase response. CONCLUSION/INTERPRETATION: The ISEC method can be applied to normal, obese or Type II diabetic patients. In patients with deviating kinetics of C-peptide the Eaton deconvolution method is the method of choice while the one-compartment combined model is suitable for measuring only the first-phase insulin secretion.

Adult↗
PubMed1992

Analysis of the circular dichroism spectrum of proteins using the convex constraint algorithm: a practical guide.

Due to the time scale of circular dichroism (CD) measurements, it is theoretically possible to deconvolute such a spectrum if the pure CD spectra differ significantly from one another. In the last decade several methods have been published aiming at obtaining the conformational weights, or percentages (which are the coefficients for a linear combination) of the so-called typical secondary structural elements making up the three-dimensional structure of proteins. Two methods that can be used to determine the secondary structures of proteins are described here. The first method, called LINCOMB, is a simple algorithm based on a least-squares fit with a set of reference spectra representing the known secondary structures and yielding an estimation of weights attributed to alpha-helix, beta-pleated sheet (mainly antiparallel), beta-turns, unordered form, and aromatic/disulfide (or nonpeptide) contributions of the protein being analyzed. This method requires a "template" or reference curve set, which was obtained from the second method. The second method, "convex constraint analysis," is a general deconvolution method for a CD spectra set of any variety of conformational type. The algorithm, based on a set of three constraints, is able to deconvolute a set of CD curves to its common "pure"-component curves and conformational weights. To analyze a single CD spectrum with this method, the spectrum is appended to the data set used as a reference data set. As a way to determine the reliability of the algorithm and provide a guideline to its usage, some applications are presented.

Algorithms↗
PubMed1987

Circular dichroism and magnetic circular dichroism spectra of chlorophylls a and b in nematic liquid crystals. II. Magnetic circular dichroism spectra.

Absorption and magnetic circular dichroism (MCD) spectra are reported for chlorophyll (Chl) a and Chl b dissolved in nematic liquid crystal solvents. The spectra were measured with the dye molecules oriented uniaxially along the direction of. the magnetic field and measuring light beam. It is significant that under such conditions the MCD spectra recorded in the wavelength region of the Q and Soret bands of the chlorophyll are essentially unchanged with respect to rotation of the sample cell around this axis, even though there is almost complete orientation of the chlorophyll molecules by the liquid crystals. The MCD spectra of Chl a and b in the nematic liquid crystal solvents used in this study are surprisingly similar to the spectra obtained under isotropic conditions. These results illustrate an important technique with which to examine the optical spectra of dyes oriented in liquid crystal matrices in which the anisotropic effects can be reduced the negligible proportions by the application of a strong magnetic field parallel to the direction of the measuring light beam. The first deconvolution calculations are reported that describe the deconvolution of pairs of absorption and MCD spectra, in the Q and B band regions, for both Chl a and b. The spectral analysis to obtain quantitative estimates of transition energies was accomplished by carrying out detailed deconvolution calculations in which the both the absorption and MCD spectral envelopes were fitted with the same number of components; each pair of components had the same hand centres and bandwidth values. This procedure resulted in an assignment of each of the main transitions in the absorption spectra of both Chl a and b. Chl a is clearly monomeric, with Qy, Qx, By and Bx located at 671, 582, 439 and 431 nm, respectively. Analysis of the spectral data for Chl b located Qy, By and Bx, at 662, 476 and 464 nm, respectively.

Journal Article↗
PubMed1995

Photoacoustic diagnostics of fast photochemical and photobiological processes. Analysis of inverse problem solution.

Photoacoustic (PA) diagnostics is a time-resolved experimental technique that measures transient photoinduced volume changes on the nano- and microsecond time-scales. The technique has been used to study the energetics and dynamics of chemical and biochemical reactions initiated by absorption of light. The dynamics of the volume changes and associated relaxation processes can be restored from PA-waveforms by solving an ill-posed problem of deconvolution. For the systems with known relaxation kinetics scheme this problem is usually solved by an iterative approximation algorithm. In complex photoactive systems (e.g. photosynthetic samples), where information about kinetics of fast photoinduced volume changes is not available, an algorithm of direct deconvolution must be used. The implementation of one of the linear deconvolution algorithms (Tikhonov's alpha-regularization) for the PA-diagnostics is therefore considered. The problem of the optimal choice of experimental set-up, and restoration algorithm is analyzed by a numerical simulation. It is shown that the quality of PA-diagnostic experiment is mainly determined by a transfer function converting the relaxation spectrum to the spectrum of output electric signal. The analytical expressions to calculate this function (so called PA-filter) are presented. The performance of two widely used schemes of PA-diagnostics are then directly compared. The time-resolution of the PA-diagnostics in analysis of simultaneous bi-exponential decay is evaluated, and the relationship between the resolving power and parameters of the experimental set-up (signal-to-noise ratio, sampling rate, shape of the PA-filter) is found. The advantage of front face irradiation scheme with piezopolymer film detector for time-resolved measurements is demonstrated.

Journal Article↗
PubMed2004

Components and fractions for differently bound water molecules of dipalmitoylphosphatidylcholine-water system as studied by DSC and 2H-NMR spectroscopy.

Differently bound water molecules of dipalmitoylphosphatidylcholine (DPPC)-H2O system were investigated with differential scanning calorimetry (DSC). According to a method previously reported by us, the ice-melting DSC curves of the DPPC-H2O samples of varying water contents were deconvoluted into multiple components, and the ice-melting enthalpies for the individual deconvoluted components were used to estimate average molar ice-melting enthalpies for freezable interlamellar and bulk waters, respectively. With these average molar ice-melting enthalpies, the numbers of differently bound water molecules of the DPPC-H2O system were calculated at varying water contents and were used to construct a water distribution diagram of this system. Furthermore, to evaluate the reliability of the present DSC deconvolution method, 2H-NMR T1 measurements of DPPC-2H2O system were carried out at 5 degrees C of the gel phase temperature, and components and fractions for differently bound water (2H2O) molecules were estimated from the analysis of nonexponential magnetization recovery curves.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2004

UV spectroscopy: a tool for monitoring humification and for proposing an index of the maturity of compost.

Composting organic matter is an interesting way to valorize waste. Compost is a product obtained after a humification process. The humification of organic matter during composting was studied by the quantification and monitoring of the evolution of humic substances. The final objective was to be able to evaluate the state of humification based on a spectrum of total humic substances using the method of UV spectral deconvolution. This study presented a new index obtained by UV spectroscopy using the deconvolution of an unknown spectrum of compost with 3 reference spectra. This index was compared to the maturity indices usually used, such as total extraction of humic substances (rate of extraction), IP (index of polymerization) or the humic acid to fulvic acid ratio. This new parameter, which was easy and quick to determine, gave precise information about the quality of the compost. It made it possible to disregard the values of aberrant concentrations caused by the classical protocol of extraction. Compared to the humic acid to fulvic acid ratio, the new index obtained by UV spectral deconvolution showed more representative results: the humic acid to fulvic acid ratio for an apparently non-mature compost was abnormally high, suggesting that the compost was mature, whereas the UV index proposed showed that the compost was really young and not yet humified.

Benzopyrans↗
PubMed2004

A Structural-informatics approach for tracing beta-sheets: building pseudo-C(alpha) traces for beta-strands in intermediate-resolution density maps.

We report the development of two computational methods to assist density map interpretation at intermediate resolutions: sheettracer for building pseudo-C(alpha) models of beta-sheets, and a deconvolution method for enhancing features attributed to major secondary structural elements. Sheettracer is tightly coupled with sheetminer, which was developed to locate sheet densities in intermediate-resolution density maps. The results from sheetminer are used as inputs to sheettracer, which employs a multi-step ad hoc morphological analysis of sheet densities to trace individual strands of beta-sheets. The methods were tested on simulated density maps from 12 protein crystal structures that represent a reasonably complete sampling of sheet morphology. The sheet-tracing results were quantitatively assessed in terms of sensitivity, specificity and rms deviations. Furthermore, sheettracer and the deconvolution method were rigorously tested on experimental maps of the lambda2 protein of reovirus at resolutions of 7.6A and 11.8A. Our results clearly demonstrate the capability of sheettracer in building pseudo-C(alpha) models of beta-sheets in intermediate-resolution density maps and the power of the deconvolution method in enhancing the performance of sheettracer. These computational methods, along with other related ones, should facilitate recognition and analysis of folding motifs from experimental data at intermediate resolutions.

Algorithms↗
PubMed2006

Enhanced resolution for EPR imaging by two-step deblurring.

The broad spectrum of spin probes used for electron paramagnetic resonance imaging (EPRI) result in poor spatial resolution of the reconstructed images. Conventional deconvolution procedures can enhance the resolution to some extent but obtaining high resolution EPR images is still a challenge. In this work, we have implemented and analyzed the performance of a postacquisition deblurring technique to enhance the spatial resolution of the EPR images. The technique consists of two steps; noniterative deconvolution followed by iterative deconvolution of the acquired projections which are then projected back using filtered backprojection (FBP) to reconstruct a high resolution image. Further, we have proposed an analogous technique for iterative reconstruction algorithms such as multiplicative simultaneous iterative reconstruction technique (MSIRT) which can be a method of choice for many applications. The performance of the suggested deblurring approach is evaluated using computer simulations and EPRI experiments. Results suggest that the proposed procedure is superior to the standard FBP and standard iterative reconstruction algorithms in terms of mean-square-error (MSE), spatial resolution, and visual judgment. Although the procedure is described for 2D imaging, it can be readily extended to 3D imaging.

Algorithms↗
PubMed2006

Component analysis of the fluorescence spectra of a lignin model compound.

In order to test whether lignin fluorescence originates from discrete fluorophores, fluorescence emission spectra of the lignin model dehydrogenative polymer (DHP) were analyzed by the band deconvolution method and time-resolved analysis of both the excitation and emission spectra. Two series of 22 fluorescence emission spectra of DHP in chloroform/methanol (3:1, v/v) solution, and as a solid suspension in water, were deconvoluted into three fluorescence and one Raman Gaussian components. Emission spectra were obtained by stepwise variation of the excitation wavelength from 360 to 465 nm. Deconvolution was performed by nonlinear fitting of all three Gaussian parameters: area, width and position. Position of all components in a series was treated as a random variable and its approximate probability distribution (APD) calculated from a series of histograms with increasing number of abscissa intervals. A five peak multimodal APD profile was obtained for both series of DHP emission spectra. The mean fluorescence lifetime varied with wavelength both in the emission and the excitation decay-associated spectra (DAS), where four kinetic components were resolved. The shapes of the excitation spectra of the four components were quite different and gradually shifted bathochromically. The multicomponent nature of the DHP emission spectra along with the changes in the mean fluorescence lifetime and the form of the excitation DAS of the four components give evidence of the heterogeneous origin of fluorescent species emitting in the visible.

Chloroform↗
PubMed2006

Comparison of Si and Ge low-loss spectra to interpret the Ge contrast in EFTEM images of Si(1-x) Ge(x) nanostructures.

Recently, an EFTEM imaging method, exploiting the inelastically scattered electrons in the 60-90eV energy range, was proposed to visualise Ge in SiGe alloys [Pantel, R., Jullian, S., Delille, D., Dutartre, D., Chantre, A., Kermarrec, O., Campidelli, Y., Kwakman, L.F.T.Z., 2003. Inelastic electron scattering observation using Energy Filtered Transmission Electron Microscopy for silicon-germanium nanostructures imaging. Micron 34, 239-247]. This method was proven to be highly more efficient in terms of noise, drift and exposure time than the imaging of the weak and delayed ionization GeL2,3 edge at 1236eV. However, the physical phenomenon behind this Ge contrast was not clearly identified. In this work, we explain the origin of this Ge contrast, by comparing in details EELS low-loss spectra (<100eV) recorded from pure Si and Ge crystals. High resolved low-loss experiments are performed using analytical Field Emission Gun Transmission Electron Microscopes fitted or not with a monochromator. Low-loss spectra (LLS) are then deconvoluted from elastic/quasi-elastic and plural scattering effects. The deconvolution procedure is established from Si spectra recorded with the monochromated machine. The absence of second plasmon and the measurement of a band gap (1.12eV) on the Si single scattering distribution (SSD) spectrum allowed us to control the accuracy of the deconvolution procedure at high and low energy and to state that it could be reliably applied to Ge spectra. We show that the Ge-M4,5 ionisation edge located at 29eV, which is shadowed by the high second plasmon in the unprocessed Ge spectrum, can be clearly separated in the single scattering spectrum. We also show that the front edge of Ge-M4,5 is rather sharp which generates a high intensity post edge tail on several tens of eV. Due to this tail, the Si and Ge EELS signals in the 60 to 100eV energy window are very different and the monitoring of this signal gives information about the Ge concentration inside SiGe alloys. It is now evident that the EFTEM imaging technique proposed to quantify Ge (90eV/60eV image ratio) in Si-Ge nanostructures is valid and is a relevant way of exploiting the Ge-M4-5 ionisation edge.

Journal Article↗