Analytic techniques scattering

Analytical techniques. See also Light scattering technique One-shot technique TEM technique ... 

Electron energy loss spectroscopy An analytical technique used to characterize the chemistry, bonding, and electronic structure of thin samples of materials. It is normally performed in a transmission electron microscope. The inelastically scattered electron beams are spectroscopically analyzed to give the energy spectrum of electrons after the interaction. 

As micro-analytical techniques (performing direct analysis on a <10 mg sample mass) have a particularly distinct demand for very homogeneous CRMs, it becomes necessary to provide element-specific homogeneity information in the CRM certificates. The distribution of elements in a material can be evaluated experimentally by repetitive analysis. The scattering of results from a method with known intrinsic precision is related to the mass of sample consumed for individual analysis. The... 

Practically all classical methods of atomic spectroscopy are strongly influenced by interferences and matrix effects. Actually, very few analytical techniques are completely free of interferences. However, with atomic spectroscopy techniques, most of the common interferences have been studied and documented. Interferences are classified conveniently into four categories chemical, physical, background (scattering, absorption) and spectral. There are virtually no spectral interferences in FAAS some form of background correction is required. Matrix effects are more serious. Also GFAAS shows virtually no spectral interferences, but... 

Analysis by the Detection of Scattered Ions. Ions generally penetrate the specimen much less deeply than electrons of equivalent energy, so they are more surface-sensitive. Ion-based surface analytical techniques are popular because of their sensitivity and their ability, in some cases, to reveal the depth composition profile. 

The replacement of OES by AAS in Oxford in 1976 immediately called into question the long-term compatibility of the huge analytical database amassed by OES with subsequent analytical techniques. Detailed intertechnique comparisons were carried out, both in Oxford (Hatcher et al. 1980) and elsewhere (White 1981). Both pointed toward the same conclusion OES data are generally more scattered, and systematic differences of calibration occur between OES and AAS. Hatcher et al. contemplated the use of... 

All analytical techniques in the TEM are based on the inelastic scattering of the fast beam electrons by the electrons of the atoms in the material investigated. The primary event in each case is the transfer of energy and momentum from the fast electron to a sample atom, thereby exciting the... 

Since the development of HPLC as a separation technique, considerable effort has been spent on the design and improvement of suitable detectors. The detector is perhaps the second-most important component of an HPLC system, after the column that performs the actual separation it would be pointless to perform any separation without some means of identifying the separated components. To this end, a number of analytical techniques have been employed to examine either samples taken from a fraction collector or the column effluent itself. Although many different physical principles have been examined for their potential as chromatography detectors, only four main types of detectors have obtained almost universal application, namely, ultraviolet (UV) absorbance, refractive index (RI), fluorescence, and conductivity detectors. Today, these detectors are used in about 80% of all separations. Newer varieties of detector such as the laser-induced fluorescence (LIE), electrochemical (EC), evaporative light scattering (ELS), and mass spectrometer (MS) detectors have been developed to meet the demands set by either specialized analyses or by miniaturization. 

A variety of analytical techniques were then used to verify that Cd(OH)2 was present in the solution when the complex Cd ratio was below the critical value (Re) but absent above it. Cd(OH)2 absorbs in the UV range of the spectrum, and spectral monitoring of Se-free solutions showed that it was present only below Rc. Light scattering by a blue laser also confirmed the presence of a heterogeneous phase below Rc but not above it. Similar XPS analyses to those employed by Rieke and Bentjen for CdS showed that Cd adsorbed on the glass substrate, immersed in Se-free solutions, only below Rc. This is seen in Table 3.1 Appreciable amounts of Cd (as Cd(OH)2) were seen only when the pH was sufficiently high and the complex Cd ratio relatively low. 

Diffuse reflectance differs from classical transmission in which no particulate matter exists to scatter the beam of radiation. It is necessary to contrast correlation spectroscopy (correlation analytical techniques based on spectroscopic measurements) to a classical, one wavelength, monochromatic application of Beer s law. The use of multiple wavelengths produces a multiterm analytical equation in reflectance R of the general type ... 

Asbestos can be determined by several analytical techniques, including optical microscopy, electron microscopy, X-ray diffraction (XRD), light scattering, laser microprobe mass analysis, and thermal analysis. It can also be characterized by chemical analysis of metals by atomic absorption, X-ray fluorescence, or neutron activation techniques. Electron microscopy methods are, however, commonly applied for the analysis of asbestos in environmental matrices. 

---