Background, generally interference

It is often better to do the normalisation on an elastic scattering resonance (section 4.6), where the decay to the ground state can occur through only one partial wave. This method was first introduced by Gibson and Dolder (1969). Interference with the nonresonant background generally introduces some complications (see Williams and Willis, 1975). The modifications required in the analysis due to spin are discussed fully by Andrick and Bitsch (1975). 

The suitability of MS detectors for quantitative analyses is debated. For example, ESI is a competitive process and, occasionally, matrix (background) material interferes with the ionization of the analyte [40]. These effects of ion suppression are especially aggravated when several species coelute, such as in the case of biological extracts or with direct infusion (without previous separation). Generally, hydrophilic species are more sensitive to ion suppression than hydrophobic ones, which tend to concentrate on the droplet surface during ESI [41]. In MALDI, the sample dispersion is often inhomogeneous or the matrix crystals unevenly distributed on the surface. A truthful representation of the sample composition is obtained exclusively upon thorough laser desorption of the entire spot. In addition, with some instruments the transmission of ions in the mass... 

Automated Extraction of Interference Functions. For the classical synthetic polymer materials it is, in general, possible to strip the interference function from the scattering data by an algorithm that does not require user intervention. Quantitative information on the non-topological parameters is lost (Stribeck [26,153]). The method is particularly useful if extensive data sets from time-resolved experiments of nanostructure evolution must be processed. Background ideas and references are presented in the sequel. 

Solvents such as chloroform, carbon tetrachloride, hexane and benzene gave absorption signals because of their non-specific absorption at the lead resonance line. Although these solvent peaks generally emerged well before the lead compounds, the use of the background corrector is recommended to eliminate these potential interferences. 

Background fluorescence from glass cut-off filters is generally much less when exciting in the near-IR as compared with the UV/visible. Interference filters for the near-IR are also readily available. 

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