Influence of stray light

Slffty linht is usually specified at 220 nm In the case of low cost instru-mentiiiuR ii amutinli tu /, OJHi. tniiiaMi a mai transmlitanea af the sample of 1% (absorbance a2) the spectrometer reads 1.2% (Ess 1.922). That means the absolute error amounts to 4%. (For real E = 3, / =0.2%, 

Additional errors can arise if the sample measured is not homogeneous (streak formation in micro cells). Furthermore interference to the beam of measurement by either the walls, the bottom of the cells, or the interface between solution and air must be avoided. 

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Little attention has been given to the influence of these transient liquid mirrors and lenses on the amount of stray light reaching the detector. Investigation of this process is strongly recommended, as the Schlieren effect can lead to an increase in detected radiation, hence degrading the linearity of the analytical response curve [13]. 

Ultraviolet spectrophotometers cont.), single-beam, 225 standardisation, 226 Ultraviolet spectrophotometry, 221-232 absorption cells, 226 colorimetry, 228 derivative, 230 difference method, 229 dual-wavelength, 229 identification by, 231 influence of pH, 224 influence of solvent, 224 laws of absorption, 222 quantitative applications, 227 stray-light effects, 224 Ultraviolet-visible detector, 202 multiwavelength, 211 Unicontin, 1011 Unidiarea, 474 Unidone, 356 Uniflu, 557, 893 Unilobin, 709 Unimycin, 846 Uniphyllin, 1011 Uniprofen, 677 Unisom, 576... 

Figure 11 Comparative influence of ambient stray light and sample fluorescence on scanning and diode array instrumentation,...

In Table 3 some essential parameters are listed, which should be referred to in a manual, since they influence the performance of a spectrometer in addition to such common parameters as range, accuracy, and reproducibility of wavelength, stray light bandpass (spectral bandwidth or slit width of the spectrometer) photometric accuracy, reproducibility, and linearity baseline flatness absorbance zero stability noise level scan speeds response times and data intervals. Furthermore possible modes of the axis are of interest absorbance, transmittance, derivative, Kubelka-Munk function [9], and the possible scaling of the axis. Most of these parameters are given in manuals, determine the limitations of the instrument, and affect each other. 

The de Gennes equations have been reexamined by Chen et al. [31], who discussed experimental limitations as boundary influences and finite sample dimensions. Possible error sources are stray light in the detector and inaccurate adjustment of the sample cell, which may lead to systematic errors in the scattering angle. 

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