Weak signals causes

As seen from Spectrum B in Figure 2 weak signals caused by VAc polymer radicals were observed at saturated monomer concentration. However, no more distinct spectrum than this one has been obtained so... 

Fig. 28 Raman spectra of polymeric sulfur (S ) prepared by various methods [109,173], of large disordered rings (S ) [182], and of photo-induced amorphous sulfur (a-S) [119], respectively. The spectrum of a-S has been smoothed for clarity. The position of the stretching vibration of a-S is pressure-shifted to higher wavenumbers. The very weak signals in the spectra of Sj, at ca. 150 and 220 cm are probably caused by the presence of Sg. In addition, the weak shoulder at ca. 470 cm observed in spectra of Sj, may originate from Sg, too...

Helicase, impairment causes SG assembly Weak signal... 

When we average n spectra, the signal-to-noise ratio is improved by fn. To improve the signal-to-noise ratio by a factor of 2 requires averaging four spectra. To improve the sig-nal-to-noise ratio by a factor of 10 requires averaging 100 spectra. Spectroscopists record as many as 104 to 105 scans to observe weak signals. It is rarely possible to do better than this because instrumental instabilities cause drift in addition to random noise. 

A serious limitation is imposed to high-pressure experiments by the small size of the samples. Typical dimensions of the samples are in the range 200 x 200 x 40 pm. This small size causes weak signals and, especially in the case of absorption spectroscopy, it can be very difficult or even impossible to study doped samples. 

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