Pulse baseline shift

Figure 4.21 Baseline shift due to a regular series of identical pulses. The total areas above and below the baseline are equal...

Coincidence and Dead-time Losses in y-Spectrometry. The influence of electronic effects at high-count rates on the performance of Ge(Li) detectors is considerable. The resolution of a detector can be degraded by effects within the amplification system, but these can be minimized by (i) the use of pole-zero cancellation, to prevent the pulse-height error caused by the tail of a preceding pulse and (n) baseline (or D.C.) restoration facilities to prevent similar errors caused by shifts in the apparent pulse baselines. The latter are a result of capacitative effects between the various stages of the overall amplifier, biased amplifier, and multi-channel analyser system. These effects can degrade the resolution of the detector but should not change the y-ray peak area. 

The H-NMR spectra of FCC feeds were recorded on a Bruker DRX 400 MHz NMR spectrometer. The concentration of the samples of 5 wt% in CDCI3 was recommended by Molina, Navarro Uribe, and Murgich [2] to avoid concentration dependence of the chemical shift. A 30° pulse sequence was applied, with 4.089 s acquisition time, 2 s pulse delay [2], 8012.8 Hz spectral width, and 64 scans. Hexamethyldisiloxane (HMDSO) was used as a reference. NMR processing was realized using MestReNova software. The phase and baseline of the resulting spectra were manually adjusted and corrected. The spectra were integrated six times and average values were taken for the purpose of calculations. The spectra were divided... 

A MicroCal MC-2 scanning calorimeter (MicroCal Inc., North Hampton, MA.) was used to perform the thermal denaturation experiments. Sample and reference volume used was 1.2 ml and enzyme concentrations ranged from 1 to 5 mg/ml. Baseline and shift settings were adjusted to give a flat water-water baseline. Cell feedback was fixed at a value of 32 and 16X sensitivity and 0.5oC/min scan rate were used. Following a scan, a 4X calibration pulse was used to scale the endotherm in practice, little instrumental drift was observ. ... 

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