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Figure 5
Influence of the speed of acquisition on the signal-to-noise ratio. Four different acquisition time constants (TC set in the lock-in amplifier) resulting in different acquisition speeds demonstrate the signal-to-noise behaviour. (a) 300 ms; (b) 100 ms; (c) 30 ms; (d) 10 ms. The acquisition time per data point corresponds to four times the time constant, also referred to as the integration time. Residuals are overlayed. Three full consecutive scans of myoglobin, 10 mg ml−1 in a 15 µm pathlength [raw data, black squares (red online)], have been measured for each dataset, including the return of the monochromator, and the stepping mode of the monochromator of theoretical speed 50 nm min−1 (corresponding to 1.2 s integration time) is reduced to a scan speed of 35 nm min−1. Therefore three consecutively acquired spectra with good signal-to-noise ratio are currently produced within 9 min. The residual in percentiles [grey line (green online)] is superimposed on the zero line.

Journal logoJOURNAL OF
SYNCHROTRON
RADIATION
ISSN: 1600-5775
Volume 19| Part 5| July 2012| Pages 831-835
doi:10.1107/S0909049512030002
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