Figure 4
Calibration of the CD signal.
The CD signal intensity of the system was calibrated at a wavelength of 700 nm by measuring signal change when a sample with known small absorbance (fused silica substrate whose partial area was coated with Cr; 0.012 OD at 700 nm) was inserted between the two BDs in Fig. 1b. The differential optical intensity (ΔI) between the V- and H-beams (see Fig. 1b) when both beams are transmitted through the uncoated area of the calibration sample is referred to as the zero level of the signal. In the time region labelled ‘V’ and ‘H’, the Cr-coated area of the sample attenuated the V-beam and H-beam, respectively. The CD signal intensity was evaluated from the signal change and the known absorbance of the calibration sample. See the main text for more details.
