Fig. 2
(a) Peak position vs. band depth of the composite waveform of the 2.7 µm band (red dots: chamber A particles, light blue dots: chamber C particles). Error bars show 2 sigma errors on the fitting analysis. The depth tends to be shallower at longer wavelengths. (b) For the trend observed in (a), the central straight black line passing through (2.71, 0) and (2.726, 30) is set as the threshold where the distributions of the particles are divided into two regions: short wavelength with deep depth, and long wavelength with shallow depth. Particles in each region are color-coded and named: long wavelength—deep depth region is named α (Aα: orange, Cα: blue), short wavelength—shallow depth region is named β (Aβ: pink, Cβ: dark blue). The mean value and the standard error of the peak positions for each group is Aα: 2.7143 ± 0.0001 µm, Aβ: 2.7193 ± 0.0003 µm, Cα: 2.7150 ± 0.0001 µm, and Cβ: 2.7186 ± 0.0004 µm. The depth is Aα: 18.0 ± 0.4%, Aβ: 10.9 ± 0.3%, Cα: 15.2 ± 0.3%, and Cβ: 12.1 ± 0.4%. There is a trend that the longer the peak position is, the shallower the depth is, in the groups from Aα to C (Cα to Cβ) to Aβ in the diagram, indicating that the chamber C particles mostly overlap with the Aα group, while partially extending toward the Aβ group.
