Fig. 2: Determining the crystal orientation of MoO₃ through Raman spectroscopy.

a Raman spectra at 0° (blue), 45° (black) and 90° (red) angles with respect to the horizontal axis. A_g^c, B_2g and A_g^a Raman modes are highlighted with vertical dashed lines. Inset: Microscopy image of the sample placed in the initial position (0°) and the a and c axes, determined from the angle-resolved Raman measurements, are shown. b Polar plots, in light red; and fittings, in dark red, of angle-resolved normalized Raman intensities of the A_g^c (left), B_2g (middle) and A_g^a (right) modes.