125471.fig.009a
(a)
125471.fig.009b
(b)
Figure 9: Polarized IR spectra of (a) d1-2-furanacetic acid and (b) d1-2-furanacrylic acid crystals measured at 77 K in the 𝜈 O - D band frequency range. (a) 2-Furanacetic acid crystal (ca. 10% H and 90% D). (I) The electric field vector 𝐸 parallel to the 𝑎 -axis, (II) The 𝐸 vector parallel to the 𝑐 *-axis. (b) 2-Furanacrylic acid crystal (ca 65% H and 35% D). (I) The electric field vector 𝐸 parallel to the c-axis, (II) The E vector parallel to the 𝑎 *-axis.