Fig. 4: Molecular origins of I-II transition. | Nature Communications

Fig. 4: Molecular origins of I-II transition.

From: Unraveling two distinct polymorph transition mechanisms in one n-type single crystal for dynamic electronics

Fig. 4

Unit cell changes from polymorph I (blue) to polymorph II (green) (a). Frames from Supplementary Movie 7, during in situ GIXD (b). Changes to the (10) Bragg rod (c) reflecting the β-angle shift and (d) plot of qz peak position during the I-II transition. Packing of polymorphs I (e) and II (f) along the c-direction showing increased core tilt and reduced alkyl chain interdigitation. Polymorphs I (g) and II (h) along the a* direction with similar 1D π-stack motifs. Schematic of the CH2 deformation mode (δ(CH2), red) and quinoidal ECC (ν(C=C)ECC,Q, light blue) (i). Raman spectra intensity shifts in phonon region (j) and core C=C stretching region (k) with increasing temperature. Decrease in the intensity ratio of δ(CH2) to ν(C=C)ECC,Q (l), consistent with alkyl chain reorientation during transition. δ(CH2) peak position redshift at the transition temperature (m). Error bars reflect peak fitting error. Orange lines indicate transition temperatures.

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