Fig. 5: Structural parameters selected to represent the structural motion of the initial isomerization, dissociation of BiI₃, and coherent wavepacket.

a The mean Bi-I_b-I_c angle and I_a-Bi-I_b-I_c dihedral angle of the early isomer are shown in blue and red dots, respectively, with the corresponding standard deviations as error bars. b The mean Bi···I_c distance of BiI₃ undergoing dissociation and the root-mean-squared displacement (σ) obtained from the Debye-Waller factor (DWF) are shown in black and red squares, respectively, with the corresponding standard deviations as error bars. The insets in both a and b, show the snapshots of the molecular structure at some representative time delays. Green and purple spheres stand for Bi and I atoms, respectively, and three I atoms are labeled with a, b, and c. The structural parameters shown in (a) and (b) were obtained from the structural fit analysis on ΔS_iso(q, t). The error bars in (a) and (b) at time delays earlier than 175 fs are one-standard-deviation error values calculated from the covariance matrix of the coefficients of quartic polynomials used to model the parameters during the structural fit analysis. The error bars of structural parameters in a and b at time delays later than 175 fs are the averaged one-standard-deviation error values obtained from the fits starting from ~5000 random structures for each time delay. The error bars for the σ of the DWF at time delays later than 175 fs are the one-standard-deviation error values obtained from the fit performed at each time delay.