Fig. 4: Variable temperature vibrational Raman spectroscopy.
From: Normal & reversed spin mobility in a diradical by electron-vibration coupling
Solid-state variable temperature Raman spectra of CAR taken with the 785 nm (a) and (b) and with 633 nm excitation wavelength (c) and (d) in two different vibrational intervals where the four important (strongest) bands are denoted as (1) ν(CC)ph; (2) ν(CC)phO; (3) ν(CN)azo1; and (4) ν(CN)azo2. e Representation as a function of the temperature of the ratio of intensities of 1 (A1) and 2 (A2) as black circles and 3 (A3) and 4 (A4) bands as red squares as spectroscopic markers of the degree of quinoidal/aromatic character, which delineates three regions: small ratio means more quinoidal, large ratio more aromatic and pseudoquinoidal (PQ) is in between. f Topologies of the vibrational modes from the theoretical Raman spectra in Supplementary Figs. 12–14.
