Spin relaxation and magnetic properties of benzo-1,2,3-trithiolium radical cations

Abstract

Magnetic and dynamics properties of paramagnetic centers in various trithiolium cations were characterized by static magnetic susceptibility measurements and EPR spectroscopy. Magnetically correlated units consisting of at least pairs of spins with ferromagnetic exchange coupling were found in some trithioles. The rates of intramolecular spin diffusion and intermolecular spin hopping were estimated separately. The rates and the anisotropy (vJv• = 20-300) of spin dynamics were shown to depend on the molecular structure.

EPR study of spin and charge dynamics in slightly doped poly(3-octylthiophene)

“…This is typical for other sulfur-containing compounds, e.g., poly(tetrathiafulvalenes) [36], poly(bis-alkylthioacetylene) [44] and benzo-trithioles [52] in which sulfur atoms are involved in the conjugation. The shift of the g-factor from the ge-factor for a free electron is expressed by [53] g,-ge = ge2sPs(O)/AE,j, where ge = 2.00232, ps(0) is the spin density on the sulfur nucleus, Z~ = 0.047 eV is the constant of the spin-orbit interaction of the electron spin with the sulfur nucleus, AEnj is the energy of an electron excitation from the ground orbit to the nearest r~* and (r* orbits (AEn~.…”

“…In sulfur-based organic solids like, e.g., poly(bis-alkylthioacetylene) and poly(tetrathiafulvalene) in which electrons are localized mainly on the sulfur atom the effective g-factor of the PC is 2.014 ~< giso ~< 2.020 [52,[54][55][56][57].…”

Spin charge carrier dynamics in poly(bis-alkylthioacetylene)

“…It is typical for other sulfur-containing compounds, e.g., poly(tetrathiafulvalenes) (PTTF) [12,[19][20][21] and benzo-trithioles [22][23][24], in which sulfur atoms are involved into the conjugation. Taking into account that the overlapping integral I~_~ in such organic nsystems depends on the dihedral angle 0 (the angle between p-orbits of neighboring C-atoms) as I› oc coso [25,26], the shift of the g-factor from the g-factor for the free electron (ge = 2.00232) is expressed by a modified equation [27]:…”

“…), and k~ is a constant. The g-factor of PC in sulfur-containing solids in which electrons are localized mainly on the sulfur atom lies in the region of 2.014 ~< giso ~< 2.020 [22][23][24]28]. In tetrathiafulvalene (TTF) derivatives an unpaired electron is delocalized on 12 or more carbon atoms and four sulfur atoms leading to the decrease of both ps(0) and giso values [12].…”

“…In tetrathiafulvalene (TTF) derivatives an unpaired electron is delocalized on 12 or more carbon atoms and four sulfur atoms leading to the decrease of both ps(0) and giso values [12]. An additional fast spin motion takes place in the PTTF [9,12,24] leading to a further decrease in the ps(0) value, and therefore to the decrease of giso down to 2.007-2.014 depending on the structure and effective polarity in PTTF samples [9,12]. Due to the smaller g-factor in PATAC, one can expect a higher spin delocalization in this polymer as compared with the above mentioned organic semiconducting solids.…”