This work investigates the Mn${}^{2+}$ electronic structure and exciton dynamics in one-dimensional (1D) N(CH${}_3$)${}_4$MnCl${}_3$ (TMMC) through time-resolved excitation/emission spectroscopy and absorption measurements in the 0–10 GPa pressure range for different Cu${}^{2+}$ doping concentrations. The local and crystal structures have been analyzed by Raman spectroscopy and x-ray absorption measurements at the Mn $K$ edge showing that the 1D chain structure is maintained in the whole explored pressure range. We show that both the first Mn${}^{2+}$ absorption band, ${}^{4}T$${}_1\left(G\right)$, and its associated emission band experience very large pressure redshifts, which are associated with the crystal anisotropy providing large axial ligand fields at the Mn${}^{2+}$ site that increase with pressure. The red emission at 633 nm shows a large pressure variation of 22 nm/GPa (50 meV/GPa) making TMMC a suitable probe for using as a photoluminescence (PL) pressure gauge in the low-pressure regime. The energy-transfer exciton dynamics and trapping at non-PL centers have been explained through changes of the intrachain Mn-Mn exchange interaction and Cu${}^{2+}$-trap concentration carried out by applying pressure and doping, respectively. The model demonstrates that an increase of exchange interaction favors both the pumping capability and energy transfer yielding exciton migration. Under these conditions, we show that pressure enhances the PL efficiency of TMMC provided that the Cu${}^{2+}$ concentration responsible for the PL quenching is below 0.001 mol %. However, between 0.001% and 0.1%, the PL intensity reduces with pressure, and above 0.1%, the PL is practically quenched even at ambient conditions.

• Received 12 October 2013
• Revised 17 February 2014

DOI:https://doi.org/10.1103/PhysRevB.89.115120