Abstract: This work investigates the Mn2+ electronic structure and exciton dynamics in one-dimensional (1D)
N(CH3)4MnCl3 (TMMC) through time-resolved excitation/emission spectroscopy and absorption measurements
in the 0–10 GPa pressure range for different Cu2+ doping concentrations. The local and crystal structures have
been analyzed by Raman spectroscopy and x-ray absorptionmeasurements at theMnK edge showing that the 1D
chain structure is maintained in the whole explored pressure range. We show that both the first Mn2+ absorption
band, 4T 1(G), and its associated emission band experience very large pressure redshifts, which are associated
with the crystal anisotropy providing large axial ligand fields at the Mn2+ 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 Cu2+-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 Cu2+ 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.