Fig. 2
From: The valley Zeeman effect in inter- and intra-valley trions in monolayer WSe2
Trion photoluminescence in WSe2. a Photoluminescence (PL) spectrum from the sample under non-resonant laser excitation at 4.2 K. Peaks attributed to the neutral A-exciton (X0) and trion (X−) can be seen. The trion linewidth is 3.8 meV. b Temperature dependence of the trion photoluminescence from 4.2 to 30 K. Increasing thermal population of the higher energy triplet states can be inferred from the increasing spectral weight of the high energy shoulder of the trion peak, indicated by the black arrows. c PL spectrum from the sample at 30 K, fitted to five lorentzian peaks corresponding to various optically active states. The trion peak is well fitted to two peaks corresponding to the fine structure components, separated by ~4 meV. The navy blue peak may be the recently reported negatively charged biexciton, XX−, ~50 meV below X0
