Figure 3.

Deviatoric stresses induce new radiative transitions in semiconductor nanocrystals. Fluorescence peak positions in CdSe/CdS a) dots, b) rods, c) tetrapods. Unfilled symbols denote the peak positions in 1:1 pentane:isopentane; filled symbols denote the peak positions in toluene. Under non-hydrostatic pressure, three radiative transitions are observed in dots and two radiative transitions are observed in rods and tetrapods. Insets in a)–c) provide a magnification of the emission points at the transition ~1.9 eV, with x-axis 0–6 GPa and y-axis 1.879–1.937 eV; linear fit provides a guide to the eye. d) Percentage of particles emitting in the transition ~1.9 eV under compression in toluene. Less than 50% of dots (circles) and rods (rod-shapes) emit at this transition, while nearly 100% of tetrapods (crosses) do. e) A difference plot of the fluorescence peak maxima for CdSe/CdS tetrapods compressed in hydrostatic and non-hydrostatic media provides a measure of the net deviatoric stress effect—which induces tetrapod arm bending—on tetrapod emission. A fluorescence peak red-shift due to non-hydrostatic stress on the order of nanonewtons per particle is observed (see discussion). The linear fit shown provides a guide to the eye. Error bars show the standard error of peak position from the fit.