[MOS] Tomorrow 4/6 - Modern Optics and Spectroscopy Seminar with Tristan Shi (MIT - Nelson Group)

[Christine Brooks]

There will be a virtual Modern Optics and Spectroscopy Seminar held tomorrow, April 6 at 12pm. A Q&A segment will immediately follow the conclusion of the seminar.

Zoom link: https://mit.zoom.us/j/93720521901?pwd=Vmt0S2syUXJBS054SUhhNklKTzlEUT09
Password: 581336
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Tristan (Jiaojian) Shi
MIT – Nelson Group

“All-optical control of fluorescence blinking with ultrafast mid-infrared and terahertz pulses”

Photoluminescence intermittency is a ubiquitous phenomenon detrimentally reducing the temporal emission intensity stability of colloidal quantum dots (QD) and the emission quantum yield of their ensembles. Despite efforts for blinking reduction via chemical engineering of the QD architecture and its environment, the blinking dynamics still pose barriers to the application of QDs, particularly in single-particle tracking in native biological environments or in single-photon sources. We demonstrate all-optical suppression of quantum dot blinking using a compound experiment of visible and mid-infrared (MIR) pulse excitation. We show that low-field ultrafast MIR pulses (5.5 μm, 150 fs) can switch the emission from a charged, low quantum yield 'grey' state to the 'bright' state in CdSe/CdS core-shell quantum dots resulting in a significant reduction of the QD intensity flicker. Quantum-tunneling simulations suggest that the MIR fields remove the excess charge from trions with reduced emission quantum yield to restore higher brightness exciton emission. Our approach can be integrated with existing single-particle tracking or super-resolution microscopy techniques without any modification to the sample and translates to other emitters presenting charging-induced PL intermittencies, such as single-photon emissive defects in diamond and two-dimensional materials.



Christine Brooks
Administrative Assistant
Massachusetts Institute of Technology
Department of Chemistry
77 Massachusetts Ave, 6-333
Cambridge, MA 02139
p: 617.253.7239
e: cbrooks at mit.edu<mailto:cbrooks at mit.edu>

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