Modulation of Visible Room Temperature Phosphorescence by Weak Magnetic Fields

Area of Science:

• Molecular photophysics
• Spin chemistry

Background:

• Controlling excited states of molecules with magnetic fields is crucial for various applications.
• Room temperature phosphorescence in multichromophoric systems is of significant interest.

Purpose of the Study:

• To investigate the modulation of visible room temperature phosphorescence in Pt porphyrin-Rosamine B dyads using weak magnetic fields.
• To elucidate the mechanism of magnetic field effects (MFE) on spin dynamics in photogenerated radical pairs (RPs).

Main Methods:

• Utilizing multichromophoric donor-acceptor systems (Pt porphyrin-Rosamine B dyads).
• Employing magnetic fields (<1 T) to probe spin dynamics.
• Analyzing ultrafast quantitative formation of local triplet states and subsequent radical pair intermediates.

Main Results:

• Demonstrated that weak magnetic fields can modulate visible room temperature phosphorescence.
• Observed MFE upon direct excitation of the Pt porphyrin component.
• Proposed a model involving reversible electron transfer between triplet states and long-lived RPs.

Conclusions:

• External magnetic fields can influence phosphorescence by modulating spin dynamics in radical pairs.
• The findings open new avenues for magnetic control of molecular excited states and photophysical processes.