Heterogeneous relaxation patterns in supercooled liquids studied by solvation dynamics

Area of Science:

• Physical Chemistry
• Chemical Physics
• Materials Science

Background:

• Supercooled liquids exhibit complex dynamics near the glass transition.
• Understanding relaxation processes is crucial for predicting material properties.

Purpose of the Study:

• To investigate solvation dynamics in a dipolar supercooled liquid.
• To characterize relaxation behavior over a wide temperature range.

Main Methods:

• Measured time-dependent average emission energy.
• Analyzed inhomogeneous linewidth of the S0<--T1(0-0) transition.
• Studied dynamics in a temperature range spanning four orders of magnitude of relaxation time.

Main Results:

• Identified an intrinsic stretching exponent beta(intr)=1.00+/-0.08 for orientation correlation decay.
• Observed persistent fluctuations and lack of homogeneity in the long-time decay tail.
• Found no transition to purely exponential behavior even at times significantly exceeding average structural relaxation time.

Conclusions:

• Individual time constants in supercooled liquids remain correlated to initial values.
• The observed behavior implies memory effects persist beyond the average structural relaxation time.
• Dipolar supercooled liquids maintain non-exponential relaxation dynamics near the glass transition.