Ultrafast electron diffraction from transiently aligned asymmetric top molecules: Rotational dynamics and structure...

Area of Science:

• * Molecular dynamics and structural analysis.
• * Advanced spectroscopy and diffraction techniques.

Background:

• * Ultrafast electron diffraction (UED) has been successful in determining the structures of linear and symmetric top molecules.
• * However, retrieving structural information from aligned asymmetric top molecules using UED remains a challenge.
• * Previous UED studies on asymmetric tops have recorded molecular alignment but failed to extract structural data.

Purpose of the Study:

• * To present a proof-of-principle for recovering the full structure of asymmetric top molecules using UED.
• * To demonstrate the extraction of two-dimensional structural information from simple transformations of experimental diffraction patterns.
• * To show that UED can distinguish between atomic pairs based on their orientation relative to the alignment axis.

Main Methods:

• * Alignment of 4-fluorobenzotrifluoride molecules using a linearly polarized laser.
• * Analysis of experimental ultrafast electron diffraction patterns.
• * Numerical simulations involving cooling molecules to a rotational temperature of 1 K.

Main Results:

• * Demonstrated the ability to distinguish between atomic pairs with equal distances that are parallel versus perpendicular to the molecular alignment axis.
• * Showed that specific transformations of diffraction patterns yield 2D structural information.
• * Numerical simulations indicate enhanced structural resolution at low temperatures.

Conclusions:

• * The presented method enables the extraction of 2D structural information from UED of aligned asymmetric top molecules.
• * This approach serves as a crucial proof-of-principle for future full molecular structure determination using UED.
• * Cooling molecules to low temperatures can significantly improve the resolution of structural parameters from diffraction data.