Photochemistry sample sticks for inelastic neutron scattering.

Area of Science:

• Materials Science
• Spectroscopy
• Photochemistry

Background:

• Atomic and molecular motions are fundamental to material properties, studied via vibrations or phonons.
• Optical spectroscopy (Raman, IR, INS) probes material properties, while pump-probe methods study excited states.
• Inelastic neutron scattering (INS) has been limited in studying photoactive materials due to experimental challenges.

Purpose of the Study:

• To overcome experimental limitations hindering in situ INS studies of photoactive materials.
• To enable the investigation of photochemical reactions and excited states using INS.
• To broaden the application of INS to photoactive systems.

Main Methods:

• Design and implementation of two novel photochemistry sample sticks.
• Utilizing the VISION instrument at Oak Ridge National Laboratory for INS measurements.
• Demonstration with in situ photodimerization of anthracene and photopolymerization of a photoresin.

Main Results:

• Successful development of experimental apparatus for in situ photochemical studies using INS.
• Demonstrated capability to study real-time photodimerization and photopolymerization processes.
• Overcame previous limitations of neutron and photon penetration depth mismatches and optical access.

Conclusions:

• The developed sample sticks significantly expand the scope of INS research.
• Enables in situ studies of photoactive materials, excited states, and photoinitiated reactions.
• Opens new avenues for understanding light-matter interactions in materials.