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Formation of intramolecular poly(4-hydroxystyrene) dimer radical cation
Kazumasa Okamoto1, Takahiro Kozawa, Kenichiro Natsuda
1The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan. kazu62@sanken.osaka-u.ac.jp
The Journal of Physical Chemistry. B
|July 18, 2008
Summary
Researchers studied poly(4-hydroxystyrene) (PHS) radical cations using pulse radiolysis. They observed charge resonance bands, indicating pi-pi interactions, and found dimer formation reduces deprotonation, crucial for lithography applications.
Area of Science:
- Polymer Science
- Photochemistry
- Materials Science
Background:
- Poly(4-hydroxystyrene) (PHS) is a key polymer in lithography.
- Understanding PHS radical cation dynamics is vital for advanced lithography techniques like extreme-ultraviolet and electron beam lithography.
Purpose of the Study:
- To investigate the dynamics of poly(4-hydroxystyrene) radical cations generated by electron beam exposure.
- To elucidate the role of charge resonance stabilization in PHS radical cation behavior.
Main Methods:
- Pulse radiolysis was employed to generate and study transient species.
- Transient absorption spectroscopy in the near-infrared region was used to observe PHS radical cations in p-dioxane solutions.
Main Results:
- Distinct charge resonance (CR) bands were observed, signifying pi-pi interactions within intramolecular PHS dimer radical cations.
- Unlike p-cresol, PHS exhibited unique CR band characteristics.
- Charge resonance stabilization was found to significantly reduce the deprotonation of PHS dimer radical cations.
Conclusions:
- The study reveals the formation and characteristics of PHS dimer radical cations.
- Charge resonance stabilization plays a critical role in the stability of PHS radical cations, impacting their behavior in lithographic processes.
- These findings contribute to the development of advanced lithography materials.
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