[18a-C309-1~10] 8.2 Plasma deposition of thin film, plasma etching and surface treatment

[18a-C309-10] Electronic properties and dissociation channels of CH₃F

〇Toshio Hayashi¹, Kenji Ishikawa¹, Makoto Sekine¹, Masaru Hori¹ (1.Nagoya university)

Keywords:Semiconductor, Etching

Electronic properties and dissociation channels of CH₃F were not fully discussed. On the other hand, electronic properties of CH3I were comprehensively discussed by Herzberg and suggested that an excited state shifts from the C_3v to a Cs structure by strong Jahn-Teller effect. Similarly, it can be thought that the excitation of CH₃F is also affected by strong Jahn-Teller effect. The VUV spectrum of CH₃F was reported by Locht et al., in which C band (11.3 eV) is a matter of argument. This band cannot be represented at the ground state minimum structure (C_3v) by using EOMCCSD/aug-cc-pVTZ+4s+4p.
We calculated the potential surfaces for excited states along F-C-H angle, C-F bond length, and C-H bond length to clarify the strong Jahn-Teller effect and dissociation channels. We confirmed the Jahn-Teller effect and the dissociation channels of CH₃F to CH₃⁺ + F^- along the C-F bond length and to CH₂ + HF along F-C-H bong angle.