
Dispersed fluorescence spectroscopy of the SiCN ˜A2Δ – ˜X2Π system : Observation of some vibrational levels with chaotic characteristicsDispersed fluorescence spectroscopy of the SiCN ˜A2Δ – ˜X2Π system : Observation of some vibrational levels with chaotic characteristicsAA00694991 
"/FUKUSHIMA,Masaru/"FUKUSHIMA,Masaru ,
"/ISHIWATA,Takashi/"ISHIWATA,Takashi
145
(
21
)
, pp.2143041

21430419 , 20161207 , American Institute of Physics
ISSN:00219606
NII書誌ID(NCID):AA00694991
内容記述
The laser induced fluorescence (LIF) spectrum of the ˜A 2Δ – ˜X 2Π transition was obtained for SiCN generated by laser ablation under supersonic free jet expansion. The vibrational structures of the dispersed fluorescence (DF) spectra from single vibronic levels (SVL’s) were analyzed with consideration of the RennerTeller (RT) interaction. Analysis of the pure bending (ν2) structure by a perturbation approach including RT, anharmonicity, spinorbit (SO), and HerzbergTeller (HT) interactions indicated considerably different spin splitting for the μ and κ levels of the ˜X 2Π state of SiCN, in contrast to identical spin splitting for general species derived from the perturbation approach, where μ and κ specify the lower and upper levels, respectively, separated by RT. Further analysis of the vibrational structure including RT, anharmonicity, SO, HT, Fermi, and Sears interactions was carried out via a direct diagonalization procedure, where Sears resonance is a secondorder interaction combined from SO and HT interactions with ΔK = ±1, ΔΣ = ∓1, and ΔP = 0, and where P is a quantum number, P = K + Σ. The later numerical analysis reproduced the observed structure, not only the pure ν2 structure but also the combination structure of the ν2 and the Si–CN stretching (ν3) modes. As an example, the analysis demonstrates Sears resonance between vibronic levels, (0110) κ Σ(+) and (0200) μ Π12, with ΔK = ±1 and ΔP = 0. On the basis of coefficients of their eigen vectors derived from the numerical analysis, it is interpreted as an almost onetoone mixing between the two levels. The mixing coefficients of the two vibronic levels agree with those obtained from computational studies. The numerical analysis also indicates that some of the vibronic levels show chaotic characteristics in view of the twodimensional harmonic oscillator (2DHO) basis which is used as the basis function in the present numerical analysis; i.e., the eigen vectors for some of the observed levels have several components of the basis, and we have not been able to give precise vibronic assignments for the levels, but just vibronically labeled, referring the largest component in their vectors. (To emphasize this situation, we do not use the word “assignment,” but prefer to use “label” as the meaning of just “label,” but not “assign,” throughout this paper.) The latter shows that the vibronic labels of the levels are meaningless, and the P quantum number and the order of their eigen states in the P matrix block derived in the numerical analysis only characterize the vibronic levels. Comparing the constants obtained for all of the interactions with those of species showing Sears resonance and studied previously, it is found that none of them are strong, but are moderate. It is thus concluded that the chaotic appearance is not derived by any strong interaction, but is induced by complex and accidental proximities of the vibronic levels caused by the moderate interactions. Published by AIP Publishing.
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