研究目的
To characterize β-monofluoro (MFEO), β,β-difluoro (DFEO), and β,β,β-trifluoro ethoxy (TFEO) radicals by moderate-resolution LIF and DF spectroscopy and to analyze the tendencies in structural and spectroscopic properties as the function of the number of fluorine atom, which can help to understand the reactivity and, therefore, the atmospheric lifetime of these species.
研究成果
The study successfully characterized the B?←X? LIF and DF spectra of MFEO, DFEO, and TFEO radicals, confirming the significant impact of long-range field effects on their electronic transition energies and bond strengths. The computational simulations, despite some discrepancies, provided valuable insights into the structural and spectroscopic properties of these radicals, aiding in understanding their atmospheric reactivity and lifetime.
研究不足
The study is limited by the computational overestimation of B?-state CO-stretch frequencies for the G conformer of DFEO and the inability to reproduce the splitting in overtone and combination transitions involving the CO-stretch mode in TFEO due to interaction with ?CF3 internal rotation.
1：Experimental Design and Method Selection:
The study involved recording the B?←X? LIF and DF spectra of CHxF3?xCH2O (x=1,2,3) fluoroethoxy radicals under jet-cooled conditions. Franck-Condon factors were obtained from quantum chemical computations at the CAM-B3LYP/6-311++G(d,p) level of theory.
2：Sample Selection and Data Sources:
Fluoroethyl nitrite was prepared from fluoroethanol, difluoroethyl nitrite from difluoroethanol, and trifluoroethyl nitrite from trifluoroethanol.
3：List of Experimental Equipment and Materials:
A pulsed Nd:YAG laser for photolysis, a tunable dye laser for probing, a photomultiplier tube for fluorescence detection, and a monochromator for dispersed fluorescence spectroscopy.
4：Experimental Procedures and Operational Workflow:
The precursors were photolyzed to produce the desired fluorinated alkoxy radicals, which were then probed downstream. The LIF and DF spectra were recorded and analyzed.
5：Data Analysis Methods:
The spectra were simulated using calculated harmonic vibrational frequencies and FCFs, with scaling factors applied to match experimental values.
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