Yoshikawa Takashi, Sumiyoshi Yoshihiro, Endo Yasuki
Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
J Chem Phys. 2009 Apr 28;130(16):164303. doi: 10.1063/1.3120444.
Pure rotational transitions of a new carbon-chain radical CCCF in a supersonic jet have been observed for the first time using a Fourier-transform microwave spectrometer with a pulsed-discharge nozzle. The radical was produced by a pulsed electric discharge in a C(2)H(2) and CF(4) mixture diluted to 0.1% and 0.1% with Ne, respectively. Rotational transitions with spin and hyperfine splittings have been observed in the region from 9.1 GHz for N(K(a)K(c)) = 1(01)-0(00) to 27.3 GHz for N(K(a)K(c)) = 3(03)-2(02). The rotational constant, the spin-rotation interaction constant, and the hyperfine coupling constants due to the F nucleus have been precisely determined from the least-squares analysis, yielding B = 4555.8043(44), gamma(eff) = -7.105(16), b(F,eff) = 368(19), and c(eff) = -284.832(61) MHz. The determined molecular constants were compared with those obtained from high-level ab initio calculations and concluded that the CCCF radical has a bent ground state X(2)A(').
首次使用带有脉冲放电喷嘴的傅里叶变换微波光谱仪，在超声速射流中观测到了一种新的碳链自由基CCCF的纯转动跃迁。该自由基是通过在分别用氖稀释至0.1%和0.1%的C₂H₂和CF₄混合物中进行脉冲放电产生的。在从9.1 GHz（对于N(KₐKc) = 1(01)-0(00)）到27.3 GHz（对于N(KₐKc) = 3(03)-2(02)）的区域内观测到了具有自旋和超精细分裂的转动跃迁。通过最小二乘法分析精确确定了转动常数、自旋-转动相互作用常数以及由于F原子核产生的超精细耦合常数，得到B = 4555.8043(44)、γ(eff) = -7.105(16)、b(F,eff) = 368(19)和c(eff) = -284.832(61) MHz。将确定的分子常数与从高水平从头算计算中获得的常数进行了比较，得出CCCF自由基具有弯曲基态X²A′的结论。
