Studies on Molecular Structure and Dynamics by Doppler-free High-resolution Laser Spectroscopy

1.在6T磁场下测量反式乙二醛A^1A_u(v_7=1)←X^1A_g跃迁的无多普勒双光子荧光激发光谱。通过分析结果得出A^1^A_u态的塞曼分裂源于1^3Bu态通过自旋轨道相互作用的混合，磁矩沿顶轴。2.测量了气态苯-d_6中S_1^1B_<2u>←S_0^1A_<1g>跃迁低位振动带的高分辨率激发光谱和塞曼效应。在两个谱带中均未观察到源自与三重态相互作用的扰动。从塞曼光谱可以清楚地看出，旋转分辨能级并未与三重态混合。因此，得出结论：孤立苯的S_1态在低过剩能量水平下不太可能发生系间混合。3.测量了萘的S_1^1B_<1u>(v_<21>=1)←S_0^1A_g(v=0)跃迁的无多普勒双光子激发光谱和塞曼效应。发现旋转分辨能级不与塞曼光谱中的三重态混合。结果表明，在 S_1 态下激发至低振动电子水平的孤立萘通过系间混合不会发生非辐射衰变。 1884. 通过垂直于准直分子束的可调谐激光束穿过 S_1←S_0 跃迁的 0_0^0 和 0_0^0 22 cm^<-1> 带，观察到了二苯并-对-二恶英 (DD) 的亚多普勒高分辨率激发光谱。通过将光谱模拟为a型跃迁，观察到的光谱得到了很好的再现，并且S_1态被识别为^1B_<1u>态。 DD分子已被证明t 0_0^ 22 cm^<-1>带被指定为蝴蝶模式的a_g分量的过渡。

1.Doppler-free two-photon fluorescence excitation spectra of the A^1A_u(v_7=1)←X^1A_g transition of trans-glyoxal were measured under the magnetic field up to 6T. By analyzing the results, it is concluded that the Zeeman splitting of the A^1^A_u state is originating from the mixing of the 1^3Bu state by spin-orbit interaction and the magnetic moment is along the top axis.2.High resolution excitation spectra and the Zeeman effects for the low-lying vibrational band of the S_1^1B_<2u>←S_0^1A_<1g> transition in gaseous benzene-d_6 were measured. No perturbation originating from an interaction with a triplet state was observed in both bands. It became clear from the Zeeman spectra that rotationally resolved levels are not mixed with a triplet state. Accordingly, it was concluded that the intersystem mixing is not likely to occur at levels of low excess energy in the S_1 state of an isolated benzene.3.Doppler-free two-photon excitation spectrum and the Zeeman effect of the S_1^1B_<1u>(v_<21>=1)←S_0^1A_g(v=0) transition of naphthalene have been measured. Rotationally resolved levels were found not to be mixed with a triplet state from the Zeeman spectra. It is demonstrated that nonradiative decay of an isolated naphthalene excited to low rovibronic levels in the S_1 state does not occur through the intersystem mixing. 1884.Sub-Doppler high-resolution excitation spectra of dibenzo-p-dioxin (DD) have been observed for the 0_0^0 and 0_0^0+22 cm^<-1> bands of the S_1←S_0 transition by crossing a tunable laser beam perpendicular to a collimated molecular beam. The observed spectra were reproduced well by simulating the spectra as the a-type transition, and the S_1 state is identified to be a ^1B_<1u> state. The DD molecule has been shown t 0_0^+22 cm^<-1> band is assigned as a transition to the a_g component of butterfly mode.