Liu H, Lim EC, Niño A, Muñoz-Caro C, Judge RH, Moule DC
Knight Chemical Laboratory, University of Akron, Akron, Ohio, 44325-3601
J Mol Spectrosc. 1998 Jul;190(1):78-90. doi: 10.1006/jmsp.1998.7560.
The band assignments and analyses of the jet-cooled high-resolution laser-induced fluorescence excitation spectrum of acetaldehyde that results from the S1(n, pi*) electronic state have been extended to +600 cm-1 from the 0(0)0 system origin. The new assignments start at Band #7 and finish at Band #21. Bands #8 and #9, originally assigned to 14(2)0, have now been assigned to 15(3)0. The assignments of the lower energy bands remain unaltered. The origins of the bands that involve the torsional modes nu15 (v = 1 to 4) in combination with the wagging mode nu14 (v = 1 and 2) and the nu10 (v = 1) were determined by analyses with a rigid rotational Hamiltonian. These origins were fitted to a set of levels that were derived from a torsion-wagging-bending Hamiltonian that employed flexible large amplitude coordinates. The resulting potential surface was found to have barriers to torsion and inversion of 712.5 and 638.6 cm-1, respectively, with minima in the potential hypersurface at theta = 59.9 degrees and alpha = 33.5 degrees for the torsion and wagging coordinates. Copyright 1998 Academic Press.
对由S1(n, π*)电子态产生的乙醛喷射冷却高分辨率激光诱导荧光激发光谱的谱带归属及分析已从0(0)0体系原点扩展至+600 cm-1。新的归属从第7谱带开始，至第21谱带结束。最初归属为14(2)0的第8和第9谱带，现重新归属为15(3)0。低能谱带的归属保持不变。通过使用刚性转动哈密顿量进行分析，确定了涉及扭转模式ν15（v = 1至4）与摇摆模式ν14（v = 1和2）以及ν10（v = 1）组合的谱带的原点。这些原点被拟合到一组由采用灵活大振幅坐标的扭转-摇摆-弯曲哈密顿量导出的能级上。结果发现，所得势能面的扭转和反转势垒分别为712.5和638.6 cm-1，对于扭转和摇摆坐标，势能超曲面的最小值分别位于θ = 59.9度和α = 33.5度处。版权所有1998年，学术出版社。
