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【求助】我计算了分子的吸收和发射光谱
我计算了分子的吸收和发射光谱,发现吸收光谱的振子强度很大,超过2了,发射光谱的振子强度也大于1了,我想知道振子强度大于2这种情况是否合理。这是我的计算结果:【求助】我计算了分子的吸收和发射光谱
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【求助】我计算了分子的吸收和发射光谱
【求助】我计算了分子的吸收和发射光谱
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字体: 小 中 大 | 打印 发表于: 2016-3-19 10:54 作者: n111 来源: 分析测试百科网
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最新回复
dadaai (2016-3-19 10:54:29)
引用CCL上的一段讨论
why do you think that an oscillator strength f = 2.7 is unphysical? This is certainly a large value, but it is not necessarily unreasonable. With TD-PBE1PBE/6-31+G*, we obtained f = 2.2 for the first optically allowed electronic transition in the D2d conformation of diphenyldiacetylene, see Thulstrup et al., PCCP 13, 16168-16174 (2011).
According to Thomas-Reiche-Kuhn sum rule, the f-value for an electronic transition is not limited to magnitudes below or equal to unity, it may increase unity. As a matter of fact, it frequently does. For example, the experimental oscillator strength for the first transition in all-trans beta-carotene is equal to f = 2.7. This is the value obtained by integration over the absorption band in hexane with maximum at 22200 cm-1 and eps = 139400 (cuturl('http://omlc.ogi.edu/spectra/PhotochemCAD')), yielding f = 4.32E-9 * INT = 2.73. For the extremely strong band with maximum at 44800 cm-1 and eps = 1.1E6, integration yields f > 7.
青青草 (2016-3-19 10:54:49)
双子座 (2016-3-19 10:55:18)
Excitation energies and oscillator strengths:
PP熊 (2016-3-19 10:55:43)
根据Kasha定则,我们主要关注S1→S0的跃迁。那么第一激发态的波长位置就是荧光发射谱的谱峰位置吗?f=0.0000 怎么理解啊,这是跃迁禁戒的。而激发态S2和S3具有很大的振子强度,怎么理解呢?另外看到有采用计算频率,即:使用Franck-Condon原理根据振幅来拟合谱峰强度。具体怎么操作呢,
qinqinai (2016-3-19 10:56:04)
冰激凌 (2016-3-19 10:56:28)
xiaoxiaojinglin (2016-3-19 10:56:54)
可以做个频率计算看下是否有虚频,再判断
PP熊 (2016-3-19 10:57:18)
cuturl('http://emuch.net/bbs/viewthread.php?tid=3515618&fpage=1')
cuturl('http://emuch.net/bbs/viewthread.php?tid=5546124&fpage=1&target=self&page=1')
兔子 (2016-3-19 10:57:48)
QQ爱 (2016-3-19 10:58:12)
【求助】我计算了分子的吸收和发射光谱