| Autor: |
I.G. Ross, J.M. Hollas, K.K. Innes |
| Rok vydání: |
1966 |
| Předmět: |
|
| Zdroj: |
Journal of Molecular Spectroscopy. 20:312-320 |
| ISSN: |
0022-2852 |
| DOI: |
10.1016/0022-2852(66)90002-6 |
| Popis: |
In the visible spectrum of p-benzoquinone-h4 and -d4, two unusual types of intensity distribution along sequence bands have been previously recorded experimentally. Both types have in common an intensity maximum which is not a the first band of the sequence. In one case the maximum is due to the fact that the sequence-forming vibration is involved in Herzberg-Teller intensity stealing and that the parent band of the sequence is a 1 ← 0 or 0 ← 1 band in the sequence-forming vibration. It is the unusually low frequency of the sequence-forming vibration (106 cm−1 in the ground state) which enables us to observe the maximum easily in this case. In the other case, the intensity maximum is caused by the overlapping of v + 2 ← v sequence bands with v ← v sequence bands. The unusually large increase in the sequence-forming vibration in the electronic excited state (it is 140 cm−1 in the excited state) is responsible for the appreciable intensity of the v + 2 ← v bands. A theoretical interpretation of these two cases is given here and it becomes apparent that the unusual sequence intensity distributions will indeed be uncommon: it is fortunate that conditions in the p-benzoquinone spectrum are such that two unusual cases have been observed both, we believe, for the first time. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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