Ultrafast photodissociation dynamics and energetics of the electronically excited H atom transfer state of the ammonia dimer and trimer
| Autor: | Ingolf V. Hertel, H.-H. Ritze, W. Radloff, V. Stert, P. Farmanara |
|---|---|
| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 116:1443-1456 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/1.1429952 |
| Popis: | The energetics and ultrafast dynamics in the H atom transfer configuration of ammonia dimer and trimer clusters have been studied. The clusters are first excited to the electronic A state with a 208 nm femtosecond laser pump pulse. This state is allowed to relax for about 1 ps during which the H-transfer state is formed which is then electronically excited by a time-delayed infrared control pulse at 832 nm and finally ionized with a third femtosecond probe pulse at 416 nm. We have also performed complementary theoretical studies elucidating the experimental findings. For the dimer in the excited NH4(3p)⋯NH2(X) state the time-dependent ion signals reveal an isotope-independent short lifetime of about τ6=(130±60) fs which can be explained by a curve crossing with the repulsive NH4(3s)⋯NH2(A) state, whereas the trimer signal persists on a time scale being more than one order of magnitude longer and exhibits a very large isotope effect. This is interpreted as being due to internal conversion from the excited... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|