Laser Ablation of Trp-Gly
| Autor: | Jeffrey W. Elam, Donald H. Levy |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Laser ablation
Chemistry medicine.medical_treatment Analytical chemistry chemistry.chemical_element Ablation Laser Molecular physics Boltzmann distribution Surfaces Coatings and Films law.invention Flow velocity law Materials Chemistry medicine Mass spectrum Physical and Theoretical Chemistry Molecular beam Helium |
| Zdroj: | The Journal of Physical Chemistry B. 102:8113-8120 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/jp982545+ |
| Popis: | We studied laser ablation of Trp-Gly under the same experimental conditions used previously to successfully seed this fragile, nonvolatile dipeptide into a molecular beam. A film of Trp-Gly was prepared on a brass plate and laser ablated with 11 ns, 8 J/cm2, 5320 A laser pulses. We found substantial fragmentation upon ablation and believe that immediate helium entrainment is necessary to prevent decomposition. The velocity distribution is broader than a Boltzmann distribution, exhibits no flow velocity, and has a translational temperature Tt = 4200 K. The angular distribution is highly forward-peaked and bimodal with a major component proportional to cos41 θ. When laser ablated under identical conditions, tryptamine has a similar angle velocity distribution and also shows significant fragmentation. Analysis of its mass spectrum yields an internal temperature Ti = 660 K. Existing collisional models cannot explain the measured angle velocity distributions. They may result from the pulsed nature of the expan... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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